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Downloaded by [Saudi Digital Library] at 09:02 10 October 2017 Downloaded by [Saudi Digital Library] at 09:02 10 October 2017 The Psychology of Health Its scope and accessibility make it an ideal introduction to health psychology for undergraduate students. The overall tone is sensible, friendly, and even at times humorous, combining detached, rational appraisal of psychological theory and research with reflective comments and questions…. Chapters have been updated with reference to recent research and the ‘Social Circumstances, Inequalities and Health’ chapter reflects the shift towards a greater awareness of the importance of gender, class and ethnicity. Lucy Yardley, University College London Health psychology is one of the fastest growing areas of the behavioural sciences. As such it occupies an increasingly important place in undergraduate and postgraduate courses. Students in other disciplines, such as nursing, social work, physiotherapy and occupational therapy, also need to learn about the role of psychology in understanding health and the treatment of illness. The first edition of The Psychology of Health was very well received and has become the standard recommended text for many courses. This completely revised and updated second edition contains new material in all chapters and has several additional chapters on such topics as cancer, nutrition and exercise, social drugs, and the impact of social inequalities upon health. This edition also contains annotated further reading, a glossary of key terms, boxes with ideas and questions for seminar topics, helpful revision points in chapter summaries and an extensive bibliography. The Psychology of Health will continue to be invaluable for students of health psychology and related behavioural and health sciences, including nursing, community care and health studies. Marian Pitts is Professor of Psychology at Staffordshire University. Previously she worked in Africa and has taught at the universities of East London, Tennessee and Zimbabwe. She is author of The Psychology of Preventive Health (1996). Keith Phillips is Professor of Psychology and Head of the School of Social and Behavioural Sciences at the University of Westminster. Both have published widely in the area of health psychology. Comments on the first edition: ‘I do not know of a better book in this field.’ Health Education Downloaded by [Saudi Digital Library] at 09:02 10 October 2017 ‘This is a very thorough and well-compiled text which should be on student reading lists for a good few years to come.’ Journal of Occupational and Organizational Psychology ‘Pitts and Phillips have given introductory-level health psychology teachers a valuable basic tool…. The editors and authors who came together to produce this fine volume have shared their extensive knowledge of health psychology and successfully conveyed their own excitement and enthusiasm about its goals and progress.’ Contemporary Psychology ‘An interesting and worthwhile contribution to important topics often neglected by other books.’ Stress News ‘A valuable overview text, pulling together a wide range of material which will aid students’ understanding of the health dimension of social work. Offers a broad range of foundation knowledge for first year post-graduate social work students.’ Sandra Butler, School of Social Studies, Nottingham University ‘Presents an issue-based approach to health psychology, therefore very useful for practitioners working in these specific areas.’ Frank Jacob, Faculty of Health and Community Care, University of Central England ‘A thorough and up-to-date text in a new and growing field of study.’ Yvonne Crome, School of Health and Applied Sciences, University College Suffolk ‘Ideal for nurses who are updating skills to degree level.’ Martin Johnson, Department of Psychology, Teeside University ‘Excellent overview with substantial reference list.’ John Wilson, Social and Professional Studies, Humberside University ‘Highly accessible to undergraduate students. The range of topics is highly relevant to a wide range of health care professionals.’ Lynette Rentoul, Nursing Studies Department, Kings College London ‘Brings together various strands of psychology into a very useful and readable text.’ Peter Wybrow, Social Sciences Faculty, Southton H.E. Institute Downloaded by [Saudi Digital Library] at 09:02 10 October 2017 of Health n An introduction Second edition Edited by Marian Pitts and Keith Phillips ROUTLEDGE The Psychology Downloaded by [Saudi Digital Library] at 09:02 10 October 2017 First edition published 1991 by Routledge Second edition published 1998 by Routledge 11 New Fetter Lane, London EC4P 4EE Simultaneously published in the USA and Canada by Routledge 29 West 35th Street, New York, NY 10001 Routledge is an imprint of the Taylor #038; Francis Group This edition published in the Taylor #038; Francis e-Library, 2003. © 1991, 1998 Selection and editorial matter, Marian Pitts and Keith Phillips; individual chapters © the contributors All rights reserved. No part of this book may be reprinted or reproduced or utilized in any form or by any electronic, mechanical, or other means, now known or hereafter invented, including photocopying and recording, or in any information storage or retrieval system, without permission in writing from the publishers. British Library Cataloguing in Publication Data A catalogue record for this book is available from the British Library. Library of Congress Cataloguing in Publication Data The psychology of health: an introduction/edited by Marian Pitts and Keith Phillips.—2nd ed. p. cm. Includes bibliographical references and indexes. 1. Clinical health psychology. 2. Medicine and psychology. I. Pitts, Marian, 1948–. II. Phillips, Keith, 1951–. R726.7.P794 1998 616’.001’9–dc21 97–40283 ISBN 0-203-44174-5 Master e-book ISBN ISBN 0-203-74998-7 (Adobe eReader Format) ISBN 0-415-15023-X (hbk) ISBN 0-415-15024-8 (pbk) Downloaded by [Saudi Digital Library] at 09:02 10 October 2017 To Gina, David and Sheila and Rosa and Bernard Downloaded by [Saudi Digital Library] at 09:02 10 October 2017 Downloaded by [Saudi Digital Library] at 09:02 10 October 2017 List of figures List of tables List of contributors Preface Acknowledgements List of abbreviations ix xi xii xiii xv xvii Part one INTRODUCTION 1 1 An introduction to health psychology 3 2 Psychophysiology, health and illness 25 3 Stress and coping 47 Contents Contents Part two PATIENT BEHAVIOUR AND THE MANAGEMENT OF ILLNESS 4 The medical consultation 69 71 vii CONTENTS 5 The experience of treatment 93 6 Pain: psychological aspects 109 Part three Downloaded by [Saudi Digital Library] at 09:02 10 October 2017 HEALTH ISSUES 129 7 Social drugs: effects upon health 131 8 The primary prevention of AIDS 149 9 Decision making for contraception and abortion 169 10 Essential hypertension 187 11 Coronary heart disease 205 12 Diabetes 225 13 Nutrition, exercise and health 243 14 Cancer 263 Part four WIDER SOCIAL ISSUES 15 16 Child health, illness and family influences 287 Social circumstances, inequalities and health 313 Glossary Bibliography Author index Subject index viii 285 329 337 391 403 Downloaded by [Saudi Digital Library] at 09:02 10 October 2017 Figures 1.1 1.2 1.3 1.4 2.1 2.2 2.3 2.4 3.1 3.2 3.3 4.1 4.2 4.3 7.1 7.2 9.1 10.1 11.1 Health belief model Leventhal’s self-regulatory model of illness behaviour Theory of planned behaviour Schwarzer’s health action process approach The organisation of the nervous system Generalised features of a psychophysiological recording and measurement system Biofeedback—the voluntary control paradigm The elements of biofeedback training Cognitive control model of stress Selye’s General Adaptation Syndrome Physiological stress systems and their interactions Antecedents to the consultation process Stages in making a diagnosis Ley’s cognitive model Self-rated feelings of stress, arousal and pleasure (UEL brief mood scales) in non-smokers, non-deprived smokers and overnight deprived smokers, before and after a rest/cigarette break Smoking abstinence rates under transdermal nicotine and transdermal placebo The family planning ‘factors wheel’ Risk of myocardial infarction occurring in next six years per 1000 men at different levels of systolic blood pressure Relative risk of coronary heart disease among civil servants, controlling for (a) age, and (b) age, smoking, blood pressure, plasma cholesterol and obesity 10 12 13 14 28 32 37 38 51 59 60 74 80 89 134 138 172 189 208 ix FIGURES 14.1 14.2 14.3 15.1 15.2 15.3 16.1 16.2 Downloaded by [Saudi Digital Library] at 09:02 10 October 2017 16.3 x Most common cancers in men in the UK, 1998 Most common cancers in women in the UK, 1998 Five-year survival percentages for men and women with cancers Bronfenbrenner’s ecological model Styles of parenting The family adjustment and adaptation response (FAAR) model Infant death rates by social class in England and Wales, 1979–1993 Mortality rates from coronary heart disease by regions in England for people aged 65–74 years (1990–1992) Prevalence of cigarette smoking by sex and socioeconomic group, Great Britian (1992) 265 266 267 289 291 293 316 321 328 Downloaded by [Saudi Digital Library] at 09:02 10 October 2017 Tables 2.1 5.1 5.2 6.1 7.1 8.1 10.1 12.1 13.1 13.2 13.3 15.1 15.2 Antagonistic actions of the divisions of ANS Assessing recovery Psychological interventions before surgery Exles of exaggerated pain perception as suggested by the fear-avoidance model of pain Medical and psychological effects of tobacco constituents: nicotine, tar and carbon monoxide Proportions who report sexual lifestyle change because of AIDS (by age group) Comparison of blood pressure reductions following stress management versus control procedures in clinic and non-clinic studies Educational messages about insulin and its administration Calculating body mass index (BMI) Diagnostic criteria for anorexia nervosa Diagnostic criteria for bulimia nervosa Infant mortality by social class, 1986–1990 in England and Wales Injury death rates per 100,000 children by social class and external cause, 1979–1983 and 1989–1992 29 101 102 116 136 155 198 228 251 254 254 294 298 xi Downloaded by [Saudi Digital Library] at 09:02 10 October 2017 Contributors Jacqueline Barnes Senior Lecturer and Honorary Senior Psychologist, Leopold Muller University Department of Child and Family Mental Health, Royal Free Hospital School of Medicine and the Tavistock Clinic, Hstead, London. Mar y Boyle Professor of Psychology and Course Director for Clinical Psychology, Department of Psychology, University of East London. Philip Evans Professor of Psychology and Director of the Psychophysiology and Stress Research Group, Department of Psychology, School of Social and Behavioural Sciences, University of Westminster. Paula Hixenbaugh Depar tment of Psychology and Member of Health Psychology Research Group, School of Social and Behavioural Sciences, University of Westminster. Andrew Parrott Reader in Psychology, Department of Psychology, University of East London. Keith Phillips Professor of Psychology, Member of the Health Psychology Research Group, and Head of School of Social and Behavioural Sciences, University of Westminster. Marian Pitts Professor of Psychology, Division of Psychology, Staffordshire University. Hartwin Sadowski Lecturer and Honorary Senior Registrar, Leopold Muller University Department of Child and Family Mental Health, Royal Free Hospital School of Medicine and the Tavistock Clinic. Tara Symonds Lecturer in Health Psychology, Division of Psychology, Staffordshire University. Laura Warren Research Associate, Department of Psychology, School of Social and Behavioural Sciences, University of Westminster. David White Professor of Psychology, Division of Psychology, Staffordshire University. xii Downloaded by [Saudi Digital Library] at 09:02 10 October 2017 Preface The initial stimulus for this book came from the many students whose obvious enthusiasm for health psychology caused us to undertake writing the first edition. At that time we (the editors) could not find a book that was suitable to recommend to our students as a standard text. Those texts that did exist were written by American academics who had different experiences and were writing from knowledge of a different health system. We were encouraged by colleagues and students to compile a book that would be relevant to UK students and teachers. The contribution of those students was great and we hope that they will gain some satisfaction from realising their part in the appearance of the first edition. This, the second edition, builds upon the first, which we are gratified to say was well received and has become the standard recommended text for many courses in the UK. It has been updated by the addition of new material in all the chapters and by the addition of entirely new chapters, including those on cancer, nutrition and exercise, and the impact of social inequalities upon health. Since the first edition was published in 1991, learned societies for the study of health psychology have been established and several new journals have begun to publish research in this new and exciting area of psychology. Courses dedicated to the study of health psychology have been developed in our universities and colleges, and many areas of the health and nursing sciences include health psychology as part of their curriculum. The book is divided into four parts. Part One provides an introduction to health psychology, including its definition and an overview of its scope and ambitions. There is a discussion of the principles and techniques of psychophysiology and consideration of an area that has been central to the understanding of individuals’ health, namely stress and coping. This section concludes with an update on the developing area of psychoneuroimmunology. xiii P R E FA C E Downloaded by [Saudi Digital Library] at 09:02 10 October 2017 Part Two considers studies that are relevant to the experiences of illness, hospitalisation and the management of disease. Part Three contains topics of significance for health psychologists. These have been chosen to reflect the diversity of health issues studied by health psychologists, including acute and chronic illness, primary prevention of illness, and health promotion. Many of these have been highlighted by the UK government’s Health of the Nation programme. Part Four broadens the book’s perspective, moving beyond an individualistic approach to consider the importance of family and wider social contexts for health. In this edition you will find a glossary, boxes with ideas and questions about the contents of each chapter, helpful revision points in the key summaries, suggestions for further reading, indexes, and an extensive bibliography. The book is aimed at advanced undergraduates in psychology and related disciplines, especially the behavioural and health sciences, including nursing, community care, and health studies. It does not assume that you will have extensive prior knowledge of psychology. However, we hope too that some of the ideas contained in the chapters will provoke thought among those of you who are embarking upon postgraduate study in health psychology. We hope that you will find the book readable, interesting and challenging, but most of all that it will excite you to read more about health psychology and perhaps become a health psychologist yourself. Whatever your reasons for choosing to read this book we hope that you will find within it something of value to you. Marian Pitts Keith Phillips July 1997 xiv Downloaded by [Saudi Digital Library] at 09:02 10 October 2017 Acknowledgements The editors would like to thank first the contributors, who adhered to their deadlines and helped us in many ways throughout the preparation of this book. We would like also to acknowledge the support given to us by our colleagues and friends in our respective departments in Staffordshire and Westminster. We have received advice from many friends; all errors remain, unfortunately, our own. We also thank those students whose enthusiasm for health psychology caused us to compile the first edition and the many groups of students since whose feedback has encouraged us to undertake this second edition. Again we also owe great thanks to our partners and families for their support during the period of production of the book; their tolerance, good humour and general assistance throughout the project has done much to ensure its final delivery. We owe particular thanks to Carol Austin and Qazi Rahman, who have been very helpful in tracking down elusive references and compiling the index, and to Sheelagh Rowbottom, Social Sciences Librarian at Staffordshire, who was always eager to provide help. All photographs were supplied by Photofusion: Part one (page 2) Marylebone Station, copyright Steve Eason Dance and exercise class, copyright Bob Watkins Part two (page 70) GP and patients, copyright Reen Pilkington Ambulance, copyright Sam Tanner Part three (page 130) Beer belly, copyright David Montford Active elderly man, copyright Tim Dub xv ACKNOWLEDGEMENTS Part four (page 286) Bengali children playing on Whitechapel Estate, copyright Crispin Hughes School nurse discussing anti-smoking caign project with pupils, Surrey Docks, copyright Brenda Prince Downloaded by [Saudi Digital Library] at 09:02 10 October 2017 The following organizations have kindly given permission to use figures: Figure 1.1 Lippincott-Raven Publishers; Figure 1.2 Elsevier Scientific Publishers; Figure 1.4 Open University Press; Figure 4.1 Oxford University Press; Figures 7.2 and 9.1 Carfax Publishing Limited, PO Box 25, Abingdon, Oxfordshire OX14 3UE; Figure 10.1 (adapted from Strasser, 1992), Macmillan Press Limited; Figures 14.1, 14.2 and 14.3 Cancer Research Caign and its Scientific Yearbook; Figure 15.2 reprinted with permission of the Helen Dwight Reid Educational Foundation. Published by Heldref Publications, 1319 Eighteenth Street, N.W., Washington, D.C. 20036–1802. Copyright © 1967; Figure 15.3 W.B.Saunders Company. The following organizations have kindly given permission to use tables: Table 8.1 Blackwell Scientific Publications; Tables 15.1 and 15.2 the BMJ Publishing Group. Ever y effor t has been made to trace copyright holders and obtain permission to reproduce figures and tables. Any omissions brought to our attention will be remedied in future editions. Finally, we would like to thank Vivien Ward of Routledge for suggesting that we produce a second edition and Jon Reed for his patience, encouragement and assistance throughout the production process. xvi Downloaded by [Saudi Digital Library] at 09:02 10 October 2017 Abbreviations ACTH AIDS ANS APA ARC BAC BDA BDI BPL BPS BRS BSE CHD CNS CO CRF DCCT DFBC DQOL DUKE ECG EEG EMG EORTC EPIC ESRC Adrenocorticotrophic hormone Acquired Immune Deficiency Syndrome Autonomic nervous system American Psychological Association AIDS-related complex Blood alcohol concentration British Diabetic Association Beck Depression Inventory Blood pressure level British Psychological Society Bortner rating scale Breast self examination Coronary heart disease Central nervous system Carbon monoxide Corticotropin releasing factor Diabetes Control and Complications Trial Diabetes family behaviour checklist Diabetes quality of life (scale) Duke health profile Electrocardiogram Electroencephalogram Electromyogram European Organisation for Research on Treatment of Cancer European Prospective Investigation of Cancer Economic and Social Research Council xvii A B B R E V I AT I O N S Downloaded by [Saudi Digital Library] at 09:02 10 October 2017 5-HT FAAR FAM FTAS GHP GP HAPA HBM HDL HIV HPA IBQ ICU IDDM ivdu JAS JHPS MDMA MI mmHg MMPI MPI MPQ MRFIT MSPQ NIDDM NK PCA PNI PNS PVC QOL SAM SI sIgA SIP SLM THC TPB TSE WCGS WEHS WHO xviii Serotonin (5-hydroxytryptamine) Family adjustment and adaptation response Fear avoidance model (of pain) Framingham Type A Scale General health perceptions (scale) General practitioner Health action process approach Health belief model High density lipoprotein Human Immunodeficiency Virus Hypothalamic pituitary-adrenocortical (axis) Illness behaviour questionnaire Intensive care unit Insulin-dependent diabetes mellitus intravenous drug user Jenkins Activity Survey Johns Hopkins Precursors Study Ecstasy Myocardial infarction Millimetres of mercury Minnesota multiphasic personality inventory Multidimensional pain inventory McGill pain questionnaire Multiple risk factor intervention trial Modified somatic perception questionnaire Non-insulin-dependent diabetes mellitus Natural killer (cell) Patient controlled analgesia Psychoneuroimmunology Peripheral nervous system Premature ventricular contraction Quality of life Sympathetic adrenal medullary (system) Structured interview Secretory immunoglobulin A Sickness impact profile Social learning model Tetrahydrocannabinol Theory of planned behaviour Testicular self examination Western Collaborative Group Study Western Electric Health Survey World Health Organization Downloaded by [Saudi Digital Library] at 09:02 10 October 2017 Introduction P ART ONE introduces you to the basic elements underpinning the psychology and experience of health. We need explanations of the ways in which psychological variables interact with biological predispositions of disease, and environmental and social factors such as economic status. These explanations give rise to theories of health behaviour. Chapter 1 reviews the evidence which implicates health behaviours and other psychological variables as major determinants of health; it shows how the causes of ill health and death have changed in the western world over the last century from infectious diseases to those linked to behaviours, including cancers, and circulatory diseases. The approach adopted throughout the book is to view health as a function of biological, psychological and social elements—known as the biopsychosocial approach. Several models are reviewed in Chapter 1, and will be used as the basis for understanding a range of health issues that are covered by chapters in Part Three. Chapter 2 reviews the biological underpinnings of health and health behaviours. It is necessary to understand how the nervous system, the endocrine and immunological systems together regulate physiological reactions and behaviour. Biofeedback is introduced as an exle of the importance of physiological regulation in modifying reactions, and hence to reducing risks associated with psychophysiological disorders. Chapter 3 considers the constructs of stress and coping. Stress has come to be regarded (rightly or wrongly) as one of the major problems of our busy lives. In this chapter we consider carefully the nature of the construct and look at how it has been measured. Philip Evans examines closely the physiological basis of the concept. He then considers the other construct: coping. Coping also needs to be ‘unpacked’ to understand how it is that we can cope with stress and why some people appear to manage to do so better than others. Finally, the exciting new field of psychoneuroimmunology is reviewed to show how psychology and physiology interact in determining health. Part one Part one 1 Downloaded by [Saudi Digital Library] at 09:02 10 October 2017 Downloaded by [Saudi Digital Library] at 09:02 10 October 2017 An introduction to health psychology Marian Pitts Introduction What is health and what is health psychology? Historical background Health behaviours Models of health behaviour The health belief model (HBM) Protection motivation theory Leventhal’s self-regulatory model The theory of planned behaviour (TPB) Schwarzer’s health action process approach (HAPA) The transtheoretical model Comparing the models Individual differences Health locus of control Self-efficacy Optimism Doing health psychology research Ethics in health psychology research Key point summary Further reading 4 4 5 6 9 9 11 11 12 14 15 16 16 16 17 18 19 20 22 23 Chapter 1 Chapter 1 3 INTRODUCTION Introduction Downloaded by [Saudi Digital Library] at 09:02 10 October 2017 This chapter will introduce the area of health psychology. It will outline briefly the historical background to the field, consider the development of our understanding of health behaviours and introduce the major models which have been developed to aid our understanding of people’s health-related behaviours. We will look at individual differences and how they impact on health behaviours. Finally, we will consider the methodologies used in health research and the particular ethical problems which accompany research in these areas. What is health and what is health psychology? How are you feeling today? As you read these words are your eyes sore? Does your back ache? How’s the head? Do you find your concentration wandering (already?!). It is extremely unlikely that anyone reading this book is entirely and absolutely healthy and free of symptoms. It would be difficult to know what that would mean; we all are ‘imperfect machines’. The study of health psychology is concerned with the ways in which we, as individuals, behave and interact with others in sickness and in health. Any activity of psychology which relates to aspects of health, illness, the health care system, or health policy may be considered to be within the field of health psychology. Health psychology deals with such questions as: What are the physiological bases of emotion and how do they relate to health and illness? Can certain behaviours predispose to particular illnesses? What is stress? Can educational interventions prevent illness? And many others. The beginnings of the formal interest of psychologists in these areas can be dated to the convening of a conference in the USA in 1978 and to the creation of a section devoted to health psychology in the American Psychological Association in 1979. The British Psychological Society (BPS) set up a Health Psychology Section only in 1986. This year (1997) the section should become a formally recognised division of the BPS and the profession of health psychologist may be established in the UK. Some time ago the World Health Organization put forward a definition of health which has been widely quoted. Health is ‘a state of complete physical, mental and social well-being and not merely the absence of disease or infirmity’ (WHO, 1946). Recently this definition has come under scrutiny and some criticism as representing an unrealistic goal, nevertheless it does emphasise the holistic nature of health involving body and spirit, physical and mental states. Matarazzo in 1980 offered a definition of health psychology which has become widely accepted: Health psychology is the aggregate of the specific educational, scientific and professional contributions of the discipline of psychology to the promotion and maintenance of health, the prevention and treatment of illness, the identification of etiologic and diagnostic correlates of health, illness and related dysfunction, and the analysis and improvement of the health care system and health policy formation. 4 I N T R O D U C T I O N T O H E A LT H P S Y C H O L O G Y This definition emphasises the diversity of issues encompassed by the emerging discipline. There is also variety in the approaches brought to those issues. Some health psychologists would see themselves primarily as clinicians, others as psychophysiologists, and others still as cognitive psychologists; some will practise health psychology in the health care settings, others will teach and research in academic institutions—what unifies them is their interest in the areas delineated by Matarazzo and their approaches to these issues. Downloaded by [Saudi Digital Library] at 09:02 10 October 2017 Historical background The recognition of health psychology as a clearly designated field is very recent, as we have seen; however, many of the ideas and basic concepts have been around psychology for a great deal longer. The relationship between mind and body and the effect of one upon the other has always been a controversial topic amongst philosophers, psychologists and physiologists. Within psychology, the development of the study of psychosomatic disorders owes much to Freud. Psychologists such as Dunbar (1943), Ruesch (1948) and Alexander (1950) attempted to relate distinct personality types to particular diseases with an implicit causation hypothesis. Work of this type has become more sophisticated in its approach and the chapters in the book on coronary heart disease and cancer are illustrative, and critical, of this orientation. This approach has been largely abandoned by health psychologists in favour of more behavioural or biological approaches which seek to employ inter ventions derived from behavioural medicine (see the chapters concerning pain (Chapter 6) and hypertension (Chapter 10) as exles of this). Another important aspect in the development of health psychology has been the changing patterns of illness and disease. If we were to compare 1898 with 1998 we would see that contagious and infectious diseases now contribute minimally to illness and death in the Western world, and other illnesses have become more frequent and are of a different nature. Major breakthroughs in science have reduced the prevalence of diseases such as smallpox, rubella, influenza and polio in the Western world; more deaths are caused now by heart disease, cancer and strokes. Recent studies and theories suggest that these diseases are, in part, a by-product of changes in lifestyles in the twentieth century. Psychologists can be instrumental in investigating and influencing lifestyles and behaviours which are conducive or detrimental to good health. The chapters in this book on AIDS (Chapter 8) and coronary heart disease (Chapter 11) illustrate areas where such interventions are being attempted. Increasingly, then, the major causes of death are those in which so-called behavioural pathogens are the single most important factor. Behavioural pathogens are the personal habits and lifestyle behaviours, such as smoking and excessive drinking, which can influence the onset and course of disease. It is not just the diseases of the ‘developed’ world which can be affected by behaviour and attitude: combating malaria, schistomiasis and other diseases endemic in different parts of the world can also be greatly helped by psychological input into caigns to change behaviour. As people the world over live longer, the long-term effects of what Matarazzo (1983) calls ‘a lifetime of behavioural mismanagement’ can begin to 5 INTRODUCTION express themselves as diseases such as lung cancer, and heart and liver dysfunctions. Health behaviours Downloaded by [Saudi Digital Library] at 09:02 10 October 2017 We will now look at behaviours which can be part of maintaining a healthy lifestyle and avoiding ill health. These are known as (protective) health behaviours. Harris and Guten (1979) conducted an exploratory study of 1250 residents in Greater Cleveland, USA. Residents were asked: What are the three most important things that you do to protect your health? Following this free recall, they were presented with statements on cards which described health behaviours and were asked to sort them into those that they did and those that they did not practise. Cluster analyses performed on these data produced categories to account for the various responses obtained by both methods. Categories of health protective behaviours thus found were: • • • • • environmental hazard avoidance—avoiding areas of pollution or crime; harmful substance avoidance—not smoking or drinking alcohol; health practices—sleeping enough, eating sensibly and so forth; preventive health care—dental check-ups, smear tests; safety practices—repairing things, keeping first aid kits and emergency telephone numbers handy. Other studies carried out by Pill and Stott (1986) and Amir (1987) confirm these findings that people can identify behaviours which they carry out to protect health. Amir (1987) developed the General Preventive Health Behaviours (GPHB) Checklist. It consists of twenty-nine items which were selected to represent a range of behaviours thought to be relevant to a British population. Amir carried out the study on elderly (65–75 years) Scottish people and found the following items to be endorsed by more than 90 per cent of respondents: • • • • • • • • Avoid drinking and driving Wear a seat-belt when in the car Do all things in moderation Get enough relaxation Check the safety of electrical appliances Avoid overworking Fix broken equipment around the home Eat sensibly At the other end of the spectrum, only 10 per cent reported taking dietary supplements or vitamins, and only 12 per cent regularly got a dental check-up. It is likely that these percentages would look very different in different age groups (see the discussion topic at the end of this chapter). There is thus a common-sense notion that a relationship exists between good health and personal habits. Plato said, ‘where temperance is, there health is speedily imparted’. Many groups have codified ‘good’ living habits into their 6 I N T R O D U C T I O N T O H E A LT H P S Y C H O L O G Y Downloaded by [Saudi Digital Library] at 09:02 10 October 2017 religions and there is strong evidence of the outcome of healthy living and abstinence in such communities: Mormons in Utah have a 30 per cent lower incidence of most cancers than the general population of the USA, and Seventhday Adventists have 25 per cent fewer hospital admissions for malignancies (Matarazzo, 1983). Such statistics are powerful indicators that personal lifestyles do much to ensure healthy bodies. This idea was first studied systematically by a much cited study carried out in Alameda County, California and reported initially by Belloc and Breslow (1972). They asked 6928 county residents which of the following seven health behaviours they practised regularly: • • • • • • • not smoking; having breakfast each day; having no more than one or two alcoholic drinks each day; taking regular exercise; sleeping seven to eight hours per night; not eating between meals; being no more than 10 per cent overweight. They also measured the residents’ health status via a number of illnessrelated questions: for exle, how many days they had taken off from work due to sickness in the previous twelve months. They were also interested in physical, mental and social health which they defined as ‘the degree to which individuals were functioning members of their community’. Although criticisms have been made of this study, most notably the lack of independence between the questions, some strong and well-replicated relationships were demonstrated. A health habit is a health behaviour which is well established and often carried out semiautomatically: do you actually decide each morning and evening to clean your teeth, or do you ‘just do it? Adults in the study who engaged in most of the health habits reported themselves to be healthier than those who engaged in few or none. A follow-up study nine-and-a-half years later showed that mortality rates were significantly lower for both men and women who practised the seven healthy habits. Men who had all seven healthy habits had only 23 per cent of the mortality rate of men who carried out none or fewer than three health habits (Breslow and Enstrom, 1980). There were also clear links between physical, mental and social health. These findings reinforce the holistic notion of health proposed by the WHO as a composite of effective functioning, whether physically, mentally or socially. This original Californian cohort has been studied for twenty-five years. A survey in 1982, seventeen years after the study first began, considered those individuals who had been at least 60 years old at the time of the first survey. It was found that not smoking, taking physical activity, and regular breakfast eating were strong predictors of their mortality (Schoenborn, 1993). The Alameda Study reinforced the idea of ‘moderation in all things’ as the basis of good health. It also emphasised the role of social and mental aspects in achieving good physical health. Although most of us are familiar with the need to engage in preventive health behaviours, few of us actually do so. Berg (1976) has stressed that most 7 INTRODUCTION Downloaded by [Saudi Digital Library] at 09:02 10 October 2017 people are aware of which health behaviours should be engaged in; however, they frequently do not do so, and furthermore do engage in activities which they know to be harmful to their health. It is this cantankerousness which psychologists have spent a great deal of time examining. The dilemma or challenge then is how best to encourage, persuade or coerce people into adopting the healthy habits which it is believed are good for them. This enterprise carries values and expectations which will be examined in the final chapter. The dilemma for health psychologists is to explain why some or many people do not do what they know is in their own best interests to do; and why some people are more amenable to the adoption of healthy habits than others. A consistent focus has been the role of knowledge in changing behaviours. People need to be informed of the risks to themselves that certain behaviours (or non-behaviours) can engender. Having been apprised of the risks they will then decide, so the argument goes, in a rational manner, to modify their behaviours in the direction of greater health promotion and protection. Studies examining a range of issues relevant to health such as smoking, drug-taking, medical checks and adopting safer sex have fairly consistently shown that knowledge, by itself, does not lead to behaviour change. Kelley (1979) examined the role of media in improving public health. He pointed out that the use of safety-belts in cars greatly reduces the probability of death and injury following crashes. However, the availability of seat-belts in cars does not guarantee their use. A study conducted in the USA in 1968 recorded only 6.3 per cent of car drivers wearing seat-belts in a city area. Kelley attempted to design and execute a definitive test of mass media effectiveness in increasing seat-belt use. He was able to utilise cable television such that he could have a number of households which would receive advertisements concerning seat-belt use, and another, equivalent number of households which would not. He used six different advertisements, produced professionally, and shown at specific times designed to target specific audiences. The advertisements were shown regularly over a period of nine months. He estimated that the average television viewer in the experimental group saw one or another of the messages two or three times a week over the test period. Observers positioned at designated sites within the area under study recorded seat-belt use and the car licence plate which enabled a trace to be made to indicate which of the two cable television companies was available to that person’s house. Kelley’s conclusion was depressing: ‘The results were clearcut. The caign had no effect whatsoever on seat belt use.’ There were no significant differences between drivers from households which had received the messages and drivers from the control households. Nor did the drivers from the test group change their seat-belt wearing at all across the test period. Kelley argues very forcefully from this study that mass media caigns are ineffective and an inefficient means of changing health behaviours. So what else is required, other than knowledge, to persuade people to look after their health? We will now examine suggestions for other factors which could influence health behaviour. 8 I N T R O D U C T I O N T O H E A LT H P S Y C H O L O G Y Downloaded by [Saudi Digital Library] at 09:02 10 October 2017 Models of health behaviour Early studies of protective health focused upon demographic variables such as age, race and socioeconomic class as determinants of the adoption and practice of health behaviours. This research resulted in descriptions of population groups which did or did not engage in health behaviours. These findings were sometimes contradictory and often did not ser ve any great purpose—one cannot change one’s age, sex or race and there is only limited opportunity to change occupation or alter income. Consequently research has shifted to structural variables such as the cost or complexity of the behaviour, with a view to improving the adoption and practice of preventive health behaviours. There are several theories or models which have evolved in this context. All the models share a common framework in that they exemplify a biopsychosocial approach to health. Such an approach recognises the biological and genetic bases of many illnesses, acknowledges the role of psychological elements such as beliefs, behaviours and cognitions in the development of all illnesses, and recognises that the social, economic and cultural setting will have great impact on health. This approach, first developed by Engel (1977), underpins much of health psychology and will be apparent throughout this book. We will now consider in detail some of the more important models and note their shared characteristics. The health belief model (HBM) This is probably the ‘oldest’ and best known of the models of health behaviour. It is the one against which more recent models have been developed. This model was specified initially by Rosenstock (1966) and was modified by Becker and Maiman (1975). It attempts to explain both health behaviour and compliance. It should be useful in predicting both health behaviour before illness, such as screening for cancer, and compliance with medical regimens once ill. Thus, both sick role behaviour and preventive behaviours should be capable of being predicted. The model proposes that a person’s likelihood of engaging in healthrelated behaviours is a function of several dimensions. An outline of the model is presented in Figure 1.1. It proposes that for a person to take preventive action against a disease, that person must: • • • • • feel personally susceptible to the disease (perceived susceptibility); feel that the disease would have at least moderately serious consequences (perceived severity); feel that preventive behaviour would be beneficial either by preventing the disease, or by lessening its severity (perceived benefits); that barriers, such as pain, embarrassment or expense (costs) should not outweigh the perceived benefits of the proposed health action in order for the preventive health behaviour to occur; that cues to action may trigger a consideration of the proposed health action. 9 Downloaded by [Saudi Digital Library] at 09:02 10 October 2017 INTRODUCTION Figure 1.1 Health belief model Source: Becker and Maiman (1975). Copyright Lippincott-Raven Publishers. The model has been used with some success to predict the adoption of several different health behaviours, including vaccinations, screening for cancer and contraceptive behaviour (Harrison et al., 1992; Herold, 1983; Janz and Becker, 1984). For some behaviours, perceived severity may be less important for preventive behaviours than either perceived vulnerability or cost-benefit considerations (Cleary, 1987). There can be problems of response bias when questionnaires which have operationalised the HBM construct are used. This is discussed by Sheeran and Orbell (1996), who recommend several ways of avoiding this problem. Harrison et al.’s meta-analytic review of HBM in 1992 originally identified 234 published studies. Of this large number, however, only sixteen had examined all the major components of the model and had included reliability checks. Harrison et al. then converted effect sizes of the sixteen studies into correlation coefficients and calculated correlations for susceptibility, severity, benefits and barriers. Whilst all the correlations were statistically 10 I N T R O D U C T I O N T O H E A LT H P S Y C H O L O G Y Downloaded by [Saudi Digital Library] at 09:02 10 October 2017 significant they were also rather small, accounting for less than 4 per cent of the variances across the studies. Despite the fact that the model has been around for more than two decades, it is rarely used carefully and with sufficient reliability to be confident of its results. The major problems with it as an account of health behaviours are that it assumes rationality as the basis for an individual’s decision making, and downplays the role of emotions, for exle, fear and anxiety. It also tends to assume that beliefs are static and, once formed, fairly fixed. Other models which have been developed from the HBM have attempted to incorporate some of these additional elements. Protection motivation theory Rogers (1984) examined health behaviours from the point of view of motivational factors; thus it built on HBM by incorporating motivational elements into its basic structure. The protection motivation model suggests that motivation to protect oneself from a health threat is based on four beliefs: • • • • that the threat is severe (magnitude); that one is vulnerable to the threat (likelihood); that one can perform the behaviour required to protect against the threat (self-efficacy); that the response made will be effective (response-efficacy). Early research emphasised fear as a motivational factor but Rogers now suggests instead that attempts need to be directed at all four of the elements described above to achieve effective change. It is not clear which of the four elements is more important than the others, nor how to develop a caign which can adequately address all elements simultaneously. Leventhal’s self-regulatory model A rather different approach is that of Leventhal and co-workers who have developed a model of illness behaviour and cognitions. This could be characterised as a problem-solving model since it conceptualises the individual as an active problem solver whose behaviour reflects an attempt to close a perceived gap between current status and a goal, or ideal state. Behaviour depends on the individual’s cognitive representations of his or her current health status and the goal state, plans for changing the current state, and techniques or rules for assessing progress. Leventhal’s self-regulatory model of illness (Leventhal and Cameron, 1987) defines three stages which regulate behaviour. These stages are: • Interpretation of the health threat—this concerns the cognitive representation of the threat, which includes dimensions such as symptom perceptions, and social messages such as potential causes or possible consequences. 11 Downloaded by [Saudi Digital Library] at 09:02 10 October 2017 INTRODUCTION Figure 1.2 Leventhal’s self-regulatory model of illness behaviour Source: Leventhal and Cameron (1987). Copyright Elsevier Science Ireland Ltd. • • An action plan or coping strategy—this may take a variety of forms; the major ones are an approach coping strategy which would include seeking medical attention, self-prescribing, discussing the symptoms with others; or an avoidance strategy, i.e. denial that there might be a problem and wishing it away. The last stage is the appraisal stage, in which the individual utilises specific criteria to gauge the success of coping actions, with perceptions of insufficient progress leading to modifications. The model is presented in diagrammatic form in Figure 1.2. The selfregulation comes from the individual’s attempts to maintain the status quo and return to the ‘normal’ state of health. Emotional reactions can be evoked at any stage; cultural or social differences, for instance in symptom perception or illness expectations, can lead to dif fering representations and different coping structures. An attractive feature of this type of model is that it is active: it stresses the individual and how that person can operate and reflect on his or her actions. This, though, is also its potential weakness; it has not been as amenable to testing, particularly through questionnaire construction, as has the health belief model. The theory of planned behaviour (TPB) The theor y of planned behaviour derives from social psychology and is a development of an earlier theory of reasoned action. Both models emphasise the role of decision making and seek to explain the suggested relationships between attitudes and behaviours. The theory of planned behaviour has become a major model for health promotion. The models have as their central premise the notion that people make decisions about their behaviour on the basis of a 12 Downloaded by [Saudi Digital Library] at 09:02 10 October 2017 I N T R O D U C T I O N T O H E A LT H P S Y C H O L O G Y Figure 1.3 Theory of planned behaviour reasonable consideration of the available evidence. TPB stresses that behaviour is planned and that the planning is, in part, a function of an individual’s intentions. The model identifies intention as the most immediate determinant of behaviour (Ajzen and Madden, 1986; Fishbein and Ajzen, 1975). Intentions are themselves a function of three separate elements—privately held attitudes towards the particular behaviour, a perception of socially determined norms that represent a person’s belief that others think he or she should behave in a certain way, and perceived behavioural control, which is a person’s belief that they can carry out the planned behaviour, that they have the necessary skills and abilities and that they can overcome potential external barriers (Figure 1.3). The model attaches values to each of these factors. The particular values attached to each factor will depend upon the individual’s beliefs and thus in many ways this model is similar to the health belief model. One difficulty with this model is that it identifies a direct link between intentions and behaviours, but intentions are not always translated into actions. Even when an individual holds an intention towards some behaviour, action does not necessarily result. There may be one or more reasons for not carrying out an intention to act in a particular way that is perceived as beneficial. The action may not be possible in a particular situation or at a particular time, it may be difficult or time consuming or it may simply be suppressed. From the point of view of the promotion of health behaviours, much greater consideration needs to be given to the impact of situational influences of this kind upon adherence to an intention to act in accordance with prevention (see Abraham and Sheeran (1993) for a fuller discussion of this point). 13 INTRODUCTION Schwarzer’s health action process approach (HAPA) Downloaded by [Saudi Digital Library] at 09:02 10 October 2017 Schwarzer has been critical of the TPB in that it includes no temporal element and hence is ‘static’. He has developed his own model which explores the factors that facilitate the adoption and maintenance of health behaviours. Its basic notion is that ‘the adoption, initiation, and maintenance of health behaviours must be explicitly conceived as a process that consists of at least a motivation phase and a volition phase. The latter might be further subdivided into a planning phase, action phase and maintenance phase’ (Schwarzer and Fuchs, 1996). See Figure 1.4 for an outline of the model. Schwarzer stresses that perceived self-efficacy (see p. 17) plays a crucial role at all stages of the model. During the motivation phase the individual develops an intention, and this intention is predicted by self-efficacy and outcome expectancies (‘I am confident that I can lose weight and I know that losing weight will improve my health’). Schwarzer suggests that outcome expectancies precede self-efficacy because people make assumptions about outcomes before they ask themselves whether they can perform the action. They then carry out an appraisal of threat or risk— a little like the perceived severity element of HBM. Schwarzer suggests that this element may be minimal in many cases and specifically that fear appeals may have only limited value. ‘It is common knowledge that good intentions do not necessarily guarantee corresponding actions’ (Schwarzer and Fuchs, 1996): thus the right-hand section of Figure 1.4 consists of three levels: cognitive, behavioural and situational. Here again, self-efficacy plays a role in determining the amount of effort invested in the action and the perseverance with the action phase. Figure 1.4 Schwarzer’s health action process approach Source: Schwarzer and Fuchs (1996) 14 I N T R O D U C T I O N T O H E A LT H P S Y C H O L O G Y It should be noted that all these models tend to rely on a model of a person as a rational decision maker, subject to motivational forces but essentially making decisions and following them through. Once again, the roles of emotions and of situational variables (for exle chocolate in the cupboard, wine in the fridge) are relatively underplayed. Downloaded by [Saudi Digital Library] at 09:02 10 October 2017 The transtheoretical model Finally, a rather dif ferent approach to health behaviours is that of the transtheoretical model developed by Prochaska and DiClemente (1983, 1992) as an integrative and comprehensive model of behaviour change. They suggest that people move through a series of stages in changing their behaviour. They label them precontemplation, contemplation, preparation, action and maintenance. Using studies on how people begin and maintain an exercise programme as an exle, the stages would be • • • • • Precontemplation: a period during which a person is not seriously considering the need for regular exercise: ‘No problems, I’m fine as I am.’ Contemplation: a period during which a person is seriously considering exercise: ‘I can’t do what I used to; I need to get fitter.’ Preparation: a period during which a person seriously thinks about beginning an exercise programme, say, during the next month: ‘That new gym has opened up nearby; I’ll buy myself a track suit.’ Action: a period ranging from nought to six months during which the person is actually exercising ‘three times a week in the gym—I’m feeling good.’ Maintenance: a period beginning six months after the start of the exercise programme: ‘I’m attending regularly, and rarely miss a session.’ Thus the model is temporal and describes the process of change rather than only identifying the precursors to that behavioural change. The decision-making element associated with the model derives from Janis and Mann’s conflict model (1977), which involves a consideration of benefits and costs (pros and cons) associated with a behavioural change. Prochaska et al. (1994b) applied the stages of change to a number of problem behaviours which included: smoking cessation, weight control, quitting cocaine, using condoms, applying sunscreens, and others. Twelve separate sles were drawn on for each of the problem behaviours, yielding a total sle size of 3858. Looking at costs and benefits of behavioural change, the study showed that for all problem behaviours, the cons of changing were higher than the pros for those respondents in the precontemplation stage. The opposite was true for those respondents in the action stage. For seven of the twelve behaviours the cross-over in the balance between pros and cons occurred during the contemplation stage; for the other five behaviours it occurred during the action stage. This suggests that a costs-benefits analysis fits well within this approach. Prochaska et al. (1994a) review studies on the transtheoretical model of change and HIV prevention and conclude that the model is also generalisable 15 INTRODUCTION to HIV prevention. They highlight the importance of distinguishing between main sexual partners and casual sexual partners and suggest different factors are operating in decisions to use condoms with these two groups (see Chapters 8 and 9 for a discussion of the issues of contraception and HIV prevention). Comparing the models Downloaded by [Saudi Digital Library] at 09:02 10 October 2017 There is a clear need for further empirical studies that test these and other models for the adoption of preventive health behaviours, since interventions based upon them have implicitly accepted their assumptions. If the determinants of precautionary behaviours could be identified this would be a significant step forward in caigns against behavioural diseases such as AIDS, or smokingrelated illnesses. There is little doubt that the principal variables identified by these models—perceived risk, perceived severity of the disease, perceived effectiveness of precautions, social norms, self-efficacy and cost-benefit payoff— are important predictors of preventive health behaviours of many kinds. However, the value attached to each element remains uncertain. Individual differences People vary in how they respond to a health threat or prevention measure. Some of this variation can be accounted for by considering person variables. These variables should begin to account for the differences between people in how they respond to similar health threats. Health locus of control In the mid-1960s the concept of ‘locus of control’ was introduced by Rotter and others (Rotter, 1966). This grew out of a social learning tradition which considered the expectations of individuals and how they related to reinforcements. Individuals with an internal locus of control were more likely to believe that reinforcements were contingent upon their own efforts, whereas those with an external locus of control were likely to regard their life as determined largely by external forces such as fate or ‘powerful others’. A development of this broad construct of locus of control was the health locus of control scale constructed by Wallston et al. (1978). Questions reflected the three factors mentioned above—an internal focus for health: ‘I am in control of my health’; the powerful others factor: ‘Whenever I do not feel well I should consult a health professional’, and the role of fate: ‘Luck plays a big part in determining how soon I will recover from an illness.’ There is some evidence (reviewed by Wallston and Wallston in 1984) that high ‘internal scorers’ carried out a greater range and number of health behaviours; but differences between internals and externals are not diverse, and the amount of variance accounted for by this measure is frequently small (Pitts et al. 1991). Furnham and Steele (1993) reviewed the outcomes of locus of control questionnaires, including those 16 Downloaded by [Saudi Digital Library] at 09:02 10 October 2017 I N T R O D U C T I O N T O H E A LT H P S Y C H O L O G Y for health, and also found that they accounted for only a low amount of variance. A number of disease-specific questionnaires has been developed; Bradley and colleagues, for exle, have considered locus of control in relation to diabetes (Bradley et al. 1984, 1990); others have applied the approach to cancer (Pruyn et al., 1988), and to hypertension (Stanton, 1987). Furnham and Steele point out that the critical practical issue for further research is whether locus of control beliefs can be altered by interventions or whether they are more or less ‘fixed’ traits. Many researchers make the point that the aim of devising a scale is to identify those people who hold maladaptive beliefs. Very little, however, has developed from these identifications. We have already encountered the next variable to be considered in models of health behaviour. Self-efficacy Bandura, again from a social learning perspective, has suggested that self-efficacy is a major factor to be considered in accounting for differences in health behaviours (Bandura, 1977, 1986). It has been applied to helping people to quit smoking and to persuading people to indulge in physical exercise. It examines people’s beliefs in their own abilities with questions such as: ‘I am confident I could deal efficiently with unexpected events’, or ‘I can always manage to solve difficult problems if I try hard enough’. It has been studied both as a behaviour specific to a narrow situation and as a more general trait construct. The model has recently been applied to condom use by Wulfert and Wan (1993). They developed an outline of a model which uses self-efficacy as a common pathway to integrate the effects of several cognitive variables that might predict condom use. The first of these variables is sexual attitudes, the second is outcome expectancies, i.e. what would be the effect of using a condom. Comparison and influences from a peer group were seen as important, as were knowledge and perceived vulnerability about AIDS. The results from this study support the role of self-efficacy as a mediating variable between factors such as peer influence, knowledge and perceived vulnerability and an actual behaviour. Such studies have prompted attempts to enhance self-efficacy beliefs, especially among young adults. Schwarzer has developed a general self-efficacy scale which aims to measure a broad and stable sense of personal competence to deal effectively with challenges in one’s life from a variety of sources. Schwarzer contrasts self-efficacy with the concept of optimism described below. Self-efficacy is restricted to one’s beliefs about personal resources, focusing particularly on competence; in contrast, optimism is a broader construct which may incorporate a number of other elements, for exle luck. That said, clearly the relationship between the two constructs is ver y close. Schwarzer has translated the self-efficacy scale into several languages. Cross-cultural comparisons can be very tricky; but there is an interesting finding which emerges from a comparison of the studies in different countries. Sometimes gender differences are found, and sometimes not; but in no country yet studied have women been found to score higher than men (Schwarzer et al., 1997). As Schwarzer et al. suggest, research is now needed to 17 INTRODUCTION establish whether the scale itself is gender-biased or whether the construct of self-efficacy favours men. Optimism Downloaded by [Saudi Digital Library] at 09:02 10 October 2017 A relatively reliable finding in health psychology is that when asked to compare one’s own risk of something negative against the risk of others like me, I will tend to underestimate my own risk against others’. Judgements are required for statements such as ‘Compared with others of my age, my chances of developing …are greater than/the same as/less than them.’ The usual response is to judge oneself at less risk of almost any health threat than one’s contemporaries. It appears that most people engage in this social comparison bias with regard to many health issues such as risks of lung cancer, AIDS, traffic accident or heart disease. There is also evidence that this kind of optimism is particularly characteristic of adolescence, where it is known as ‘adolescent invulnerability’ (Quadrel et al., 1993). These biases are dysfunctional in terms of health behaviours and health promotion. They are likely to act as defence strategies against behavioural change: ‘Others need to change their behaviour, not me.’ Other kinds of optimism are, however, more adaptive because they imply coping strategies and behavioural change. Researchers such as Sheier and Carver (1992) have shown that optimists have better health and practise more health behaviours than pessimists; this is possibly linked to the fact that optimists expect good outcomes and hence cope better with short-term distress or discomfort. The links between optimism and self-ef ficacy are close; each construct is measured by questionnaires which are rarely unidimensional. Dispositional optimism is measured by the life orientation test (Sheier and Carver, 1985). This is a short, twelve-item test, which taps people’s approach to life with statements like ‘I always look on the bright side’ or ‘I hardly ever expect things to go my way.’ Wallston (1994) has offered an interesting distinction between ‘cautious’ and ‘cockeyed’ optimism. The cautious optimist is ‘pretty much in touch with reality’; being fairly confident that things will turn out right, the person nevertheless does everything in his or her power to ensure that it does. Confident of success in my driving test I nevertheless revise the Highway Code the night before. The ‘cockeyed optimist’—in the words of Rogers and Hammerstein—is ‘Stuck like a dope with this thing called hope’, who lives in a world of illusion and hardly raises a finger to help bring about his or her desired outcomes. In the context of health care this results in little change towards healthy habits and avoiding unhealthy ones. Given this, one would predict a cur vilinear relationship between optimism and health behaviours with only the cautious optimism items predicting uptake and maintenance of health behaviour. Optimism has generated a great deal of research and is likely to remain a key variable in future work. 18 I N T R O D U C T I O N T O H E A LT H P S Y C H O L O G Y Downloaded by [Saudi Digital Library] at 09:02 10 October 2017 Doing health psychology research Next we need to consider the ways in which data and evidence are gathered in health psychology. Many of the methods are similar to other areas of psychology—experimental tests undertaken in a carefully controlled setting, psychophysiological measures which are related to behaviour, observational studies, are all exles of standard techniques. However, there are a few methods which are used in health research and are less commonly encountered by those with a background in psychology. Some of these will be introduced briefly here. Research in health psychology shares many characteristics with all psychological research. These are: that the research usually originates with a question; that it demands clear articulation of a goal, and that it requires a specific plan or procedure. Often a large problem, for exle ‘How can we best help patients recover from surgery?’, becomes divided into smaller problems: ‘Which kind of information provision before surgery aids recovery?’ Health psychology research is also guided by hypotheses and endeavours to use objective measures. A method frequently used in health research is that of a clinical trial, in which one approach (usually treatment) is compared with another to see which is better. It is imperative that such comparisons are fair and one of the basic ways in which this is achieved is by random allocation of people to one treatment or another. Such random allocation should ensure that any differences found between treatments are genuinely just that, i.e. treatment differences, and are not the outcome of a particular kind of person choosing one treatment over another. Randomised clinical trials are often regarded as ‘the gold standard’ for health research against which other studies may be assessed. Cohort trials are used when a group of people is followed through an experience (treatment) to see how they may change or improve over time. This is a particularly interesting way of examining a chronic condition, or the outcome of a particular intervention or treatment, say, chemotherapy. It is still important, though, that there should be a comparison group against which changes in the cohort may be compared. This is the only way in which we can be sure that the changes observed in the cohort are not simply the result of time passing. The survey is probably the most widely used, and abused, method in psychological research. Surveys seek to examine people’s attitudes, opinions or beliefs about a health issue. Frequently people are asked to report on their own behaviour. It is important that those surveyed can, in some sense, be compared with a wider group of people. We need to know how people were selected for the survey, what the response rate was and whether the findings can be generalised. Finally, the relationship between self-report and behaviour needs to be carefully examined. Focus groups, favoured by political parties and market researchers, are being used increasingly frequently in health research. Focus groups should allow us to gain a greater psychological understanding of human experience by gathering together the opinions, beliefs and attitudes of between six and twelve individuals who are similar in some way. They are brought together to discuss a specific set 19 INTRODUCTION Downloaded by [Saudi Digital Library] at 09:02 10 October 2017 of issues. Focus groups rely on the dynamics of group interaction to stimulate the thinking and contributions of group members. This explicit use of group dynamics is what distinguishes the technique from more general ‘group interviews’. Focus groups have been used to investigate a wide range of issues such as people’s views on contraception (Barker and Rich, 1992), drink driving (Basch et al., 1989), and media coverage of AIDS (Kitzinger, 1994). The focus must be clearly set—for exle via a short video. The group must ‘gel’—often achieved via introductions and sharing of common experiences/goals—and contributions must be encouraged, and opposing views as well as consensus examined. There is more than one way to cook a goose, and focus groups are frequently used in conjunction with other methods. Sometimes they are a first method and used as a preliminary tool, for exle, before designing a questionnaire. This enables the use of appropriate terms and words in the questionnaire, which otherwise might be imposed by the researcher. Focus groups are usually used when issues are poorly defined, when the quality of information to be elicited is vital and participants for the groups can be recruited relatively easily. Epidemiology is the study of how often diseases occur in different groups of people and how disease outcomes can be measured in relation to a population at risk. This population is defined as those people, sick or well, who would be counted as cases if they contracted the disease. A study population might be defined by a shared characteristic such as geographical location, as in the Alameda County study (Belloc and Breslow, 1972), by occupation, as we shall see in the Whitehall studies (Chapter 16), or by diagnosis, i.e. people in a given location who were first diagnosed with a disease in a given period of time. It is important to remember that, unlike clinical observations which relate to individuals, epidemiological observations determine decisions about groups. Its conclusions are frequently based on comparisons between groups of people. It may also estimate the relative risk of a person contracting a disorder by comparing incidences. However, this cannot and does not predict with any degree of certainty that an individual will develop a disease or disorder. You will encounter the results of epidemiological surveys throughout this book. Finally, there are some general questions which should be asked of any research: these (adapted from Crombie, 1996) can be characterised as follows: • • • • Was the research worth doing? Are the findings substantial or trivial? Do they have theoretical and/or practical import? Are we the better for them having been done? Ethics in health psychology research Ethical issues must inform all research, but there are particular responsibilities within the area of health psychology. There is nearly always some conflict between the needs of research and the needs of individuals who are ‘being researched’. The following quotation makes this tension explicit: Social scientists…have a genuine obligation to devise protections for the 20 I N T R O D U C T I O N T O H E A LT H P S Y C H O L O G Y Downloaded by [Saudi Digital Library] at 09:02 10 October 2017 right of privacy and to avoid mere psychic voyeurism. At the same time they have a compelling obligation to collect data: there is an obvious conflict between the need of society to know and the right of the individual to dignity and privacy. (Stagner, 1967) Many of the participants in health research are especially ‘vulnerable’: they may have just received bad news, they may be anxious about impending treatment, they may be children. As such, we have special responsibilities to ensure that we respect their rights when carrying out research; there is a basic edict which is: do no harm. All health research should require that participants give informed consent; in other words, that participants in the research understand what it is that is being asked of them and formally agree to participate. Issues of understanding become central to this process. Participants in research must also understand that the research is separate from their treatment and that a refusal to participate will not jeopardise their chances of the best treatment available. Research that is carried out in medical settings can be particularly problematic in establishing this. Anonymity and/or confidentiality are critical in settings where information can be passed to a fairly wide range of people, and where it can be potentially damaging or embarrassing for the participants. Finally, issues of creating a comparison group can be extremely difficult to justify to oneself and to participants. If we believe that a particular intervention may be beneficial to patients, how can we withhold it from randomly selected patients allocated to the control condition, to establish its efficacy? This dilemma is usually resolved either by comparing different possible treatments—not really a resolution of the difficulty, but at least countering the ‘no treatment’ issue; or by offering the treatment to the ‘control’ or comparison group following completion of the study—again hardly a resolution of the dilemma. Would you withhold treatment from participants to achieve a comparison group? As researchers in the area of health psychology, we must be aware of these problems and ensure that the research we carry out follows the highest possible ethical standards. Other chapters in this book will enlarge on much of what has been covered here. Specific problems and issues will be examined in detail in the light of the theories and models described above. We need, though, having examined some of the areas of interest to health psychologists, to consider further its future as a discipline. Marteau and Johnston (1987) have sounded a warning note about the development of the field. They caution that ‘the relative neglect of psychological models and paradigms in work considered under the rubric of health psychology, results in approaches to problems in clinical and research contexts that owe more to a medical than a psychological perspective.’ Johnston (1988) also suggests that at least five separate kinds of literature on health psychology appear to be developing, according to the problem studied and the journal in which the research is published. It is becoming increasingly difficult for any one person to keep abreast of the literature on the diverse areas of interest that are encompassed by health psychology. It must be hoped that increasingly research and theory building for one particular health issue will more clearly 21 INTRODUCTION inform and guide research in other related topics, and that psychological models of health behaviour will give rise to effective interventions for promoting health. HEALTH AND BEHAVIOUR • • • Downloaded by [Saudi Digital Library] at 09:02 10 October 2017 • • • • Make a list of five things you do to protect your health. Now list five things you do which are injurious to your health. What do the two lists tell you about health protective behaviours and behavioural pathogens? How would you change two of the behaviours on the ‘dangerous list’? Are there barriers to making that change? What could you do to overcome these? How does your analysis compare with any one model of health behaviour outlined in this chapter? You may like to compare your lists with that of another person who is different in age or gender from you. Why are your lists similar or different? Key point summary • • • • • 22 Any activity which is related to health, illness, the health care system or health policy is within the domain of health psychology. Certain health behaviours or habits are related to good health and others can be predictors of mortality. There are wide differences between people in the extent to which they practise such health behaviours. Theoretical models incorporate concepts such as risk perception, severity, barriers and motivational aspects which come together with any particular model as an explanation of the process of adopting healthy behaviours, or avoiding unhealthy ones. Individual differences are important in predicting health behaviour. Constructs such as self-efficacy, locus of control and optimism have been found to be useful in explaining people’s behaviour. Health psychologists have a duty to ensure that participants in their studies are protected from harm and able to make informed decisions about their participation. I N T R O D U C T I O N T O H E A LT H P S Y C H O L O G Y Downloaded by [Saudi Digital Library] at 09:02 10 October 2017 Further reading Conner, M. and Norman, P. (1996) Predicting Health Behaviour. Buckingham, Open University Press. This book provides a review of the major models of health behaviour outlined in this chapter and gives good coverage of relevant studies and criticisms of the models. Karoly, P. (1991) Measurement Strategies in Health Psychology. London, Wiley. This is the standard textbook outlining the variety of measures used in health psychology . Nicolson, P. (1993) A day in the life of a Health Psychologist. The Psychologist, 6 (11), 505–509. This article gives an idea of what it is like to work as a health psychologist and the kinds of problems encountered. 23 Downloaded by [Saudi Digital Library] at 09:02 10 October 2017 Downloaded by [Saudi Digital Library] at 09:02 10 October 2017 Psychophysiology, health and illness Keith Phillips Introduction Organisation of the nervous system Central nervous system Peripheral nervous system Neuroendocrine and neuroimmunological systems Recording psychophysiological responses Recording bioelectric responses Ambulatory recordings Biochemical recordings Psychophysiology and health psychology Biopsychosocial models of disease Psychophysiological treatment of illness Biofeedback Principles of biofeedback training Clinical applications of biofeedback Biofeedback and reactions to stressors Is biofeedback effective clinically? Methodological issues Biofeedback in combined therapies Key point summary Further reading 26 26 26 27 29 31 32 33 33 34 35 36 36 36 38 41 42 43 44 45 46 Chapter 2 Chapter 2 25 INTRODUCTION Introduction This chapter briefly describes the structure and organisation of the nervous, endocrine and immunological systems and their roles in the regulation of physiological responses and behaviour. Techniques for recording and measuring responses of these systems are considered, and their roles in the determination of health and illness are discussed. Finally, the use of biofeedback as a clinical treatment for psychophysiological disorders is reviewed. Organisation of the nervous system Downloaded by [Saudi Digital Library] at 09:02 10 October 2017 The mammalian nervous system is made up of millions of individual nerve cells that are arranged in complex networks. Individual cells and groups of cells communicate with each other via special chemicals called neurotransmitters which trigger electrical events within these networks. These electrical events, called action potentials, are the code or language by which information is communicated within the system. In total, the nervous system can be regarded as a highly sophisticated communication system that enables interaction between an organism and the physical world in which it lives. The individual elements of this system are arranged within a highly structured organisation as one would expect of any communication network. When describing the organisation of the mammalian nervous system it is usual to identify its central and peripheral components. The central nervous system (CNS) comprises the brain and spinal cord; the peripheral nervous system (PNS) is the collection of nerves from the CNS to the periphery and from the periphery to the CNS. These nerves may be further subdivided into somatic and autonomic components. Before we consider each of these components it is important to appreciate that though they are described separately they are not separate systems in terms of their functions. The component structures are fully integrated with each other; changes that occur in the activity of the central nervous system will be accompanied by changes in the peripheral system and vice versa. The nervous system has evolved as a whole to allow behaving organisms to make successful adaptations to their environment. Ill health and disease may be regarded as indicators that successful adaptation has not been achieved. Central nervous system The central nervous system is made up of the brain and the spinal cord. These are developed from the same embryonic nerve tissues, are entirely interactive, and share an internal circulation of cerebrospinal fluid which protects against physical damage and provides a stable chemical environment to allow nerve cells to function. The CNS is enclosed by the bony coverings of the skull and vertebral column. In general terms, the CNS can be thought of as having an executive role in the control and regulation of behaviour. It receives information from the outside world, integrates current information with past experiences and instructs the responses of agents or effectors that 26 Downloaded by [Saudi Digital Library] at 09:02 10 October 2017 P S Y C H O P H Y S I O L O G Y, H E A LT H A N D I L L N E S S have effects upon behaviour. The obvious effector agents are the muscles of the skeletal system which cause our actions, but other effectors are the hormones secreted by the endocrine system and responses of the automatic ner vous system (ANS), such as changes in cardiac activity or electrical signals from the skin. Though the CNS prepares the instructions for changes in the activities of these effectors it does not deliver them; that is the job of the peripheral nervous system (PNS). Similarly, the PNS delivers to the CNS information from the outside world. Though the CNS may be considered to have an executive role, the regulation of behaviour is not entirely feudal since the operations of the CNS are influenced to a very large degree by feedback from the PNS. Peripheral nervous system The nerves of the PNS are divided into the somatic or autonomic nervous systems. The somatic system includes nerves from the sense organs (eyes, ears, skin, tongue and nose) which carry information from the outside world to the CNS. However the CNS is not simply a passive recipient of sensor y information; it has nerves connected to the sense organs which actively and selectively filter out information. As well as sensory nerves, the somatic system also includes motor nerves that travel from the CNS to the muscles whose contractions result in actions (behaviour). Again this is not a unilateral operation, as there are also sensory nerves from the muscles that relay the consequences of those actions back to the CNS. The interaction between the sensory and motor nerves of the somatic system and the CNS can be organised within the spinal cord alone, for exle for simple reflexes such as the knee-jerk reflex, but more usually it involves both the spinal cord and the various component structures of the brain. The ANS is divided into two divisions—the sympathetic and the parasympathetic divisions whose actions are opposite though complementary. Usually, though erroneously, these two divisions are described solely in terms of their effector nerves which travel from the CNS to the organs and glands within the body. These inner vations provide regulation of those visceral structures and hence regulation of the internal responses of the body. However, there are also sensory autonomic nerves carrying feedback from the viscera to the CNS. This of course is how we become aware of sensations such as emotional states, hunger pangs, or visceral pains. Thus the somatic and autonomic systems are similarly organised (see Figure 2.1). The sympathetic and parasympathetic systems have antagonistic actions yet play a combined role in regulating the internal environment of the body. Typically, each organ of the body receives inputs from both the sympathetic and parasympathetic divisions. However, the sympathetic system is diffuse and sympathetic nerves innervate several organs and glands. Thus when activated, a generalised sympathetic reaction is observed in many of the body’s internal organs. By contrast, the parasympathetic innervation is more discrete and individual organs have their own particular innervation, which allows more fractionated regulation of their responses. The sympathetic action causes 27 Downloaded by [Saudi Digital Library] at 09:02 10 October 2017 INTRODUCTION Figure 2.1 The organisation of the nervous system mobilisation of the body’s energy resources preparing the body for action. It is accompanied by multiple response changes including increased cardiac output, sweating, inhibition of digestion, increased blood flow to the muscles and dilation of the pupils. These responses prepare the body for action. This pattern of sympathetic activation is often referred to as the ‘fight or flight reaction’ and is considered to represent a reaction to stress (for further discussion see Evans, Chapter 3). The parasympathetic division exerts an opposite effect. It acts to conserve the body’s energy resources and its action is characterised by slowing of the heart, stimulation of saliva, digestive activities such as gastric secretions and intestinal peristalsis, and pupil constriction (see Table 2.1). Response regulation via these two divisions is highly sensitive, as they do not operate in an on-off fashion. Each division maintains some input to each of the various internal organs and the momentary response of any one organ is determined by the relative balance that exists between the two divisions at any given moment. To take a specific exle, the control of heart rate depends upon the relative inputs of sympathetic and parasympathetic innervations. When the heart rate alters, it is caused by a shift in the overall balance between the systems; for exle, a slowing of the heart rate could be caused by increasing the parasympathetic stimulation or equally well by maintaining the parasympathetic input at its current level but reducing the level of sympathetic input. The alterations of internal responding are sensed by internal sensory 28 P S Y C H O P H Y S I O L O G Y, H E A LT H A N D I L L N E S S Downloaded by [Saudi Digital Library] at 09:02 10 October 2017 TABLE 2.1 Antagonistic actions of the divisions of ANS receptors which provide feedback to the CNS and may result in the initiation of behaviours by the CNS. For exle, changes in gastric motility may be recognised as ‘hunger’, which may lead to initiation of actions to gather food whose consumption may eliminate the gastric contractions of the stomach: foodrelated behaviours will then cease. Within this closed loop there is no executive operator; merely mutual interdependence between the various components (see Brener, 1981). Despite its name it is also quite wrong to suppose that the ANS is an automatic system showing simply reflexive changes in activity. As the studies on biofeedback (see p. 36) have clearly demonstrated, the ANS is an adaptive system that is capable of learning to respond to the demands imposed by different environments. Neuroendocrine and neuroimmunological systems Neural systems are not the only means for regulating behaviour. The endocrine and immune systems also have prominent roles to play in maintaining health. These systems are well described by Rasmussen (1974) and Ader (1981) and are only briefly outlined here. The endocrine system further extends the functions of the nervous system and their actions are fully integrated with reciprocal influences upon each other. The system controls several glands within the body that secrete into the bloodstream chemical messengers called hormones which activate specific receptors in target organs which may show specific responses or may themselves be stimulated to produce other hormones and which in turn act upon other organs including the brain. Secretion of many of these hormones is regulated by trophic hormones released from the pituitary gland which has a significant function in integrating the release of dozens of other hormones within the body. This highly complex chemical regulation system is itself regulated by the CNS and in particular the hypothalamus and limbic system which are structures involved in the regulation of emotional and motivational states. The endocrine system is itself critically involved in basic biological functions including sexual differentiation and reproduction, metabolism and growth, emotional activation and reactions to 29 INTRODUCTION Downloaded by [Saudi Digital Library] at 09:02 10 October 2017 stressors. It would be impossible to review all the different neuroendocrine actions that exist within the body, but one exle of its actions is the reaction to stress (this is discussed further in Chapter 3). In humans there exists next to each kidney the adrenal gland which is made up of an outer cortex and an inner core, the adrenal medulla. Both of these are involved in the body’s reaction to stressors. The adrenal medulla is inner vated by the ANS and releases adrenalin and noradrenalin into the bloodstream. These circulating hormones prepare the body for action by increasing cardiac output and stimulating respiration. It has been found in both laboratory studies and real-life situations that psychosocial stressors such as facing danger, working under time pressure or admission to hospital cause increased output of adrenalin and noradrenalin. It may be that the extent of this response varies between individuals according to how they react to environmental demands, and it has been suggested that this differential response or reactivity may be associated with the development of certain diseases such as coronary heart disease (Manuck, 1994). The neuroendocrine system has long-acting influences upon the body. Once they have been released, hormones can circulate and have effects over substantial periods of time. Some act on receptors in the brain and influence behaviour directly; others have indirect influences via feedback from internal organs. The amounts of hormones circulating change in response to psychological influences, and at the same time it has been established that dysfunction of neuroendocrine systems such as the hypothalamic pituitary adrenocorticoid axis is associated with the incidence of a variety of diseases and illnesses (Chrousos and Gold, 1996). For exle, the opportunity to control an aversive stressor in rats influences the extent and duration of release of stress hormones by the pituitar y-adrenal system (Dantzer, 1989). Experimental studies with animals have shown that stress-induced increases of corticosteroid release are associated with the suppression of immune system activity (Cox and Mackay, 1982). In human beings, these same psychoendocrine mechanisms are implicated in the growth of some tumours such as breast cancer (Stoll, 1988). It may be speculated therefore that between prolonged exposure to psychosocial stressors and development of cancer there exist links which may depend upon neural and neuroendocrine mechanisms and their influence upon immunocompetence (Ben Nation et al., 1991; Cella and Holland, 1988). The human immune system exists to protect the body against infection and diseases. Protection against harmful bacteria and viruses is provided by barriers including, for exle, the skin and various mucous membranes of the mouth and nose as well as by active immunological processes including secretion of chemicals that can detect and inactivate pathogens, and activation of antibodies to give specific resistance to particular diseases. The immune system is continuously active but its effectiveness is sensitive to psychological influences including, for exle, the effects of psychosocial stressors (Koolhaas and Bohus, 1989). The relationship between psychological factors and the function of the immune system has been brought into prominence recently by the research upon Acquired Immune Deficiency Syndrome (AIDS), which shows 30 Downloaded by [Saudi Digital Library] at 09:02 10 October 2017 P S Y C H O P H Y S I O L O G Y, H E A LT H A N D I L L N E S S that the immunosuppressive effect of the Human Immunodeficiency Virus (HIV) is influenced by co-factors including experienced or perceived stress (see Chapter 10). Similarly, there is strong evidence that psychoimmunological influences are involved in the development and progression of cancers such as breast cancer (Cox, 1988; Stoll, 1988). There are indications too that recurrent infections with the genital herpes virus are related to changes in immune system function and those changes are themselves associated with experienced life stresses (Kemeny et al., 1989). Though much more research is needed into the precise mechanisms involved, it is plausible that the competence of the immune system for resisting infection and disease is influenced by psychological processes and states such as stress, depression, major life events such as bereavement and even minor daily hassles such as your car breaking down (Evans, Chapter 3, discusses further the significance of psychoneuroimmunology and health). Recording psychophysiological responses Psychophysiology is concerned with the influence of psychological processes or changes in behaviour upon physiological responses. It has played a significant role in the development of health psychology. Its methods depend upon measuring responses during ongoing behaviours in the performance of challenging tasks such as solving problems, learning, and so on. The techniques used to collect physiological data during these and other behaviours are often, though not always, non-invasive. Psychophysiological data are correlates of behaviour and can be used to index psychological processes such as attention, fear or stress. However, the data can be used more productively to identify the processes linking physiology and behaviour (Obrist, 1981; Phillips, 1987). Only if the data are used in this way does psychophysiology as a discipline have significance for health psychology. The psychobiological approach demands that investigators move beyond simple assertions of the type, for exle, that ‘psychosocial stress causes hypertension’ to true explanations that identify the processes involved in translating the impact of exposure to psychosocial stressors to disease states such as hypertension. This is more demanding, since it involves much more than simply identifying psychophysiological correlates of hypertension but is all the more rewarding when successful, as the elegant studies of Obrist (1981) have clearly demonstrated. Psychophysiological recording techniques have been developed that allow quantification of physiological responses of many different kinds including central ner vous system activity (individual ner ve responses, the electroencephalogram, or EEG), autonomic system activity (for exle, heart rate), endocrine responses such as the blood levels of circulating stress hormones, and indices of immune system function such as level of immunoglobulin in saliva. Each of these clearly requires specialised recording techniques whose description is beyond the scope of this discussion. Fortunately there are many good introductory texts that give an outline of the techniques involved in the measurement of these and other psychophysiological responses (Andreassi, 1980; Hassett, 1978) as well as comprehensive volumes that should 31 INTRODUCTION be consulted by anyone wishing to make use of these techniques (Coles et al., 1986; Martin and Venables, 1980). Some basic principles of recording are outlined below. Recording bioelectric responses Downloaded by [Saudi Digital Library] at 09:02 10 October 2017 Though the particular techniques used vary for different response systems, certain general features are common to all. These are illustrated in Figure 2.2 below. The measurement of bioelectric signals can depend upon direct recording, indirect recording, or the recording of transduced bioelectric signals. The differences concern the origins of the signals to be measured. Direct bioelectric signals originate in living tissues as a result of metabolic activity, and suitable electrodes placed on or near to those tissues detect those signals as electrical potentials. Good exles of this type of signal include the electroencephalogram which arises from cortical tissues, the electrocardiogram recorded from the heart, and the electromyogram recorded from skeletal muscle fibres. Indirect signals are recorded indirectly from tissues by, for exle, measuring the resistance offered by the skin to passage of a mild electric current presented via attached electrodes (skin resistance). Other signals are physical and non-electrical in origin, for exle, pressure or temperature, and special devices called transducers must be used to convert the physical signal into an electrical equivalent before they are recorded. Once detected via electrodes or transducers the electrical signals must generally be lified, since their magnitudes are small, many in the range of millivolts but some such as EEG measures in the microvolt range. In addition to simple lification there may be further processing of the signals using electronic devices such as filters, integrators and rectifiers to isolate further the signal and to eliminate artefacts that can arise from the recording techniques. Figure 2.2 Generalised features of a psychophysiological recording and measurement system 32 Downloaded by [Saudi Digital Library] at 09:02 10 October 2017 P S Y C H O P H Y S I O L O G Y, H E A LT H A N D I L L N E S S Once processed, the signal is then available for display which may be in real time using an instrument called the oscilloscope, or as a permanent written record on a paper chart by use of the device called the polygraph (literally ‘multiple writer’) which allows several response recordings to be displayed simultaneousl…
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