A Guide to Psychological Understanding of People with Learning Disabilities

Eight Domains and Three Stories

Jenny Webb

• Publisher: Routledge
• Year: 2013
• Print ISBN: 9780415601153
• eBook ISBN: 9781135089184
• Topic: Psychology
• Subtopic: Clinical Psychology
• Index: Psychology

Who are the people we describe as having learning or intellectual disability? Many clinical psychologists working in a mental health setting are now encountering people with learning disabilities, in some cases for the first time. This book provides the background information and understanding required to provide a basis for a truly inclusive and effective service for people with learning disability.

In A Guide to Psychological Understanding of People with Learning Disabilities, Jenny Webb argues that we need a new, clinically-based definition of learning disability and an approach which integrates scientific rigour with humanistic concern for this group of people, who are so often vulnerable to misunderstanding and marginalisation. Psychological approaches need to be grounded in an understanding of historical, theoretical and ethical influences as well as a body of knowledge from other disciplines. The Eight Domains is a simple but holistic method for information gathering, while The Three Stories is an integrative model of formulation for use in relation for those people whose needs do not fit neatly into any one theory. Divided into three sections, the book explores:

Understanding the context

Understanding the person: eight domains

Making sense: three stories.

This book provides an invaluable guide for trainee clinical psychologists and their supervisors and tutors, working with adults with learning disability. It will also be valuable for clinical psychologists working in mainstream settings who may now be receiving referrals for people with learning disability and want to update their skills.

Part I

Understanding the context

1 Defining the construct of learning disability

As I begin this book, I face a quandary. How am I to write about this subject without using some of the terminology that is the subject of study? After long consideration, I have decided to adopt the term ‘learning disability’ when referring to contemporary usage. This chapter explains this decision, and what I mean by the term ‘learning disability’.

The history of learning disability is partly the history of changes in terminology. In the United Kingdom the term ‘idiocy’ was replaced by the terms ‘mental deficiency’, ‘mental handicap’ and latterly ‘learning disability’. ‘Mental impairment’ is used in some legislation, and ‘special needs’ is the term in common usage to describe children with developmental disabilities and others. Members of the self-advocacy group People First have expressed a preference for the term ‘learning difficulties’. In America the term ‘feebleminded’ was replaced by that of ‘mentally retarded’, and ‘intellectual disability’ is the term now generally adopted by the international scientific community.

Such changes in terminology and classificatory systems have to some extent been driven by the ongoing attempt to escape the stigma attached to earlier terminology, but they also reflect changes in the concept of learning disability itself. In the positivist tradition such changes would be viewed as attempts to get ever closer to the ‘true’ definition of learning disability as a medical diagnosis. Alternatively, the change in language may be seen as representing changes in social structure, power relationships, values and in the abilities needed for survival in specific cultures.

Current definitions are given by the diagnostic manuals of the WHO and the APA, as well as national bodies such as the AAIDD. The ICD-I0 and DSMIV are currently being revised. Most current definitions refer to three criteria, involving (i) early age of onset, (ii) cognitive impairment (represented by IQ score) and (iii) functional disability. For example, the ICD-10 identifies four degrees of severity of mental retardation, which it defines as an:

arrested or incomplete development of the mind, which is especially characterized by impairment of skills manifested during the developmental period, skills which contribute to the overall level of intelligence, ie cognitive, language, motor, and social abilities.

(WHO, 1994: F70–79)

A radical challenge to the general diagnostic manuals came from the AAMR that, in 1992, influenced by the social model of disability, published a revised diagnostic manual. While it broadly accepted the usual three criteria given for classification of mental retardation and the IQ < 70 cut-off, it also stated, in a memorable phrase, that mental retardation ‘is not something you “have” like blue eyes or a bad heart’ (AAMR, 1992: 9). The importance of social environment was acknowledged in the Levels of Support model, referring to the frequency and intensity of support people need in particular social contexts. The four levels of support were described as: Limited, Intermittent, Extensive and Pervasive, and were not associated with IQ scores.

The White Paper Valuing People also referred to a four-part classification, though without defining the categories (DH, 2001a). Also in 2001, the BPS produced its own guide to definitions. This acknowledged the fact that learning disability is a social construct but nevertheless went on to provide a definition of the concept close to that of the diagnostic manuals. This was on the grounds that it is enshrined in our social and legal systems and so affects people's legal and civil rights. However it stressed the importance of flexibility and clinical judgement in diagnosis. It stated that IQ score should only be interpreted in the context of a holistic assessment, covering ‘biological, psychological and interactional factors, within the broader social/cultural and environmental context’ (BPS, 2001: 2). These guidelines are also currently being revised.

The BPS suggested collapsing the four-level classification into a two-level classification, since it found no reliable or valid psychometric instruments to make the distinction between the Moderate, Severe and Profound categories. The BPS also introduced its own nomenclature. Thus, ‘mild mental retardation’ became ‘Significant Impairment of Intellectual Functioning’, and the other three categories (less than IQ 55) (confusingly) became ‘Severe Impairment of Intellectual Functioning’. This means that ‘Severe’ is defined at IQ 35 internationally, whilst being set at IQ 50–55 in the UK, though only if this is associated with a need for an Extensive Level of Support.

In the UK, the psychiatric and psychological systems co-exist, with implications for individual entitlement to support, governmental planning and legal judgements. The construct of learning disability is thus mired in confusion. This is partly because its scientific foundations are shaky.

Theoretical issues in the definition of learning disability

The vignette on p. 9 illustrates the gulf that exists between lay and scientific concepts. In contrast to lay concepts, the criteria for acceptance of hypothetical constructs in science are rigorous. In everyday life, we may all vary in the way we define a construct such as ‘intelligence’, and yet we will probably be able to engage in a dialogue without too much misunderstanding, since in such a conversation meanings are constantly checked and refined. Scientific investigation, on the other hand, requires a foundation of shared meaning. This foundation

The trainee and the tutor

The tutor's small stature and delicate appearance belie the sharpness of her intellect and the force of her personality. Week after week the clinical psychology trainees are forced to question all the assumptions with which they entered training. In particular they are taught the limitations of the medical model and the need for psychologists to think through their ideas from first principles.

The tutor packs up her files and leaves the room after a particularly taxing seminar. The trainees turn to look at each other. Finally, one breaks the silence:

‘Well!’ she proclaims. ‘Mental illness might not exist in this college, but it bloody well exists in the day hospital where I'm working!’

is comprised of two key pillars: the theoretical status of the hypothetical construct and its relationship to the theoretical network of which it forms a part.

Hypothetical constructs

Scientific theories contain observables (directly involving sense data) and unobservables. An unobservable is an ‘abstract concept inferred from overt behaviour or from verbal reports of behaviour and experience’ (Boyle, 2002: 2). MacCorquodale and Meehl (1948) suggest that unobservables may be one of two types: ‘intervening variables’ and ‘hypothetical constructs’. ‘Intellectual disability’ falls into the latter category. It is an abstraction, not reducible to a statement about behavioural correlations.

Ontological status

Do hypothetical constructs ‘really’ exist? And, if so, in what sense? The positivist view is that they do, and that scientific endeavour is directed towards helping us uncover and understand them:

Since hypothetical constructs assert the existence of entities and the occurrence of events not reducible to the observable, it would seem to some of us that it is the business of a hypothetical construct to be ‘true’…. The ultimate ‘reality’ of the world in general is not the issue here; the point is merely that the reality of hypothetical constructs like the atom… is not essentially different from that attributed to stones, chairs, other people and the like.

(MacCorquodale and Meehl, 1948: 104–105)

According to Boyle, this statement ignores the distinction between those hypothetical constructs that are assumed to ‘really exist’, and for which scientists may search (e.g. an atom), and those that will always be abstractions, as is the case with both learning disability and intelligence. Nevertheless, both in service delivery systems and in academic research, the view that these constructs do have a ‘real’ existence prevails.

Validity

The theoretical status of a hypothetical construct is often described in terms of its validity, i.e. the extent to which it measures what it is claimed to measure. Various types of validity have been identified, including content, concurrent, predictive, construct, ecological, social, convergent and discriminant (Chaytor and Schmitter-Edgecombe, 2003; Cronbach and Meehl, 1955; Wechsler et al, 2008).

Correspondence rules

A hypothetical construct forms part of a theoretical network that relates observables to each other and to unobservables. This network is described in terms of correspondence rules that link observable events and unobservable constructs. They specify ‘what must be observed before the concept can be inferred and may specify quantitatively the relationship between variation in what is observed and variation in the inferred construct’ (Boyle, 2002: 4). The correspondence rules also provide the means for examining the predictions from a construct and may evolve as more observations are made over time.

Medicine

Medicine is a branch of science, within which the construct of ‘disease’ is usually seen as an entity with a discrete and unchanging identity. The correspondence rules for inference of the disease or syndrome in question constitute its diagnostic criteria, and have predictive power.

Correspondence rules/diagnostic criteria involve an observed cluster of symptoms and signs. A symptom is a phenomenon that is subjectively experienced by the person, whereas a sign is an independently measurable event that is reliably associated with a cluster of symptoms, and theoretically linked with it as an antecedent (e.g. a blood test result) as well as being linked theoretically to the construct. Observations made over time may result in the evolution of diagnostic criteria. From the positivist point of view, this is the means by which diagnosticians may come closer to the ‘true’ definition of the disease. On the other hand, Boyle (2002) suggests that disease names are simply concepts that are inferred from clusters of signs and symptoms. When correspondence rules/signs and symptoms change over time, this does not change the nature of the disease, but the theoretical network in which the construct is embedded.

Pilgrim (2011) criticises the scientific integrity of psychiatric diagnoses on four grounds: their lack of predictive validity (e.g. regarding prognosis); their lack of concept validity (e.g. overlapping categories); their lack of treatment specificity; and their definition in terms of symptoms rather than ‘hard biological signs’.

Learning disability as a medical diagnosis and hypothetical construct

The inclusion of learning disability in the diagnostic manuals implies that it is not merely a summary description but a scientifically respectable medical hypothetical construct. Whether it merits this status depends on whether it meets the necessary and sufficient conditions for such a construct.

The diagnostic criteria for learning disability have been, and continue to be, subject to regular revisions, made on the basis of discussion among respected academics and practitioners. We would expect that such revisions would be made on the basis of empirical evidence or theoretical developments but instead the process can seem arbitrary.

The current proposal for revision of the DSM is that a change be made from a descriptive to a more aetiological focus (Andrews et al, 2009a). But suggested changes have been criticised on the grounds both of their lack of validity and of their overly rigid reliance on test results (AAIDD, 2009; Wittchen et al, 2009). The category of learning disability will be subsumed under a broad category termed Neurodevelopmental Disorders. The evidence for the existence of this category seems to have been taken mainly from studies of people with autistic spectrum disorder, which constitute nearly half of the references given. Many of the other references relate to ADHD (attention deficit hyperactivity disorder), dyslexia and stuttering! Notwithstanding the fact that ‘genomic screens have not identified “neurodevelopmental” genes common to all these disorders… it is presumed that disorders within clusters will co-aggregate, do support some common neurodevelopmental genetic risk’ (Andrews et al, 2009b: 2015).This analysis leads Andrews et al to come to the astounding conclusion that ‘Autism and Asperger's disorders fall at the “severe” end of the genetic spectrum whereas disorders such as mild mental retardation occur at the “mild” end of the spectrum’ (Andrews et al, 2009b: 2016).

Learning disability and intelligence

The construct of learning disability piggy-backs on the further construct of intelligence, since it is intelligence testing that is used to assess learning disability. This brings us to the issue of the validity and reliability of intelligence tests and of the cut-off point used to define learning disability. This complex issue is one that I can only skate over here.

Validity

The cut-off for diagnosis of learning disability is usually given as two standard deviations below the mean, which equates to IQ 70, covering 2.28 per cent of the population. This is an arbitrary figure, made more problematic by the ‘Flynn effect’ that has resulted in the periodic r...

Table of contents

• Cover Page
• Half Title page
• Title Page
• Copyright Page
• Dedication
• Contents
• Figures
• Acknowledgements
• Abbreviations
• Introduction
• Part I Understanding the context
• Part II Understanding the person Eight Domains
• Part III Making sense Three Stories
• Appendix 1 Initial assessment — prompt sheet
• Appendix 2 My Life — initial assessment sheet for client*
• Appendix 3 Cognitive assessment
• Bibliography
• Index