fBy Professor Alan Hudson FAPS, Head, School of Health Sciences, RMIT University and
Gary Radler MAPS, Gary Radler Pty Ltd

A variety of terms have been used to describe the condition of people who have a low level of cognitive functioning and associated deficits in adaptive behaviour (skills of daily living). A sample of these are: developmental disability, intellectual disability, mental deficiency, mental handicap, mental retardation, and learning disability. In England the term 'learning disability' is used, while in the United States the term 'mental retardation' is the prevalent term. In Australia the most commonly used term is 'intellectual disability'. This term is used in legislation in some States; for example, the Intellectually Disabled Persons' Services Act (1986) is a key piece of legislation in Victoria. It is also the term used in the title of peak organisations in Australia; The Australasian Society for the Study of Intellectual Disability (ASSID) is the relevant scientific body. The National Council on Intellectual Disability (NCID) is the relevant co-ordinating body for service and advocacy bodies. Because of its widespread local usage, the term 'intellectual disability' has been used in this article.

The manner in which services have been provided for pefople with intellectual disabilities has changed considerably during recorded history. Scheerenberger (1982) provides a detailed description of these developments. In recent decades there has been a major change in the field with regard to views about the general nature of services that should be made available to people with intellectual disabilities. Gone is the view that intellectual disability is essentially a medical problem and hence requires medical care. This has been replaced by the view that intellectual disability is an educational/developmental problem and the core needs are for advocacy, flexible and individualised support, and the provision of learning opportunities. Inherent in this change of view is the realisation that people with an intellectual disability are capable of learning many skills when the opportunities are provided.

Influential in the change of thinking that has occurred have been the normalisation theories of Nirje (1985) and Wolfensberger (1972, 1983). While there are some differences between the detailed views of Nirje and Wolfensberger, they both have argued for models of service provision allowing people with a disability to lead as normal a life as possible. It is important to note here that by normalisation they did not mean making intellectually disabled people average or normal, but rather to provide them as much as possible with the opportunities and experiences that non-disabled people have access to.

A major corollary of the implementation of normalisation principles has been a change in the accommodation options available to people with a disability. Congregate care in large, institutional, hospital-like settings, a legacy of the outmoded medical model, was replaced by a preference for smaller size options, such as shared flats or living in groups of four or five in houses in the community, called community residential units (CRUs). In the last half-decade the most innovative service providers are now providing individualised supports that enable people with a disability to live in their own homes with people they choose.

It is important to note that relocation from large institutions to smaller scale options, often referred to as de-institutionalisation, does not mean less resources are required to provide the support services for the people involved. Unfortunately, some attempts at de-institutionalisation have not succeeded due to a failure to adequately provide necessary support services in the community. In contrast, there are many examples, both in Australia and overseas, in which people with intellectual disabilities have been successfully relocated into the community (for example, Radler, Laurie & Gavidia-Payne, 1999; Radler, 2004). The person-centred planning movement (Kincaid, 1996; O'Brien, Mount, & O'Brien, 1991) has articulated values and provided tools for planning with individuals with an intellectual disability so that they can be fully included in the life of the community.

Many psychologists work with people who have an intellectual disability. For some psychologists it will be the prime focus of their job. This will apply to the psychologists who work for the various State government disability services. For other psychologists it will be an incidental part of their job. This would apply, for example, to psychologists who work for a State government department of education, in hospital out-patient clinics, or in private practice. It is not unreasonable to suggest that because of the use of generic services by people with intellectual disabilities, all psychologists need to be professionally prepared to provide them with appropriate support.

The nature of psychological work in the field of intellectual disability will vary considerably, but three major areas are the assessment of individuals, the planning and provision of interventions to address challenging behaviour, and the evaluation of services provided to disabled people. 

Assessment of people with intellectual disability

Psychologists working in the field of intellectual disability often find themselves in the position of assessing people. The purpose of the assessment can vary, but is likely to be one of the following:

  • To determine if the person does have an intellectual disability. This in effect is a determination of whether the person is eligible for services made available to people with intellectual disabilities.
  • To determine the person's current skill level.
  • To determine the person's level of support need.

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Assessment for intellectual disability

The definition of intellectual disability typically involves the existence of a significantly sub-average level of general intelligence, deficits in adaptive behaviour, and a manifestation of both of these in the developmental years, which is usually taken as being from birth to 18 years of age. To determine if an individual has an intellectual disability, therefore, the psychologist is usually involved in assessing both intelligence and adaptive behaviour. A difficulty that arises here is that the precise criteria for determining low levels of intelligence and adaptive behaviour have varied over time and from place to place. By way of example, the American Association on Mental Retardation, a peak body in the field, has continuously changed the criterion for the intelligence level. It has variously been specified in terms of standard deviations below the mean (either 1 or 2), or in terms of a particular score (either 70 or 75) (Macmillan, Gresham, & Siperstein, 1993). Similarly, the criterion for required low level of adaptive behaviour has changed. Psychologists working in the field need to acquaint themselves with what is required by the local statutory authorities.

The assessment of intelligence and adaptive behaviour is usually done by using standardised tests. Hudson and Jauernig (1985), however, have highlighted some technical difficulties in using these tests to determine intellectual disability.

It is important for several reasons that psychologists be well trained in conducting intellectual disability assessments. The first and most critical is that the decision based on the assessment is extremely important for the individual concerned. It is only if the individual is assessed as having an intellectual disability that a range of services will be available. Second, from a general perspective, the total services available to people with a disability are unfortunately less than most would like, and hence it is important that these services get to the people who need them most. Finally, because access to services is important, a psychologist's decision might be challenged and have to be defended. This mostly occurs through the operation of standard statutory review mechanisms, but it may also be challenged in a court of law.

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Assessment of skill level

In general terms, a critical need of people with an intellectual disability is assistance to learn new skills. Assessment of current skill level is an important component of the development of appropriate programs for this purpose. In contrast to assessing individuals for the presence of intellectual disability where norm referenced tests are used, assessments for planning educational programs require the use of criterion referenced tests. Devices such as the Vineland Scales of Adaptive Behaviour (Sparrow, Balla & Cicchetti, 1984) and the Scales of Independent Behaviour - Revised (Bruininks, Woodcock, Weatherman & Hill, 1996) can be used for criterion referenced as well as norm referenced assessment, but there are also specific criterion referenced devices available. The Checklist of Adaptive Living Skills (CALS) by Morreau and Bruininks (1991) assesses an individual's performance on 800 specific skills organised into four domains: personal living skills, home living skills, community living skills, and employment skills.

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Assessment of support need

One development in the field of intellectual disability has been to replace the traditional classification based on level of disability (such as, mild, moderate, severe, or profound) with a classification based on level of support need (such as, intermittent, limited, extensive, or pervasive) (American Association on Mental Retardation, 2002). The criterion for classification in the old system was level of intelligence. In the new system there are multiple criteria, but things such as skill level and the existence of difficult or challenging behaviour are prominent. Assessment in terms of level of support need has become more important as governments move towards what is called 'unit based funding'. The use of this approach means that the amount of money made available to an agency providing service to an individual depends upon an assessment of the support need of that individual. A useful instrument for assessing support need is the Inventory for Client and Agency Planning (ICAP) developed by Bruininks, Hill, Weatherman, and Woodcock (1986).

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Interventions for challenging behaviour

Behaviour problems among people with intellectual disabilities can include behaving aggressively towards others; self-injurious behaviours like biting, hitting, eye-poking, and eating inedibles; behaviours that lead to property damage; inappropriate social and sexual behaviours like hugging strangers or public masturbation; self-stimulatory behaviours like hand mouthing and excessive rocking; extreme withdrawal; and non compliance.

Such behaviour problems are often referred to as 'challenging behaviours'. This term was originated by advocates of people with disabilities who argued that terms like 'behaviour disorder', 'disturbed behaviour', 'inappropriate behaviour' and 'behaviour problem' wrongly attribute ownership and blame to the person, as if they carried the behaviour around as symptoms of their disability. Instead, the advocates argued, their behaviour was a very understandable response to often unstimulating, inflexible, de-humanising and unresponsive services. Their behaviours in fact represented challenges to service systems to improve and to become more responsive.

People with an intellectual disability who demonstrate challenging behaviours are often referred to psychologists working in intellectual disability services. Behavioural intervention approaches based on the theoretical framework of applied behaviour analysis have proved particularly useful in addressing challenging behaviours in this population. This most often involves working with and through the significant others in the person's life, like family members, teachers, and accommodation support staff. These approaches are collectively referred to as 'Positive Behaviour Support' (Carr et al., 2002).

The application of these approaches sees the psychologist involved working collaboratively with the significant others in the person's life in assessing the individual, planning an intervention based on the assessment findings, and often training and supporting people like parents, teachers, accommodation support staff and others in the application of the intervention. As well as these tasks, psychologists also sometimes monitor how well the intervention is being implemented and its results, assist in the review of the intervention, and provide ongoing support to those implementing the intervention. Psychologists working in intellectual disability services therefore require well-developed knowledge and skills in working through all these stages of the behaviour intervention process.

With regard to the selection of an intervention procedure, a strong debate concerning whether aversive consequences, such as water sprays, are ever necessary to successfully reduce challenging behaviours has existed in the field (Jacobson, Foxx, & Mulick, 2005; Repp & Singh, 1990). However, it is very rare for aversive procedures to be used in contemporary society and often they are precluded or severely limited by statutory regulations. 

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Program evaluation

Many psychologists in the field of intellectual disability are becoming involved in evaluation activities. Psychologists should as a matter of course routinely evaluate the individual clinical interventions they initiate. Such evaluation is generic to the scientist practitioner model used in most professional training courses. Formal program evaluation is evaluation of a much broader scope and can be thought of as two types, the systematic evaluation of established service programs, and the evaluation of specific practices which permeate the field and can be loosely described as new or controversial therapies.

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Service programs

Evaluations of service programs are carried out primarily to assist in decision making about the program. The usual focus is on how the program can be improved, but occasionally it may be to decide if the program should continue. Governments or others who provide funding are usually the people most interested in the outcomes of the evaluation, and the evaluations may contain a cost-benefit analysis component.

The evaluation of service programs has its roots early in last century in the education field in which the critical questions asked were about the effectiveness of teaching programs. Since that time the practice has spread throughout the human service sector. A very substantial amount of literature is now available, and there are some excellent general texts for psychologists new to the area; for example, Atkisson, Hargreaves, Horowitz, and Soresen (1977), and Stufflebeam, Madeus, and Kellaghan, (2000). A text on program evaluation that has been specifically written for the intellectual disability field is that by Schalock and Thornton (2002).

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New and controversial therapies

From time to time new approaches to treatment develop in the intellectual disability field. Unfortunately, these new approaches can be widely adopted before any evaluation of them is conducted. Under these circumstances psychologists can find themselves placed in the difficult situation of questioning and evaluating the efficacy of something that people in the field have a strong commitment to. These evaluation tasks become even more difficult when the research data fails to support the new approach, and information about this must be disseminated to an audience that is reluctant to accept the evidence. Examples of such new and controversial therapies are Sensory Integration Therapy and Facilitated Communication Training. An excellent review of the evidence (or lack of it) for these approaches is provided by Jacobson, Foxx, and Mulick (2005).

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Concluding comments

In this article it has been suggested that the nature of psychological work in the field of intellectual disability will include to a large extent the assessment of individual persons, the planning and provisions of interventions for challenging behaviour, and the evaluation of services for people with a disability. However, it also needs to be stressed that people with disabilities will essentially have the same general needs as people without disabilities, and hence psychologists must be prepared to provide more general psychological services to this important group in our community. This applies of course not just to psychologists employed in the disability sector, but also to those who work in the community at large.

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