If you ask any counsellor or psychotherapist who works with people who do not have intellectual disabilities what influences the behaviour and decisions of the people they work with, they will probably mention a number of factors including the person’s relationships with other people, their personality, upbringing and their family history. It is unlikely that they would say ‘cognitive functioning’ or ‘IQ’. And yet there is a widespread assumption that the behaviours of people with an intellectual disability are primarily the result of cognitive deficits. Furthermore, the dominance of behaviourism and behaviourally derived approaches to working with people with intellectual disabilities has tended to emphasise a ‘one.size fits all’ approach, the theory being that people’s behaviour is most strongly influenced by external environmental contingencies and reinforcement, rather then anything internal to the person. Yet in the general population individual differences are seen as key issues in matters such as career choice, job satisfaction and relationship formation.
In the past four years there has been a small but growing body of research into the area of individual differences in people with intellectual disabilities. This is leading to some interesting developments in the area, including the assessment and prediction of compatibility of housemates with intellectual disabilities. For instance, Wiltz and Reiss (2003) found that they were able to distinguish between compatible and incompatible housemate pairs on the basis of their scores on a measure of motivation (Reiss Profile).
Research into the relationship between personality traits and particular psychiatric and behavioural disorders has also highlighted the relevance of personality and motivational assessment. Lecavalier and Tassé (2002) identified a group of people with intellectual disabilities who had psychiatric disorders such as anxiety and mood disorders or behaviour disorders such as self-injurious behaviour, using a high score on the Reiss Screen for Maladaptive Behavior. Secondly, they identified a similar control group who had only an intellectual disability. They compared the two groups using a measure of personality and motivation and found significant differences in the two groups on eight of the fifteen subscales.
One of the most useful possible areas of development is in the analysis of motivation of challenging behaviours. Traditionally used methods such as the Motivational Assessment Scale have been hampered by difficulties such as low inter.rater reliability (different staff/family members not being able to agree on the motivation for the behaviour). It also allowed for only four possible interpretations as to the functional motivation of the challenging behaviour. The development of the Reiss Profile offers a more finely.tuned and individualised analysis of the motives of the individual who is being assessed that may be informative in interpreting the causes of the challenging behaviour. Though this work is still in its early stages and requires further validation and reliability analysis (and, in particular, the use of longitudinal studies), it does suggest a new and interesting development in work with people with intellectual disabilities.
The work on individual differences in motivation may help yield useful and practical insights in how to effectively reduce the incidence of challenging behaviour and increase the degree to which people with intellectual disabilities can lead full, integrated and rewarding lives.