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Background Previous research with earlier versions of the WISC and WAIS has demonstrated that when administered to people who have intellectual disabilities, the WAIS produced higher IQ scores than the WISC. The aim of this study was to examine whether these differences still exist. A comparison of the Wechsler Adult Intelligence Scale – Third Edition (WAIS-III) with the Wechsler Intelligence Scale for Children – Fourth Edition (WISC-IV) was conducted with individuals who were 16 years old and receiving special education. Materials and Methods All participants completed the WAIS-III (UK) and WISC-IV (UK). The order of administration was counterbalanced; the mean Full Scale IQ and Index scores on the WAIS-III and WISC-IV were compared. Results The WAIS-III mean Full Scale IQ was 11.82 points higher than the mean Full Scale IQ score on the WISC-IV. Significant differences were also found between the Verbal Comprehension Index, Perceptual Reasoning/Organization Index and Processing Speed Index on the WAIS-III and WISC-IV, all with the WAIS-III scoring higher. Conclusions The findings suggest that the WAIS-III produces higher scores than the WISC-IV in people with intellectual disabilities. This has implications for definitions of intellectual disability and suggests that Psychologists should be cautious when interpreting and reporting IQ scores on the WAIS-III and WISC-IV. [ABSTRACT FROM AUTHOR]

Objective It has been suggested that, as the Wechsler Adult Intelligence Scale-Third Edition (WAIS-III) and the Wechsler Intelligence Scale for Children-Third Edition (WISC-III) give a scaled score of one even if a client scores a raw score of zero, these assessments may have a hidden floor effect at low IQ levels. The study looked for indications of this in a sample of assessments that had been given for clinical and diagnostic reasons. Design The degree to which a hidden floor effect could be present was assessed by looking at the proportion of scaled scores of one in IQ bands: 50–59, 60–69 and 70 plus and by plotting the distribution of scaled scores in these bands for both the WISC-III and WAIS-III. Method Fifty WISC-III and 49 WAIS-III assessments were obtained from records and analysed. Results The distribution of scaled scores in the WAIS-III was approximately normal with very few scale scores of one, suggesting that a hidden floor effect would only be a potential problem for IQs in the 40s and 50s. The WISC-III had a skewed distribution of scaled scores with more scaled scores of one than any other scaled score. Scaled scores of one were shown in all IQ levels up to 70 plus. Conclusions There is potentially a significant floor effect on the WAIS-III at IQs in the 40s and 50s and on the WISC-III up to IQs in the 70s. There are also indications that the WISC-III has a much harder criterion for gaining a scaled score of two than the WAIS-III, resulting in it producing lower IQs. [ABSTRACT FROM AUTHOR]

Background It has often been stated that the prevalence of psychiatric disorders in people with intellectual disabilities is greater than it is in the population as a whole. Method The epidemiological studies on psychiatric disorders in people with intellectual disabilities were reviewed. Results There is evidence that the prevalence of psychiatric disorder is greater in children with intellectual disabilities, compared with children with normal IQs, that it is higher in both adults and children with severe intellectual disabilities compared with people with mild or no intellectual disability and that the rate of problematic behaviour is higher in both adults and children having intellectual disabilities, than in their non-disabled peers. Conclusions There is no sound evidence that the prevalence of psychiatric disorders in adults with mild intellectual disability is greater than in the population as a whole. [ABSTRACT FROM AUTHOR]

Although it has been suggested that about 2.5% of the population as a whole should be regarded as having a mild-to-moderate learning disability, only about 0.25% of the population is registered as having a learning disability. This paper considers why this disparity exists. It is suggested that although 2.5% of the population may be a good estimate for people with IQs less than 70, a better estimate of the proportion of the population who reach a dual criteria of having both a low IQ and social/skill defects is about 1%. It is pointed out that even if true prevalence rate of learning disability is nearer to 1% rather than 2.5%, services still only know of a small proportion of people who could be considered to have a learning disability, and there are probably a large number of people with unidentified learning disabilities. It is also noted that the term ‘learning disability’ can be very confusing as it is not clear if it refers to people who have IQs below 70, people with both intellectual and adaptive disabilities or people who have been given a learning disability label. The implications of this for services and research are discussed. [ABSTRACT FROM AUTHOR]

Comments on a paper in the 'British Journal of Learning Disabilities' about the problem of not knowing who or where the majority of people with learning disabilities are. Percentage of the population who have a learning disability; Proposals for learning disability services nationally.

Summary It is argued that challenging behaviours can be better understood if a correlational analysis (i.e. looking for correlations between the occurrence of the behaviour and other variables) is used in addition to functional analysis. A case example is provided of a man whose aggressive outbursts were negatively correlated with trips out of his unit. [ABSTRACT FROM AUTHOR]