ABSTRACT
The goal of this chapter is to familiarize the reader with approaches used to assess the intellectual abilities of persons with autism. In order to evaluate the intellectual abilities of persons with autism it is necessary for the clinician to appreciate what is known about the organization of intellectual abilities that are typically associated with the disorder and to understand how to effectively assess mental retardation because it frequently is present as a comorbid condition. Thus, it is critical that clinicians assessing such individuals have both the understanding and the capacity to evaluate across a range of developmental abilities as well as have at their disposal appropriate instruments that can be employed as part of the evaluation.Another important factor in assessing individuals with autism and related disorders is the examiner’s ability to work with behaviors that may interfere in the assessment process. It is important to evaluate whether the individual is actually taking examinations in a manner that truly allows the sampling of behaviors suggestive of intellectual processes. Successful performance on intellectual tests is probably valid. However, poor performance may or may not be reflective of intellectual ability. Failed items can be due to limited skill, an inability to comprehend instructions, poor cooperation, impulsive behavior, variable attention, or a combination of any of these performance issues. The examiner therefore needs to be experienced in evaluating how such behavioral factors might be affecting the evaluation process and make reasonable attempts to accommodate the individual’s compromised capacity to take the test.
Infantile Autism or Autistic Disorder (AD) was first described by Leo Kanner in 1943 as a severe developmental disorder that includes severe communication, social, and behavioral disturbances. Furthermore, it is now known that persons with AD suffer from atypical brain development (see Courchesne, 1997, review) as well as atypical and uneven patterns of cognitive development (Lincoln, Courchesne, Kilman, & Elmasian, 1988; Lincoln, Allen & Kil-man, 1995, review; Siegel, Minshew & Goldstein, 1996). It is likely that the atypical patterns of cognitive development reflect biologically based differences in brain functions, which are secondary to the brain abnormalities as well as the abnormalities of learning and metacognition. In 1979 Michael Rutter stated: “There is good evidence for the existence of a basic cognitive deficit in autism. This deficit generally involves impaired language, sequencing, abstraction and coding functions. It is also associated with abnormalities in language function and usage which are particularly characteristic of the autistic syndrome” (p. 261). Cognitive deficits also may underlie impaired social and emotional behavior, thus affecting the whole spectrum of functioning (Rutter 1983; Tager-Flusberg, 1999; Tager-Flusberg, Joseph, & Folstein, 2001). In contrast, the abilities of perceptual discrimination, rote memory, and visu-ospatial skills appear to be essentially intact (Lincoln et al., 1988; Lockyer & Rutter, 1970; Rumsey, 1992; Rutter & Schopler, 1988; Lincoln et al., 1995, review).Distinctive patterns of cognitive strengths and weaknesses have been observed in high-functioning autistic individuals (e.g., Allen, Lincoln, & Kaufman, 1991; Asamow, Tanguay, Bott, & Freeman, 1987; Goldstein, Beers, Siegel, & Minshew, 2001; Iverson, 1997; Lincoln et al., 1995; Lockyer & Rutter, 1970; Ventor, Lord, & Schopler, 1992). Although there is still some degree of controversy regarding the full nature of the cognitive impairments in persons with AD (Siegel, Minshew, & Goldstein, 1996), there is general consensus that nonretarded persons with AD typically have better visual-spatial ability than verbal comprehension ability (Lincoln et al., 1988, 1995; Siegel, Minshew, & Goldstein, 1996). Lincoln et al. (1988) suggested that the more intact visual-spatial ability in nonretarded persons with AD might reflect relatively intact functions related to fluid intelligence-specifically, functions related to the processing of visual information that is independent of the evaluation of contextually relevant or language-based information. However, Minshew, Goldstein, & Siegel(1997) suggest that it is the relative complexity of intellectual demands that limits the individual with AD such that they demonstrate “impairments in skilled motor, complex memory, complex language and reasoning domains (and are relatively intact with respect to) performance in the attention, simple memory, simple language and visual-spatial domains” (p. 303).However, this idea of a weak capacity to process complex information and problems does not fit with the relative efficiency of how well nonretarded persons with autism solve complex matrix reasoning tasks. On matrix reasoning tasks, the individual is required to evaluate multiple relationships or dimensions simultaneously and infer how a pattern can best be completed. On such tasks, all of the information necessary to solve the task is available to the examinee, so that previous experiences with the stimuli are not necessary to recall in order to be successful. However, on the types of verbal reasoning tasks typically employed on formal IQ tests, it is necessary to evaluate contextually relevant information and to use previous knowledge and experience to appropriately infer a correct solution.The errors in solving verbal comprehension tasks made by individuals with autism often reflect their ability to attend to only one of the dimensions of the problem posed to them and their failure to evaluate the broader context. For example, a young man came to a social
