The role of timing in testing nonverbal IQ in children with ASD.

15 School-aged high functioning children on the autistic spectrum were compared with a neurotypical cohort on the WISC-III and the KABC-II, to determine the impact of the relatively more strict timing criteria of the former test on the evaluation of nonverbal intelligence. Significant group effects, showing lower performance by the ASD group were found for three of the five sub-tests for the WISC but not for the KABC, peaks and troughs were more evident for the WISC, and the evaluation of intellectual level was also markedly lower for ASD children on the WISC-III as opposed to the KABC-II. The results are discussed in terms of how speed of processing can impact on how children with ASD are 'matched' against neurotypical samples.

Partial occlusion depiction and its relationship with field independence in children with ASD.

We report a study of the depiction of partial occlusion and its relationship with field independence (FI) in children with ASD. Nineteen ASD children and 29 TD children (5;6-10;0) attempted to copy two 3D occluded scenes, and also selected the 'best' depiction of these scenes in drawings by others. ASD children were not significantly different from controls on FI but were significantly delayed in partial occlusion drawing and selection, independently of chronological age (CA), nonverbal mental age (NVMA) and FI.

Is it a bird? Is it a plane? category use in problem-solving in children with autism spectrum disorders.

Fourteen children with autism spectrum disorders (ASD) and fourteen age-matched typically-developing (TD) controls were tested on an adapted version of the Twenty Questions Task (Mosher and Hornsby in Studies in cognitive growth. Wiley, New York, pp 86-102, 1966) to examine effects of content, executive and verbal IQ factors on category use in problem-solving (age range 8-17). Across conditions participants with ASD asked questions that focussed on smaller categories than controls.

Free classification as a window on executive functioning in autism spectrum disorders.

Spontaneous classification was assessed using a free serial search task in 18 school-aged children at the high functioning end of the autistic spectrum and compared with results from age-matched typically developing controls. The task required participants to touch shapes in an exhaustive non-repetitive sequence. The positions of the items varied randomly between touches.

Size sequencing as a window on executive control in children with autism and Asperger's syndrome.

A study is reported in which size sequencing on a touch screen is used as a measure of executive control in 20 high-functioning children with Autistic Spectrum Disorders (ASD). The data show a significant and age-independent effect of the length of sequence that can be executed without errors by these children, in comparison with a chronologically age-matched group of children with normal development. Error data and reaction times are analysed and are interpreted as revealing a constraint on the prospective component of working memory in children on the autistic spectrum even when there is no change in goal or perceptual set.