Journal of Autism and Developmental Disorders, Vol. 31, No. 1, 2001 Movement Preparation in High-Functioning Autism and Asperger Disorder: A Serial Choice Reaction Time Task Involving Motor Reprogramming Nicole J. Rinehart, 1,3 John L. Bradshaw, 1 Avril V. Brereton, 2 and Bruce J. Tonge 2 Autism and Asperger disorder have long been associated with movement abnormalities, al- though the neurobehavioural details of these abnormalities remain poorly defined. Clumsiness has traditionally been associated with Asperger disorder but not autism, although this is con- troversial. Others have suggested that both groups demonstrate a similar global motor delay. In this study we aimed to determine whether movement preparation or movement execution was atypical in these disorders and to describe any differences between autism and Asperger disorder. A simple motor reprogramming task was employed. The results indicated that in- dividuals with autism and Asperger disorder have atypical movement preparation with an intact ability to execute movement. An atypical deficit in motor preparation was found in Asperger disorder, whereas movement preparation was characterized by a “lack of anticipation” in autism. The differences in movement preparation profiles in these disorders were suggested to reflect differential involvement of the fronto-striatal region, in particular the supplementary motor area and anterior cingulate. KEY WORDS: Asperger disorder; autism; movement execution; movement preparation. INTRODUCTION Autism and Asperger disorders are characterized by anomalies in motor, social, and communicative functioning. Asperger disorder is distinguished from autism by the absence of clinically significant delays in language (American Psychiatric Association [APA], 1994). The clinical profile of autism and Asperger dis- order contains an intriguing mixture of psychiatric and neurological symptoms: for example, movement ab- normalities (i.e., stereotyped behaviors, hand flapping, toe walking, whole-body movements), verbal and non- verbal communication deficits, ritualistic/compulsive behaviour, and disturbances in reciprocal social inter- action (APA, 1994). It is a much debated issue whether autism and Asperger disorder are variants of a single disorder or whether each has a distinct neurobiology and etiology (Pomeroy, 1998). General cognitive ex- amination has revealed that Asperger disorder may be associated with a higher overall IQ than high-func- tioning autism (Manijiviona & Prior, 1999). Compar- isons of social ability in these disorder groups using theory-of-mind tasks have provided conflicting results (see Dahlgren & Trillingsgaard, 1996; Jolliffe & Baron- Cohen, 1999). Recent studies have revealed that autism and Asperger disorder may have different psychiatric and neurological manifestations. For example, Tonge, Brereton, Gray, and Einfield (1999) found higher lev- els of psychopathology reported in individuals with Asperger disorder than for individuals with autism. Conversely, Rinehart, Bradshaw, Moss, Brereton, and 79 0162-3257/01/0200-0079$19.50/0 © 2001 Plenum Publishing Corporation 1 Neuropsychology Research Unit, Monash University, Clayton, Victoria, Australia, 3168. 2 Monash University Centre for Developmental Psychiatry, Monash Medical Centre, 246 Clayton Road, Clayton, Victoria, Australia, 3168. 3 Address all correspondence to Nicole J. Rinehart, Neuropsycho- logy Research Unit, Department of Psychology, Monash Univer- sity, Clayton, Victoria, Australia, 3168. e-mail: Nicole.Rine- hart@sci.monash.edu.au