Inhibition of return in young people with autism and Asperger ' s

A D D R E S S Correspondence should be addressed to: N I C O L E J. R I N E H A RT , Centre for Developmental Psychiatry and Psychology, School of Psychology, Psychiatry and Psychological Medicine, Monash University, Building 1, 270 Ferntree Gully Road, Nottinghill,Victoria, Australia 3168. e-mail: [email protected] Minshew’s complex information processing theory of autism (Minshew and Goldstein, 1998; Minshew et al., 1997) emphasizes the equal importance of understanding not only areas of neuropsychological deficit, but also autism © 2008 SAGE Publications and The National Autistic Society Vol 12(3) 249–260; 088754 1362-3613(200805)12:3 © 2008 SAGE Publications (Los Angeles, London, New Delhi and Singapore) DOI: 10.1177/1362361307088754 K E Y W O R D S Asperger’s disorder; autism; inhibition of return; visual search at UNIV OF TEXAS AUSTIN on November 4, 2008 http://aut.sagepub.com Downloaded from areas which are preserved as a means for appreciating the full behavioural impact of the disorder (Minshew et al., 1997). An intact or superior ability to detect unique items in visual search tasks (e.g. ‘finding an R target hidden among P and Q distractors’) is emerging as a significant aspect of the neuropsychological profile of autism (O’Riordan, 2004, p. 230). O’Riordan’s series of experiments manipulating search task parameters has indicated that superior search in individuals with autism is underpinned by an enhanced ability to discriminate between items (O’Riordan, 2004). Plaisted et al. (1998) note that this enhanced ability to visually detect items is ‘at odds’ with the body of research showing that individuals with autism in fact have significant difficulties with tasks measuring visual orientation and attentional set-shifting. To account for this apparent anomaly in research findings, Plaisted et al. (1998) point to possible differences in domains other than visual attention which may account for enhanced item detection and superior search performance, for example, weak central coherence, reduced generalization of responding. A possibility that has not yet been explored in the literature is that individuals with autism may also be better at search tasks due to a more pronounced inhibition of return (IOR). IOR is a central cognitive mechanism which supports ‘perceptual-motor interactions within complex environments’ (Tipper et al., 1996, p. 1289). IOR was demonstrated experimentally by Posner et al. (1984) who showed that reaction time to a target is shorter when the target and cue are presented at the same location, compared to when they are presented in a different location, if the cue-totarget delay is less than 300 ms. However, if the cue and target are separated by more than 300 ms but less than 2000 ms, the reverse pattern occurs, that is, reaction time is slower when the cue and target appear in the same location compared to when they appear in different locations (i.e. IOR). This highly adaptive phenomenon ensures that attention is distributed across the environment to novel locations and does not perseverate on a single, irrelevant location (Tipper et al., 1996). Thus, an important function of IOR is to improve visual search efficiency (Klein and MacInnes, 1999). While a deficient IOR mechanism would make the simplest of search tasks difficult (for example, when searching for a letter ‘R’ target, the participant might tend to repeatedly look in locations of the visual array which have previously been searched and ruled out), an intact or superior IOR would promote visual search to novel locations, expediting the search task. Klein and MacInnes (1999) have shown that IOR facilitates visual search in normally developing individuals using a Where’s Waldo?TM paradigm, a paradigm which may be loosely associated with the tasks used to demonstrate superior search ability in individuals affected by autism and Asperger’s disorder (e.g. Jolliffe and Baron-Cohen, 1997; O’Riordan, 2004). A U T I S M 12(3)