Enhanced Discrimination of Novel, Highly Similar Stimuli by Adults with Autism During a Perceptual Learning Task

Abstract

High-functioning adults with autism and control adults were tested on a perceptual learning task that compared discrimination performance on familiar and novel stimuli. Control adults were better able to discriminate familiar than novel stimuli-the perceptual learning effect. No perceptual learning effect was observed in adults with autism although they discriminated the novel stimuli significantly better than control adults. This enhanced discrimination learning about novel, but not familiar, stimuli in autism is discussed in relation to two current hypotheses of information processing in autism-weak central coherence and reduced attention-switching-and a new third hypothesis, which suggests that features held in common between stimuli are processed poorly and features unique to a stimulus are processed well in autism.

Intact Spectral but Abnormal Temporal Processing of Auditory Stimuli in Autism

“…interrupts transient auditory memory formation), such that subjects with autism and controls resort to the same processing strategy. Several studies had already found enhanced simple lowlevel visual processing (O'Riordan et al 2001;Plaisted et al 1998) and spared (Spencer et al 2000;Blake et al 2003) or diminished complex low-level visual processing (Milne et al 2002). In the auditory domain, enhanced simple low-level processing had been reported for pitch discrimination and chord disembedding (Bonnel et al 2003;Heaton 2003), in which perceptual performance depends on spectral processing.…”

Configural processing in autism and its relationship to face processing

“…While some studies have shown that autistic individuals are better able to identify the local than global letters in compound stimuli and to focus on local elements (sometimes to an even greater degree than is true for the control subjects) in visual search (Plaisted, 2000;Plaisted et al, 1998), this is not always the case. For example Mottron and his colleagues (Mottron, Burack, Stauder, & Robaey, 1999;Mottron, Burack, Iarocci, Belleville, & Enns, 2003) have reported that autistic individuals do not differ from non-autistic subjects in deriving the identity of the global letter of compound stimuli (although perhaps even more surprising is the absence of the expected global advantage for normal individuals in some of these studies).…”

“…1 For example, autistic individuals fail to take the entire visual context into account (Happé, 1996;Ropar & Mitchell, 1999) and fail to perceive impossible geometric figures, a task which requires part integration (Mottron & Belleville, 1993). Using a wide variety of paradigms, investigations have also revealed that autistic individuals show enhanced detection of local targets in visual search (Plaisted, O'Riordan, & Baron-Cohen, 1998;Plaisted, Swettenham, & Rees, 1999), perform well on tasks such as Block Design and Object Assembly that require a local focus (Minshew, Goldstein, & Siegel, 1997) and exhibit superior performance in detecting embedded figures (Happé, 1999;Jolliffe & Baron-Cohen, 1997;Shah & Frith, 1983). One recent study has revealed that autistic children use gestalt grouping heuristics significantly less often than controls do, resulting in difficulties appreciating interelement relationships (Brosnan, Scott, Fox, & Pye, 2004).…”

Sensory Integration and the Perceptual Experience of Persons with Autism

“…According to the ''weak central coherence'' theory, the ability to integrate information across a variety of contexts (perception, attention, linguistic, semantic) for higher-level meaning is impaired (Frith, 1989;Frith & Happe´, 1994;Happe´, 2005). Temporal binding is identified as the key process that is disrupted and likely implicated in the perceptual as well as higherorder deficits observed in autism (Brock et al, 2002), whereas in other studies, processing atypicalities are specifically associated with enhanced sensory processing or discrimination in various modalities (Mottron & Burack, 2001;O'Riordan, Plaisted, Baron-Cohen, & Driver, 2001;Plaisted, O'Riordan, & Baron-Cohen, 1998). Researchers of the neurological aspects of the disorder suggest that structural abnormalities in the cerebellums of persons with autism cause a disruption in the attentional system, particularly in the ability to shift attention within the visual modality and between auditory and visual modalities (Ciesielski, Knight, Prince, Harris, & Handmaker, 1995;Courchesne, Townsend, & Akshoomoff, 1994;Martineau et al, 1992;Townsend, Harris, & Courchesne, 1996).…”