Increased Capacity for Time Perception in Autism Spectrum Disorder

Background:

Previous Autism Spectrum Disorder (ASD) research portrays a mixed picture of attentional abilities with demonstrations of both enhancements (e.g. superior visual search performance) and deficits (e.g. higher distractibility) compared to neurotypical controls.

We have used load theory of attention and cognitive control (e.g. Lavie, 2005) to offer a potential resolution. Load theory states that distractor processing depends on the extent to which a task engages full capacity (in conditions of high load) or leaves spare capacity that ‘spills over’ resulting in distractor processing. Our previous work suggests that ASD is characterised by an increase in visual perceptual capacity. This enhanced capacity leads to the ability to process additional stimuli, which can manifest both as increased distractibility (Remington et al 2009) and higher detection sensitivity (Remington et al 2012). Thus our resolution of the previous discrepancies in the literature accounts for the superior performance seen on detection tasks (e.g. visual search; Embedded Figures Task) and the susceptibility to distraction; which we assert comes not from a filtering deficit but from increased perceptual capacity.

Objectives:

Thus far, increased perceptual processing capacity associated with ASD has only been established in the visual domain. Here we examine what effect the enhanced capacity has on another important faculty; namely that of time perception. Does this superiority extend into the temporal domain?

Methods:

Young high functioning adults with ASD and a group of age and IQ-matched controls performed a Rapid Serial Visual Presentation task. A stream of crosses of varying colour and orientation (upright/inverted) was presented and participants were asked to detect either any red cross (low load condition) or upright yellow and inverted green crosses (high load condition). The total duration of each stream was 6 or 12 seconds. Following each stream, participants were required to reproduce the time duration of the stream.

Results:

Our findings indicate that for neurotypical controls, time-estimation ability was reduced under high perceptual load. The young adults with ASD were more accurate than controls for the longer stream duration (12 seconds) and for both durations the  accuracy of time estimation in ASD was not reduced by the level of visual perceptual load in the stream.

Conclusions:

These results indicate that increased visual perceptual capacity in ASD confers an advantage in time perception.

Despite some previously reported deficits in short-duration time-perception within the auditory domain (Szelag et al 2004; Gowen & Miall, 2005; Martin et al 2010), our findings demonstrate that under certain conditions (i.e. when visual, rather than auditory processing capacity is loaded) individuals with ASD can outperform typical controls. These findings provide new line of support for our hypothesis of increased perceptual processing capacity in ASD.

This further establishes our resolution regarding increased perceptual capacity, extends the findings to an additional domain and suggests that increased perceptual capacity in ASD may underlie both enhancements and deficits seen within the condition.