Higher levels of autistic traits in the general population are associated with reduced visual field asymmetries in a dual-stream attentional blink task

Background

Spatial attention is typically right-hemisphere lateralized, resulting in a bias to preferentially process information in the left visual field (VF). As atypical hemispheric lateralization is considered a fundamental neurobiological feature of autism, we assessed whether it is also evident in people who display higher levels of autistic-type traits but do not meet the criteria for a clinical diagnosis of autism. In doing so, we used a dual-stream attentional blink task – a task with heavy processing demands and stimuli displayed simultaneously in both VFs – to elicit inter-hemispheric competition and assess visual field asymmetries.

Method

The participants were 82 university students, who had never been clinically diagnosed with autism, divided into two groups based on the level of autistic traits that they displayed on the Autism Quotient scale (AQ; Baron-Cohen et al., 2001). Two simultaneous streams of digit-distractors were displayed, one in each VF, and the participants’ task was to identify two letter-targets that were displayed unpredictably in the left or right stream.

Results

We found reduced VF asymmetries in higher autism-trait individuals, with the magnitude of the asymmetry correlating with AQ score.

Conclusions

We suggest that the reduced VF asymmetries in individuals with higher autism traits may be due to increased perceptual processing capacity (Remington et al., 2009), which reduces hemispheric competition and, thus, visual field asymmetries. The findings also highlight that even subtle differences in the degree of autistic traits in the general population may be associated with differences in visual attention.