Reduced Competition and Visual Field Asymmetries in a Dual-Stream Attentional Blink Paradigm in Individuals with High Levels of Autistic Symptomatology

Background: The attentional blink (AB) paradigm has been used to explore the temporal and spatial dynamics of visual attention (Raymond, Shapiro, & Arnell, 1992). In a typical AB paradigm, two target letters are embedded in a rapid stream of digit distracters. Although identification accuracy of the first target is normally very high, identification of the second target is impaired when it appears in close temporal proximity to the first. A notable exception to this occurs when the second target is presented directly after the first target (at the ordinal position known as Lag 1). Using a dual-stream AB paradigm, in which two streams of distractors are displayed, one to the left and one to the right of fixation, Verleger et al. (2009) showed that when T1 and T2 are presented in opposite streams, T2 is identified more accurately when it is presented in the left visual field. This left visual field advantage did not occur when T1 and T2 were presented in the same stream. They conclude that this is evidence for a right-hemisphere advantage when singling out targets in time.

Objectives: English, Maybery, and Visser (2015) showed a tendency in individuals with autistic traits to attend less to the left side suggesting a reduction in right hemisphere activation. Accordingly, we used a dual-stream AB paradigm, to further assess the nature of visual field asymmetries in individuals high in autistic traits.

Methods: Eighty-two young adults were allocated to either High-AQ or Low-AQ groups based on scores on the autism-spectrum quotient (AQ; Baron-Cohen, 2001). Each participant completed a dual-stream AB task in which two target letters were embedded in streams of digit distracters. One stream was presented to the left of a central fixation point, the second stream appeared to the right of fixation. The two targets appeared randomly and unpredictably in either the same stream as one another or in opposite streams. On a third of trials, the second target appeared immediately after the first (Lag 1); on another third of the trials the targets were separated by a single digit distracter (Lag 3); on the remaining trials, the targets were separated by 8 distracters (Lag 9). The stimulus onset asynchrony between items in the stream was 80 ms.

Results: The Low-AQ grouped showed the anticipated differences, and T2 was identified more efficiently in the left than right visual field. Visual field differences were markedly absent for the High-AQ group, who identified T2 equally well in both hemifields.

Conclusions: Individuals with High- as compared to Low-AQ scores displayed the lack of an attentional bias for the left visual field, extending evidence of diminished neural asymmetry in autism. This suggests that enhanced perceptual processing or snappy attentional gating might eliminate hemispheric competition leading to similar results in the same and different streams, regardless of the visual field in which T2 appeared. The apparent absence of hemispheric asymmetry that is characteristic of typical individuals may reflect a cognitive strength in right hemisphere functioning, leading to similar perceptual processing in both visual fields.