Abstract
Whether focused visual attention can be divided has been the topic of much investigation, and there is a growing body of evidence that, at least under certain conditions, attention can be divided and deployed as two or more independent foci. Three experiments were conducted to examine whether attention can be divided from the outset or whether, instead, attention is divided gradually over time. To this end, we adapted the methodology of Jefferies, Enns, and Di Lollo (2015), who utilised a dual-stream Attentional Blink paradigm and two pairs of letter targets. One component of the AB, Lag-1 sparing, is known to occur only if the second target-pair appears within the focus of attention. By presenting the second target-pair at various spatial locations, we were thus able to probe the spatial distribution of attention. By systematically manipulating the stimulus-onset-asynchrony between the targets, we were also able to track how the spatial distribution of attention changed over time. The results showed clearly that even under conditions which encourage the division of attention, the attentional focus is first deployed briefly in unitary form before being divided. Our findings also showed that, consistent with previous findings, attention could only be maintained in divided form briefly before settling on a single location (see Dubois, Hamker, & VanRullen, 1997). The present findings suggest that although attention can be divided, it is divided for an even more transient period than has previously been thought, suggesting that a unitary focus of attention may be the "default" mode of attention.
Meeting abstract presented at VSS 2017