Abstract
Tasks requiring divided attention are often performed better when attended items are presented bilaterally between the right and left visual hemifields, rather than contained within a single hemifield. This bilateral field advantage appears particularly pronounced for spatial tasks, such as multiple-object tracking (Alvarez & Cavanagh, 2005), spatial working memory (Delvenne, 2005; Umemoto, Drew, Ester, & Awh, 2010), and volitional perception of ambiguous motion (Nothelfer, Suzuki, & Franconeri, VSS 2015). However, it remains unclear whether these effects reflect hemifield-specific attentional control mechanisms, or instead result solely from hemifield-limited spatial interference during encoding. If hemifield-specific control mechanisms contribute to the bilateral field advantage, then maintaining spatial information should become more difficult when attended items cross between the two hemifields. Observers performed a spatial working memory task that required remembering the locations of dots presented in two separate grids. The grids were located in diagonally opposite quadrants during presentation of the dots (e.g., one grid in the top-right, and one grid in the bottom-left). After two dots were briefly presented in each grid, the grids simultaneously shifted either vertically to a new quadrant in the same hemifield (within-hemifield movement), or horizontally to a new quadrant in the opposite hemifield (between-hemifield movement), before a cue appeared in one grid. Observers were more accurate reporting whether this cue corresponded to a previous dot location following within-hemifield movements (M=86.0%) than following between-hemifield movements (M=79.5%; t(59)=5.67, p< .001). This crossover cost did not occur for a color working memory task (Experiment 2), but was found for a separate spatial attention task that required observers to maintain two distinct ambiguous motion perceptions (one vertical and one horizontal; Experiment 3). Together, these results provide converging evidence that hemifield-specific control mechanisms 1) contribute to the bilateral field advantage, and 2) may be a unique signature of spatial working memory and attention.
Meeting abstract presented at VSS 2018