Bilateral Field Advantage in Visual Enumeration

Abstract

A number of recent studies have demonstrated superior visual processing when the information is distributed across the left and right visual fields than if the information is presented in a single hemifield (the bilateral field advantage). This effect is thought to reflect independent attentional resources in the two hemifields and the capacity of the neural responses to the left and right hemifields to process visual information in parallel. Here, we examined whether a bilateral field advantage can also be observed in a high-level visual task that requires the information from both hemifields to be combined. To this end, we used a visual enumeration task—a task that requires the assimilation of separate visual items into a single quantity—where the to-be-enumerated items were either presented in one hemifield or distributed between the two visual fields. We found that enumerating large number (>4 items), but not small number (<4 items), exhibited the bilateral field advantage: enumeration was more accurate when the visual items were split between the left and right hemifields than when they were all presented within the same hemifield. Control experiments further showed that this effect could not be attributed to a horizontal alignment advantage of the items in the visual field, or to a retinal stimulation difference between the unilateral and bilateral displays. These results suggest that a bilateral field advantage can arise when the visual task involves inter-hemispheric integration. This is in line with previous research and theory indicating that, when the visual task is attentionally demanding, parallel processing by the neural responses to the left and right hemifields can expand the capacity of visual information processing.

Bilateral and two-item advantage in subitizing

“…In contrast to the present finding, Delvenne et al (2011) only observed a bilateral field advantage in counting. This difference may in part be explained by the fact that Delvenne et al (2011) did not examine RTs. The present results show that a bilateral field advantage can be observed in RTs, although a similar effect is not observed in enumeration accuracies.…”

“…If similar capacity limitations underlie multiple object tracking and subitizing, as is predicted by theories (Pylyshyn, 1989; and empirical observations (Chesney & Haladjian, 2011), a bilateral advantage should also be observed in subitizing. A recent study failed to find evidence for bilateral field advantage in subitizing (Delvenne et al, 2011), but only examined enumeration accuracy and variation. However, due to the very high precision of subitizing, it is possible that a bilateral advantage in subitizing may only be observed in enumeration times.…”

A Bilateral Advantage in Controlling Access to Visual Short-Term Memory

“…Chakravarthi & Cavanagh 2009;Reardon, Kelly, & Matthews, 2009), rapid item identification (e.g. Awh & Pashler, 2000;Scalf, Banich, Kramer, Narechania, & Simon, 2007) and visual enumeration (Delvenne, Castronovo, Demeyere, & Humphreys, 2011).…”

Remapping time across space

“…Behavioral data demonstrate this in two ways. First, several studies have revealed a bilateral attentional advantage, i.e., better performance for targets distributed across the left and right visual fields than for targets restricted to just one lateral hemifield (Awh & Pashler, 2000;Alvarez & Cavanagh, 2005;Delvenne, 2005;Chakravarthi & Cavanagh, 2009;Reardon, Kelly, & Matthews, 2009;Delvenne, Castronovo, Demeyere, & Humphreys, 2011). 1 This bilateral attentional advantage suggests independence between the neural resources that govern attention to the left visual field (LVF) and those governing attention to the right visual field (RVF).…”