Abstract
Introduction: Extant research indicates that visual attention samples the environment about seven times per second (VanRullen, Carlson & Cavanagh, 2007). Research also suggests that separate neural resources mediate attention to the left and right visual fields (LVF and RVF, respectively; Alvarez & Cavanagh, 2005). Here, we investigated whether these LVF and RVF resources could operate additively to increase attention's temporal resolution. Method: Denison University undergraduates viewed bilateral-stream RSVP displays containing two successive targets (T1 and T2) and reported target identities on each trial. Four target-hemifield configurations (LL, RR, RL, LR) were varied randomly across trials. In Experiment 1, the LVF and RVF streams were either temporally synchronized or asynchronized such that new visual information appeared at either 7.5 or 15 Hz, respectively. Experiment 2 comprised the asynchronized condition from Experiment 1, along with a "triple" condition that embedded T1 and T2 within separate LVF-only or RVF-only stimulus triplets at 15 Hz. Results: Experiment 1: Doubling the visual information rate from 7.5 Hz (synchronous condition) to 15 Hz (asynchronous condition) did not impair T2|T1 accuracy (p=.162, n.s.). Also, T2|T1 accuracy for LVF-T2s significantly exceeded that for RVF-T2s (p<.001). Experiment 2: T2|T1 accuracy in the asynchronous condition significantly exceeded that in the laterally faster triple condition when both targets appeared within the same hemifield (p<.001). This effect vanished when the two targets appeared in separate hemifields. T2 accuracy also significantly exceeded T1 accuracy in the triple condition's RL hemifield configuration (p<.05), indicating a LVF advantage. Conclusion: Our findings suggest that independent LVF and RVF neural resources can cooperate to effectively double attention's temporal resolution, given appropriate stimulus conditions. Additionally, the present LVF advantages are consistent with accounts of a right parietal lobe "when" pathway (Battelli, Pascual-Leone & Cavanagh, 2007).
Meeting abstract presented at VSS 2014