Abstract
Attention operates at multiple processing stages. Specifically, attention enhances weak sensory signal at the perceptual stage, while it also serves to consolidate sensory representations into working memory at the central stage. The present study tested the interaction between these distinct types of attention. In the first experiment, participants were required to detect a target letter (target 1, T1) imbedded in a rapid serial visual presentation of digit distractors. The centrally presented RSVP was followed by another visual task of identifying the orientation of a Gabor grating (target 2, T2) presented in periphery. Importantly, the grating was preceded by a cue stimulus (green outlined square), which was presented either at the T2 location (valid) or elsewhere (invalid). The probability that the cue and T2 locations match was chance (25 %), rendering the cue non-informative of the T2 location. We also manipulated the SOA between the T1 and cue presentations (200 ms vs. 900 ms). The results showed that when the T1-cue SOA was long, T2 accuracy for the valid trials was significantly greater than for invalid trials, p < .005, revealing a significant perceptual effect of the spatial attention cue. By contrast, such perceptual effect of attention was not observed when the SOA was short, p > .22, indicating that the process of encoding the T1 into working memory impaired the perceptual enhancement by spatial attention. In a second experiment, the T2 was surrounded by distractors, evoking the target location uncertainty and stimulus-driven competition. In this case, contrary to Experiment 1, the effect of spatial cue was invariant of the T1-cue SOA, p's < .01. These results suggest that the perceptual enhancement of attention in the absence of distractors depends on the availability of processing resources recruited for working memory encoding, whereas the noise reduction process by attention does not.
Meeting abstract presented at VSS 2017