Abstract
Purpose: It has been found that exogenous cueing reduces the visual latency of a subsequent target. While it is commonly thought that attention accelerates processing within its locus, other explanations such as response bias and sensory facilitation are also possible. Our goal was to evaluate the relative role of spatial attention, response bias, and sensory facilitation on measurements of the latency of visual perception. Methods: In separate blocks within each of two separate experiments, subjects judged the perceived synchrony (SJ) or temporal order (TOJ) of two colored targets presented at pseudorandom locations within an annulus of fixed eccentricity with a variable onset delay between them. In Experiment 1, one of the targets was preceded by a spatial cue. In Experiment 2, trials were mixed with either both targets cued, one target cued by a single cue, or one target cued by one of multiple cues occurring in different locations to reduce the attention allocated to each. Results: In Experiment 1, the TOJ was maximally uncertain when uncued target led the cued target by 48 ms, consistent with published results. However, the maximum SJ occurred when the uncued target led the cued target by only 11 ms. The difference is likely due to response biases present in the TOJ but not in the SJ. In Experiment 2, increasing the number of cues reduced but did not eliminate the latency effect in both the TOJ and SJ. Conclusions: TOJs are often confounded by response biases that are reduced or eliminated by using a SJ. Since the perceived asynchrony of the cued and uncued target persists even with a large number of cues, the effect on the SJ seems to be due to the sensory facilitation that transient cues produce rather than the attention that they draw.