Abstract
Visual attention can be proactively directed to locations in space (Posner, 1980; Chung and Jiang 1998), to object features (Treisman and Gelade, 1980; Kok et al., 2012) and to points in time (Coull & Nobre, 1998). In our environment, spatial, temporal and feature-based expectations interact to shape behaviour (Nobre and Rohenkohl, 2014). Temporal expectations have been proposed to guide perception when accompanied by congruent spatial expectations (O’Reilly, 2008; Rohenkol et al., 2014). In two complementary studies, we set out to investigate whether cued temporal expectations can guide visual perception, even in the absence of spatial expectations, in a continuously changing environment. On each trial, participants (online study: N = 49, in-person study: N = 24) were presented with a stream of bilaterally appearing coloured circles, similar to a dual-stream rapid serial visual presentation task. Each stream was composed of three coloured targets and between 6 and 9 distractors. On each trial one of the targets always appeared at a fixed early time, another appeared at a fixed late time, and the other could appear at any time. A coloured cue at the beginning of each trial indicated which of the three target circles was relevant. Specifically, participants were asked to respond to the side (left or right) in which the cued target appeared in any given trial. We found that participants were faster and more accurate in detecting targets that occurred at an expected time (early or late), compared to the randomly timed targets, even though participants had no information regarding the likely location of the target. From these results, we conclude that temporal expectations can facilitate performance in the absence of concomitant spatial expectations and in dynamically unfolding streams of visual stimuli.