Abstract
Purpose: Temporal attention is the prioritization of visual information at specific points in time. We used a new experimental approach to test the hypothesis that voluntary temporal attention selects among successively appearing stimuli. This approach allowed us to evaluate whether attention enhances discriminability by redistributing limited attentional resources in time. Methods: On each trial, two Gabor stimuli (S1 and S2) were presented successively at the same peripheral location, with an SOA of 250 ms. Each stimulus was tilted slightly clockwise or counterclockwise, with independent tilts for S1 and S2. The amount of tilt was determined individually for each participant using a staircase procedure. An auditory pre-cue instructed participants in advance of each trial to attend to S1 or S2 (with 75% validity) or to both stimuli (via a neutral, uninformative pre-cue). A response cue instructed participants to report the orientation of either S1 or S2. A match between the pre-cue and response cue yielded a valid cue, a mismatch, an invalid cue. Results: Because two stimuli were presented on every trial and only the temporal allocation of attention varied, we could measure how temporal attention affected perception of both S1 and S2. Performance accuracy was higher for valid than for invalid cues for both S1 and S2 (n=10). We also observed main effects of both benefits for valid cues and costs for invalid cues, compared to neutral cues. Such perceptual tradeoffs between two stimuli due to attention are a hallmark of selectivity. Conclusion: Attending to one stimulus improves discrimination performance for that stimulus relative to other stimuli presented either slightly earlier or later in time, even when the stimuli are not masked and there is no uncertainty about stimulus timing. We conclude that voluntary attention is selective in time.
Meeting abstract presented at VSS 2015