Abstract
Goal: Voluntary temporal attention, the prioritization of visual information at task-relevant points in time, improves perceptual sensitivity. However, little is known about how temporal attention affects the neural representation of visual information. Here we investigated whether and how temporal attention affects orientation representations. Methods: In two experiments, we used a two-target temporal cueing task to manipulate voluntary temporal attention and measured the effects on orientation representations using MEG decoding. On each trial, two grating targets (T1 and T2), each independently tilted around vertical or horizontal, appeared sequentially at the same location, separated by a 300-ms interval. An auditory precue (75% validity) before the targets instructed observers to attend to T1 or T2. An auditory response cue after the targets instructed observers to report the tilt (clockwise or counter-clockwise) of either T1 or T2. In trials where the precue directed temporal attention to T1, T1 was attended and T2 was unattended, and vice versa when the precue was to T2. The temporal cueing protocol was similar in the two experiments, except that in Experiment 1, the targets were presented on a gray background, whereas in Experiment 2, the targets were superimposed on 20-Hz flickering noise patches. To measure time-resolved orientation representations for each target, we decoded vertical vs. horizontal orientation across time using a linear support vector machine. Results: In both experiments, temporal attention improved behavioral accuracy, and it increased orientation decoding accuracy for T1. The improvement occurred 235-300 ms and 195-260 ms after T1 onset for Experiments 1 and 2, respectively, according to cluster permutation tests. There was no evidence for improved T2 decoding accuracy in either experiment. Conclusions: Voluntary temporal attention enhanced the orientation representation of the first target. This sensory-level change reveals a possible neural mechanism of how temporal attention could improve visual perceptual sensitivity.