Abstract
Goal Visual responses at the saccade landing location are enhanced before the eyes move, a phenomenon known as presaccadic attention. Here, we investigate whether such enhancement is mediated by contrast gain or response gain. Method In a fine orientation discrimination task, the target was a Gabor patch (4 cpd) presented at one of two locations (8° left or right of fixation). The target orientation was tilted either clockwise or counterclockwise from vertical on each trial. The degree of tilt was titrated for each observer. We tested the target at 9 contrast levels (5%-95%). In the saccade condition, a pre-cue instructed observers to saccade to the cued location. Shortly after the pre-cue (12-224 ms), the stimulus was presented (35 ms) at the cued location. In the neutral condition, a pre-cue pointed to both locations instructing observers to maintain fixation. Observers reported the orientation of the target following an auditory response cue (400 ms after target offset). The frequency of the response cue (low or high tone) indicated the target location (left or right). Results We binned the data relative to saccade onset. We fit performance (d') as a function of contrast with a Naka-Rushton function. The three free parameters were dmax, C50 and n, representing asymptotic performance, semi-saturation contrast and exponent, respectively. Compared to the neutral condition, presaccadic attention increased asymptotic performance at high contrasts, indicating a response gain change. This modulation became more pronounced closer to the time of saccade onset. We did not observe a change of semi-saturation contrast between conditions. Conclusion Presaccadic attention enhances the saccade target through response gain. This finding serves as a critical step toward understanding the neural computations underlying presaccadic attention.
Meeting abstract presented at VSS 2018