The influence of eye movements on contrast sensitivity and gain response in peripheral vision W Harrison1, M Kwon2, P Bex2 |
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1Schepens Eye Research Institute, MA, United States |
| Saccadic eye movements dynamically alter visual processing: it has previously been shown that just prior to a saccade, low spatial frequencies are suppressed; and, for the saccade target, perceived contrast increases and visual crowding diminishes. The aim of this study was to more fully characterize the changes in visual perception immediately before the execution of a saccade, and to provide a functional account of these changes. We first measured the contrast sensitivity function at the goal of an impending saccade. Relative to when no eye movements were imminent, we found only partial support for active suppression of low spatial frequencies within 50 ms prior to saccade onset. Furthermore, we found no evidence of an enhancement of contrast sensitivity at any spatial frequency. We next quantified contrast discrimination thresholds during steady fixation and within 50 ms prior to a saccade. The resulting dipper functions overlapped across the range of pedestals tested (0% to 50% contrast), showing no appreciable changes in thresholds during saccade preparation. Thus, our data argue against the hypothesis that eye movements signals change response gain. Instead, our data suggest that previous demonstrations of enhanced perception at the saccade goal result from changes in higher levels of processing. |
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