Impact of microsaccades on visual shape processing
| Autor: | Ken W. S. Tan, Paul V. McGraw, Elizabeth M. Haris, Chris Scholes, Neil W. Roach |
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| Rok vydání: | 2021 |
| Předmět: | |
| Zdroj: | Journal of Neurophysiology. 125:609-619 |
| ISSN: | 1522-1598 0022-3077 |
| Popis: | Sensitivity to subtle changes in the shape of visual objects has been attributed to the existence of global pooling mechanisms that integrate local form information across space. Although global pooling is typically demonstrated under steady fixation, other work suggests prolonged fixation can lead to a collapse of global structure. Here, we ask whether small ballistic eye movements that naturally occur during periods of fixation affect the global processing of radial frequency (RF) patterns-closed contours created by sinusoidally modulating the radius of a circle. Observers were asked to discriminate the shapes of circular patterns and RF-modulated patterns while fixational eye movements were recorded binocularly at 500 Hz. Microsaccades were detected using a velocity-based algorithm, allowing trials to be sorted according to the relative timing of stimulus and microsaccade onset. Results revealed clear perisaccadic changes in shape discrimination thresholds. Performance was impaired when microsaccades occurred close to stimulus onset, but facilitated when they occurred shortly afterward. In contrast, global integration of shape was unaffected by the timing of microsaccades. These findings suggest that microsaccades alter the discrimination sensitivity to briefly presented shapes but do not disrupt the spatial pooling of local form signals. |
| Databáze: | OpenAIRE |
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