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Dagmar Wismeijer, Karl Gegenfurtner; Eye movements when viewing oriented noisy textures. Journal of Vision 2011;11(11):558. doi: https://doi.org/10.1167/11.11.558.
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© ARVO (1962-2015); The Authors (2016-present)
We redirect our eyes approximately 3 times per second to bring a new part of our environment on to our fovea. How a scanning path is planned, is still an unsolved matter. We questioned whether orientations, ubiquitously present in our environment, can be helpful guides in redirecting our point of fixation. To this end, we studied saccades made in response to oriented Gabor patches that were embedded in circular patches (radius of 8°) of pink (1/f) noise. We varied the saliency of randomly oriented Gabors, that either had a high or a low spatial frequency (2 & 16 cycl/°), by changing their contrast. Five subjects were instructed to fixate the center of the screen and then were free to make eye movements during the 2 s presentation of the stimuli. We asked subjects to report the perceived stimulus orientation after it had disappeared, by rotating a black line using the mouse. Eye movements were measured using the head-mounted Eyelink II system. We analyzed saccade direction of both small (≤1°) and large (>1°, <10°) saccades made during stimulus presentation. The data showed that in the lowest contrast conditions, the orientations were hard to distinguish (for only 2 subjects in these 2 conditions the perceptual response was significantly correct (Rayleigh test on corrected response)). The saccade directions were random, similar to search like behavior. In the other conditions, especially for the low spatial frequency Gabor, perceptual responses were almost always correct. For 3 out of 5 subjects, the saccadic responses were aligned with the orientation of the Gabor (significant Rayleigh test result), for saccades with an amplitude larger than 1° (and smaller than 10°). Our results show that orientation does have an effect on saccadic eye movements. Saccades, with amplitudes larger than 1°, are made predominantly along the orientation of these textures.
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