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B. R. Beutter, M. P. Eckstein, L. S. Stone; Correlated saccadic and perceptual decisions in a visual-search detection task reveal spatial-filter overlap. Journal of Vision 2001;1(3):263. doi: 10.1167/1.3.263.
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© ARVO (1962-2015); The Authors (2016-present)
Introduction: We have shown that for matched processing times, the accuracy of the 1st saccade and the perceptual decision in visual-search detection tasks are, on average, nearly the same (Stone et al., Neurosci. Abstr.. 1999; Beutter et al., ARVO 2000). If saccadic and perceptual decisions are made using similar receptive fields (spatial filters), then for trials with identical external noise samples, the two decisions should be correlated. Methods: We recorded eye movements and perceptual responses of 3 observers (1 naive) performing a 10AFC search task under 2 conditions. In a long condition (up to 4s), observers made saccades to search the display and we defined the 10AFC saccadic decision as the element location closest to the endpoint of the 1st saccade. In a short condition (150ms duration to match saccadic processing time), central fixation was required, and we recorded the 10AFC perceptual decision. The target (a blurred 21′ disk) was added to a Gaussian white noise background (rms contrast: 26%) and was randomly chosen to be in one of ten 2.4 deg boxes at 5.9 deg eccentricity with one of 5 interleaved target SNRs (2.0, 2.9, 4.2, 5.2, 6.3). For each SNR, observers searched the same 100 noisy images 3 times under both conditions. We computed the average auto- and cross-correlations of the saccadic and perceptual decisions across repeated presentations of each noise image. We then used the relationship between the cross- and auto-correlations to calculate the spatial-filter overlap (normalized dot-product). Results: For the 3 observers, the cross-correlations were higher than expected from independent processes at all SNRs, and the computed spatial-filter overlaps were 75, 86, and 88%. Conclusions: Our data show that saccades and perception are similarly influenced by external noise, consistent with detection mechanisms with similar overall receptive fields. These results suggest a shared neural processing stage underlying target detection and selection for both saccades and perception.
(NASA RTOPs 711-51-12 & 131-20-30 to LS and NCC 2-1027
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