Beutter B, Eckstein M P, Stone L S, 2004, "Saccadic and perceptual classification images have similar receptive-field shapes in a contrast-discrimination visual-search task" Perception 33 ECVP Abstract Supplement
Saccadic and perceptual classification images have similar receptive-field shapes in a contrast-discrimination visual-search task
B Beutter, M P Eckstein, L S Stone
In a visual-search task, we compared saccadic and perceptual processing by computing classification images from incorrect decisions. Two observers searched for the brightest circle in a spatial, 8-alternative forced choice (8AFC) contrast-discrimination task. The target (contrast 18%) and distractors (contrast 15%) were equally spaced (eccentricity 5.8 deg) blurred (8 min of arc) circles (57 min of arc radius), with added external, white, Gaussian noise (24% rms contrast). In the saccadic processing condition (duration 4 s), observers searched with eye movements. The 8AFC saccadic decision was defined as the element location nearest the 1st saccade's endpoint. In the separate perceptual processing condition, observers made an 8AFC perceptual decision with the stimulus duration (117 - 150 ms) chosen so that the perceptual processing time was similar to the processing time available for the 1st saccade. Radial difference of Gaussian (DOG) functions containing both excitatory and inhibitory regions fit both the saccadic and perceptual classification images well (mean reduced χ2 = 1.07, 0.99, respectively). The shapes of the saccadic and perceptual receptive fields were nearly identical for both observers (dot product of normalised DOG fits were > 0.99), but were both significantly different from that of the target. These results suggest that saccades and perception share visual information about search-target shape.
[Supported by NASA Airspace Operations System Program, NASA WBS 21-711-80-03.]
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