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Min Zhao, Brian S. Schnitzer, Barbara A. Dosher, Eileen Kowler; Attention during pauses between successive saccades: Task interference vs. modulation of contrast-gain. Journal of Vision 2010;10(7):160. doi: 10.1167/10.7.160.
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Perceptual performance is better at the target of a saccade than other locations (e.g., Gersch et al., 2009).To better understand pre-saccadic attention shifts, we studied perceptual discrimination across different stimulus contrasts during pauses between successive saccades.
Displays contained 4 outline squares (1.4° on a side) located at the corners of an imaginary square. Sequences of saccades were made in a V-shaped path from one corner square, to center, to another corner square. When the eye reached the center, perceptual targets (oriented letter T's) appeared inside each eccentric square. The orientation of a randomly-selected T was reported after scanning was completed. Orientation discrimination was poor (<75% correct) at all test locations other than the saccadic goal, even at the highest contrast.These performance losses could be due to selective decay of visual memory (Gersch et al., 2008).
Selective memory was not the only factor, however, because results were similar in a second experiment in which a single perceptual target (right or left tilted Gabor; +/- 22.5o) was presented in each trial. Durations of pauses between saccades were prolonged when the Gabor was detected at a location other than the saccadic goal, reflecting an attempt to improve perceptual discrimination by delaying the saccade. This strategy succeeded when perceptual reports were required on most (80%) of the trials. When reports were required in only 20% of trials, performance at non-goal locations fell across the contrast range, reaching an asymptotic level of only 85% correct at 60% contrast.
These results extend findings that pre-saccadic attention is selectively allocated to the target of a saccade.The new findings show that non-goal locations suffer by more than a simple reduction in effective contrast gain.Instead, pre-saccadic modulation of attention reflects the interference between the effective stimuli for the saccadic and perceptual tasks.
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