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Perceiving a discontinuity in motion

Nieman, Dylan and Sheth, Bhavin R. and Shimojo, Shinsuke (2010) Perceiving a discontinuity in motion. Journal of Vision, 10 (6). Art. No. 9. ISSN 1534-7362.

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Studies have shown that the position of a target stimulus is misperceived owing to ongoing motion. Although static forces (fixation, landmarks) affect perceived position, motion remains the overwhelming force driving estimates of position. Motion endpoint estimates biased in the direction of motion are perceptual signatures of motion's dominant role in localization. We sought conditions in which static forces exert the predominant influence over perceived position: stimulus displays for which target position is perceived backward relative to motion. We used a target that moved diagonally with constant speed, abruptly turned 90° and continued at constant speed; observers localized the discontinuity. This yielded a previously undescribed effect, “turn-point shift,” the tendency of observers to estimate the position of orthogonal direction change backward relative to subsequent motion direction. Display and mislocalization direction differ from past studies. Static forces (foveal attraction, repulsion by subsequently occupied spatial positions) were found to be responsible. Delayed turn-point estimates, reconstructed from probing the entire trajectory, shifted the horizontal coordinate forward in the direction of motion. This implies more than one percept of turn-point position. As various estimates of turn-point position arise at different times, under different task demands, the perceptual system does not necessarily resolve conflicts between them.

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Additional Information:© 2010 ARVO. Received May 7, 2009; published June 8, 2010. We are indebted to the volunteers who participated in our experiments. Ritik Tiwari helped conducted several experiments for which we are especially grateful. We would like to thank Saumil Patel for a careful review of an earlier version of the manuscript. We thank Rick Cai and an anonymous reviewer for their detailed and thought-provoking criticisms. Author contributions: DN and BRS contributed equally to the work.
Subject Keywords:motion-2D; spatial vision; eye movements
Issue or Number:6
Record Number:CaltechAUTHORS:20100823-113403146
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Official Citation:Nieman, D., Sheth, B. R., & Shimojo, S. (2010). Perceiving a discontinuity in motion. Journal of Vision, 10(6):9, 1–23,, doi:10.1167/10.6.9.
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:19593
Deposited By: Tony Diaz
Deposited On:23 Aug 2010 19:52
Last Modified:03 Oct 2019 01:59

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