Local biases drive, but do not determine, the perception of illusory trajectories

GHEORGHES, Tamara, RICHARDSON, Paul and REIDY, John (2020). Local biases drive, but do not determine, the perception of illusory trajectories. Scientific Reports.

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Official URL: https://www.nature.com/articles/s41598-020-64837-0
Open Access URL: https://www.nature.com/articles/s41598-020-64837-0... (Published version)
Link to published version:: https://doi.org/10.1038/s41598-020-64837-0


When a dot moves horizontally across a set of tilted lines of alternating orientations, the dot appears to be moving up and down along its trajectory. This perceptual phenomenon, known as the slalom illusion, reveals a mismatch between the veridical motion signals and the subjective percept of the motion trajectory, which has not been comprehensively explained. In the present study, we investigated the empirical boundaries of the slalom illusion using psychophysical methods. The phenomenon was found to occur both under conditions of smooth pursuit eye movements and constant fixation, and to be consistently amplified by intermittently occluding the dot trajectory. When the motion direction of the dot was not constant, however, the stimulus display did not elicit the expected illusory percept. These findings confirm that a local bias towards perpendicularity at the intersection points between the dot trajectory and the tilted lines cause the illusion, but also highlight that higher-level cortical processes are involved in interpreting and amplifying the biased local motion signals into a global illusion of trajectory perception.

Item Type: Article
Identification Number: https://doi.org/10.1038/s41598-020-64837-0
SWORD Depositor: Symplectic Elements
Depositing User: Symplectic Elements
Date Deposited: 05 May 2020 12:05
Last Modified: 18 Mar 2021 01:17
URI: https://shura.shu.ac.uk/id/eprint/26233

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