Research Repository

Smooth pursuit operates over perceived not physical positions of the double-drift stimulus

Maechler, Marvin R and Heller, Nathan H and Lisi, Matteo and Cavanagh, Patrick and Tse, Peter U (2021) 'Smooth pursuit operates over perceived not physical positions of the double-drift stimulus.' Journal of Vision, 21 (11). p. 6. ISSN 1534-7362

[img]
Preview
Text
Smooth pursuit operates over perceived not physical positions of the double-drift stimulus.pdf - Published Version
Available under License Creative Commons Attribution.

Download (749kB) | Preview

Abstract

The double-drift illusion produces a large deviation in perceived direction that strongly dissociates physical position from perceived position. Surprisingly, saccades do not seem to be affected by the illusion (Lisi & Cavanagh, 2015). When targeting a double-drift stimulus, the saccade system is driven by retinal rather than perceived position. Here, using paired double-drift targets, we test whether the smooth pursuit system is driven by perceived or physical position. Participants (n = 7) smoothly pursued the inferred midpoint (Steinbach, 1976) between two horizontally aligned Gabor patches that were separated by 20° and moving on parallel, oblique paths. On the first half of each trial, the Gabors’ internal textures were static while both drifted obliquely downward. On the second half of each trial, while the envelope moved obliquely upward, the internal texture drifted orthogonally to the envelope's motion, producing a large perceived deviation from the downward path even though the upward and downward trajectories always followed the same physical path but in opposite directions. We find that smooth pursuit eye movements accurately followed the nonillusory downward path of the midpoint between the two Gabors, but then followed the illusory rather than the physical trajectory on the upward return. Thus, virtual targets for smooth pursuit are derived from perceived rather than retinal coordinates.

Item Type: Article
Uncontrolled Keywords: illusion; smooth pursuit; motion perception
Divisions: Faculty of Science and Health
Faculty of Science and Health > Psychology, Department of
SWORD Depositor: Elements
Depositing User: Elements
Date Deposited: 26 Nov 2021 15:22
Last Modified: 06 Jan 2022 14:32
URI: http://repository.essex.ac.uk/id/eprint/31424

Actions (login required)

View Item View Item