December 2022
Volume 22, Issue 14
Open Access
Vision Sciences Society Annual Meeting Abstract  |   December 2022
Strap in for a bumpy ride: pursuit of non-rigid motion
Author Affiliations & Notes
  • Krischan Koerfer
    University of Muenster
  • Tamara Watson
    Western Sydney University
  • Markus Lappe
    University of Muenster
  • Footnotes
    Acknowledgements  This work was supported by the German Research Foundation (DFG La 952-7) and has received funding from the European Union's Horizon 2020 research and innovation programme under the Marie Skodowska-Curie grant agreement No 734227.
Journal of Vision December 2022, Vol.22, 3617. doi:
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      Krischan Koerfer, Tamara Watson, Markus Lappe; Strap in for a bumpy ride: pursuit of non-rigid motion. Journal of Vision 2022;22(14):3617.

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      © ARVO (1962-2015); The Authors (2016-present)

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Non-rigid motion of water, fire, flocks of birds etc. is omnipresent in our world. Last year we reported that one key-component of non-rigid motion, the movement of a visual motion pattern, is already sufficient for accurate motion perception. In natural conditions, visual perception is intermingled with eye movements. Here we report the impact of pursuit and saccades on non-rigid motion perception. Each single frame of our non-rigid motion stimulus consisted of a random dot distribution devoid of structural information. Across frames, dots within a circular area were rotated around the area's center, forming a motion pattern. Independent from the first-order motion within it, the motion pattern itself was then moved across the screen. Participants were asked to pursue the motion pattern. Smooth pursuit gain was very low and compensated by frequent catch-up saccades. Interestingly, participants reported that the pattern appeared to jump during pursuit. We asked participants to adjust a positional shift of the pattern triggered by their catch-up saccades until they perceived the movement of the pattern as smooth. Adjustment data indicated that participants perceived the movement as smooth when the pattern jumped backward by a sizeable proportion of the saccade amplitude. To control that saccades were not a byproduct but the cause of the percept, in a fixation task we replayed individually simulated stimulus movements as recorded during the pursuit trials. Here, participants corrected their former chosen jump amplitude to an amplitude close to zero. We also conducted a series of direction discrimination tasks with varying stimulus duration. Findings showed that non-rigid motion processing takes longer than rigid motion processing and that saccades starting from fixation did not induce a jump percept. We conclude that only catch-up saccades during attempted pursuit induce the jump percept.


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