August 2023
Volume 23, Issue 9
Open Access
Vision Sciences Society Annual Meeting Abstract  |   August 2023
Distinct rules for binding in position-based and velocity-based motion systems
Author Affiliations & Notes
  • Ilker Duymaz
    Sabanci University, Istanbul, Turkey
  • Nihan Alp
    Sabanci University, Istanbul, Turkey
  • Footnotes
    Acknowledgements  This work is funded by TÜBİTAK 3501 Career Development Grant (220K038).
Journal of Vision August 2023, Vol.23, 5248. doi:
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    • Get Citation

      Ilker Duymaz, Nihan Alp; Distinct rules for binding in position-based and velocity-based motion systems. Journal of Vision 2023;23(9):5248.

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

  • Supplements

Motion perception depends on at least two distinct systems: A velocity-based motion system (VMS) facilitated by early direction-selective cells, and a position-based system (PMS) by tracking objects/features across space and time. However, it is still unclear how these two systems interact to produce coherent motion perception when they work in parallel. Here we investigate how both systems contribute to the perceptual organization of motion cues. To this end, we apply two manipulations to a bistable stimulus, in which eight moving dots could either be perceived as rotating in tandem with their most proximate pair –local motion– or moving around the fixation cross as the corners of two illusory squares –global motion–. The first manipulation systematically disrupts VMS by stroboscopically changing the durations of inter-frame intervals (IFIs: between 0 and 116.69 ms in steps of 16.67). This deactivates the involvement of direction-selective cells, which are known to have short temporal integration windows (<100 ms), undermining VMS. The second manipulation enhances different grouping configurations (locally-grouped, globally-grouped, and no-group) by applying contrast polarity. This allows comparing the effectiveness of the static grouping cues (i.e., proximity and contrast) when only the PMS is active as opposed to when both systems are active. We find that the pattern of bistability changes substantially at IFIs of 33 ms. For IFIs ≥33 ms, perceptual bistability is heavily biased by the static grouping cues. For IFIs <33 ms, perceptual bistability favors the global percept over the local even when the static cues enhance the local grouping, indicating that the contribution of VMS counteracts static grouping cues. These results reveal that distinct rules in VMS and PMS govern the perceptual organization of moving stimuli and that conflicting perceptual configurations between the two systems might explain bistable motion perception.


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