September 2021
Volume 21, Issue 9
Open Access
Vision Sciences Society Annual Meeting Abstract  |   September 2021
Evidence for the McCollough Effect in Primary Visual Cortex
Author Affiliations & Notes
  • Katherine EM Tregillus
    Department of Psychology, University of Minnesota - Twin Cities
  • Karen T Navarro
    Department of Psychology, University of Minnesota - Twin Cities
  • Yanjun Li
    Department of Psychology, University of Minnesota - Twin Cities
  • Stephen A Engel
    Department of Psychology, University of Minnesota - Twin Cities
  • Footnotes
    Acknowledgements  NSF-BCS 1558308, F32 EY031178-01A1
Journal of Vision September 2021, Vol.21, 2814. doi:
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      Katherine EM Tregillus, Karen T Navarro, Yanjun Li, Stephen A Engel; Evidence for the McCollough Effect in Primary Visual Cortex. Journal of Vision 2021;21(9):2814.

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

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Viewing colorful oriented gratings produces color aftereffects that appear in conjunction with a particular orientation. A widely studied example is the McCollough Effect (ME), an illusion characterized by very long-lasting aftereffects. Its neural locus, however, remains mysterious. We used fMRI to investigate this question. Six participants completed 2 scan sessions. In a first, baseline session, participants viewed an array of square wave gratings at 2 orientation pairings (0-deg/90-deg and 45-deg/135-deg) and 2 color pairings (black/white and black/color). The blocks with color were intended to simulate the ME, with contrasts roughly matching the strength of the induced effect. Prior to the second session, we induced the ME with an augmented-reality “McCollough World” method, wherein participants viewed a filtered version of the world through a head-mounted display with an attached camera. Images recorded by the camera were filtered in the Fourier domain to only pass narrowband horizontal or vertical energy, and high-contrast red or green was added. The feed presented to participants switched between color and orientation pairings every 2 sec. (i.e. green/horizontal, red/vertical), and participants viewed videos in this environment for 2 hr. Participants were then immediately scanned using the same paradigm from session 1, with added 3 min. adaptation top-ups between runs. The ME was expected to enhance the color of red/green gratings whose orientation was congruent with it, while in incongruent red/green gratings the ME was expected to cancel their color. We used an atlas-based method to delineate primary visual cortex (V1), and performed multivariate pattern classification of red/green vs black/white on voxels in that region. For 5 of 6 participants, inducing the ME increased the frequency that congruent gratings were classified as red/green, and conversely, increased the frequency that incongruent gratings were labeled as black/white. This pattern provides evidence that the McCollough Effect arises as early as V1.


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