August 2023
Volume 23, Issue 9
Open Access
Vision Sciences Society Annual Meeting Abstract  |   August 2023
tCFS: A new ‘CFS tracking’ paradigm reveals uniform suppression depth regardless of target complexity or salience
Author Affiliations
  • Jacob Coorey
    The University of Sydney
  • David Alais
    The University of Sydney
  • Randolph Blake
    Vanderbilt University
  • Matthew Davidson
    The University of Sydney
Journal of Vision August 2023, Vol.23, 5819. doi:
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      Jacob Coorey, David Alais, Randolph Blake, Matthew Davidson; tCFS: A new ‘CFS tracking’ paradigm reveals uniform suppression depth regardless of target complexity or salience. Journal of Vision 2023;23(9):5819.

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

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When the eyes view separate, incompatible images, the brain suppresses one image and the other is perceived. This interocular suppression can be prolonged by presenting a dynamic stimulus to one eye, resulting in continuous flash suppression (CFS) of the static image. Measuring how long a suppressed image takes to breakthrough CFS (bCFS) is often used to investigate unconscious processing and has led to controversial claims about visual processing without awareness. Advocates interpret faster bCFS times to salient stimuli as evidence for unconscious high-level processing, while opponents claim differences in low-level stimulus features determine breakthrough times. We address this controversy with a new ‘CFS tracking’ paradigm (tCFS): the initially suppressed image steadily increases in contrast until breaking suppression (indicated by a key press) and then begins decreasing until it again becomes suppressed (indicated by another key press) after which contrast rises again and the cycle continues. Unlike bCFS, tCFS provides contrast thresholds for breakthrough and suppression, with the threshold difference providing a measure of CFS suppression depth. This new tCFS paradigm confirms that: (i) breakthrough thresholds differ across target type (e.g., grating vs face) – as bCFS has shown – but (ii) suppression depth does not vary across target type. Once breakthrough contrast is reached (which varies over stimulus category, likely explained by low-level stimulus factors), all stimuli show a strikingly uniform reduction in the corresponding suppression threshold and thus a constant suppression depth. Uniform suppression depth indicates a single mechanism of CFS suppression, one likely occurring early in visual processing where it is not modulated by image salience or complexity. Results from this new tCFS method disclose that variations in breakthrough thresholds alone do not suffice for drawing inferences about unconscious processing – complementary suppression thresholds are required to preclude potentially misleading conclusions.


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