The Role of Feedback in Visual Processing
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1
University of Illinois, Urbana-Champaign, Psychology, United States of America
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2
University of Illinois, Urbana-Champaign, Beckman Institute, United States of America
We explore the relationship between parietal/attention mechanisms and the feedback implicated in visual masking. We use two masking paradigms that are thought to depend on feedback: metacontrast masking and object substitution masking (OSM). Both are examples of masking in which a mask reduces the visibility of an earlier target. Metacontrast masking occurs even when the target and mask are the only stimuli present, whereas OSM requires the presence of multiple potential targets. This difference suggests that the feedback mechanisms necessary to detect a target in OSM may overlap with those involved in attentional selection, whereas metacontrast masking is less dependent on attention. In line with this idea, we show that priming for a masked stimulus, which is thought to depend on attention, is obtained only during metacontrast masking and not during OSM or during metacontrast with multiple potential targets. These data support the idea that OSM interferes with attention-related feedback mechanisms, whereas metacontrast is less dependent on these particular feedback mechanisms. In a second experiment, we ask whether transcranial magnetic stimulation (TMS) can interfere with feedback and thus stimulus visibility. TMS over occipital lobe elicits phosphenes and shows a similar suppression of visibility as metacontrast masking. TMS over parietal cortex, however, shows no such reduction in visibility despite the fact that it produces similar phosphene experiences and has been shown to evoke activity in ventral visual areas. Together these data suggest that although parietal feedback and attention may impact visual awareness, they are not the only factors at play.
Acknowledgements
NIH NEI R01EY022605
Keywords:
Awareness,
Vision,
TMS,
object substitution masking,
metacontrast masking
Conference:
XII International Conference on Cognitive Neuroscience (ICON-XII), Brisbane, Queensland, Australia, 27 Jul - 31 Jul, 2014.
Presentation Type:
Symposia
Topic:
Cognition and Executive Processes
Citation:
Beck
DM and
Tapia
E
(2015). The Role of Feedback in Visual Processing.
Conference Abstract:
XII International Conference on Cognitive Neuroscience (ICON-XII).
doi: 10.3389/conf.fnhum.2015.217.00413
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Received:
14 Apr 2015;
Published Online:
24 Apr 2015.
*
Correspondence:
Dr. Diane M Beck, University of Illinois, Urbana-Champaign, Psychology, Champaign, Illinois, 61820, United States of America, dmbeck@illinois.edu