September 2019
Volume 19, Issue 10
Open Access
Vision Sciences Society Annual Meeting Abstract  |   September 2019
The Symmetry of Deception: Symmetrical Action Influences Awareness by Shifting Event Boundaries
Author Affiliations & Notes
  • Anthony S. Barnhart
    Department of Psychological Science, Carthage College
  • Dillon Krupa
    Department of Psychological Science, Carthage College
  • Cheyenne Duckert
    Department of Psychological Science, Carthage College
Journal of Vision September 2019, Vol.19, 269. doi:
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      Anthony S. Barnhart, Dillon Krupa, Cheyenne Duckert; The Symmetry of Deception: Symmetrical Action Influences Awareness by Shifting Event Boundaries. Journal of Vision 2019;19(10):269.

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

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Many magical deceptions encourage audiences to interpret incomplete information using assumptions constructed from experience with environmental regularities. Symmetry is one such regularity that magicians exploit. Anecdotally, deceptive actions are more likely to evade detection if they are part of a symmetrical action sequence. This symmetry of action has been stressed in a piece of sleight of hand known as the top change, wherein a playing card in one hand is covertly switched for the top card of a deck held in the other hand. If the action underlying the switch is performed with mirror symmetry (i.e., the hand with a single card approaches the deck and then the hand with the deck retreats in the same direction of motion; see Figure 1), the sleight may be harder to detect. We tested this hypothesis across three experiments, varying the symmetrical qualities of viewed action patterns and the viewing behaviors of participants. Participants watched videos of top changes that were symmetrical or asymmetrical, pressing a button upon detecting a switch. Participants were significantly slower to detect sleights in symmetrical conditions than in asymmetrical conditions, but this tendency was not consistent across all forms of symmetry. We suggest that the symmetrical actions are more likely to be grouped together as a single event, whereas the asymmetrical actions are parsed as two separate events (an approach and a retreat). This parsing can influence memory for and attention to details falling near or far from event boundaries. However, differences in perceived intentionality may also drive variability across symmetry conditions.


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