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Expectations developed over multiple timescales facilitate visual search performance

Gekas, Nikos; Seitz, Aaron R.; Seriès, Peggy


Aaron R. Seitz

Peggy Seriès


Our perception of the world is strongly influenced by our expectations, and a question of key importance is how the visual system develops and updates its expectations through interaction with the environment. We used a visual search task to investigate how expectations of different timescales (from the last few trials to hours to long-term statistics of natural scenes) interact to alter perception. We presented human observers with low-contrast white dots at 12 possible locations equally spaced on a circle, and we asked them to simultaneously identify the presence and location of the dots while manipulating their expectations by presenting stimuli at some locations more frequently than others. Our findings suggest that there are strong acuity differences between absolute target locations (e.g., horizontal vs. vertical) and preexisting long-term biases influencing observers' detection and localization performance, respectively. On top of these, subjects quickly learned about the stimulus distribution, which improved their detection performance but caused increased false alarms at the most frequently presented stimulus locations. Recent exposure to a stimulus resulted in significantly improved detection performance and significantly more false alarms but only at locations at which it was more probable that a stimulus would be presented. Our results can be modeled and understood within a Bayesian framework in terms of a near-optimal integration of sensory evidence with rapidly learned statistical priors, which are skewed toward the very recent history of trials and may help understanding the time scale of developing expectations at the neural level.

Journal Article Type Article
Acceptance Date May 31, 2015
Online Publication Date Jul 22, 2015
Publication Date 2015-07
Deposit Date Dec 7, 2021
Journal Journal of Vision
Electronic ISSN 1534-7362
Publisher Association for Research in Vision and Ophthalmology
Peer Reviewed Peer Reviewed
Volume 15
Issue 9
Article Number 10
Public URL