Expecting the unexpected: Temporal expectation increases the flash-grab effect

Kate M. Coffey* (Corresponding Author), Nika Adamian, Tessel Blom, Elle van Heusden, Patrick Cavanagh, Hinze Hogendoorn

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

3 Citations (Scopus)
5 Downloads (Pure)


In the flash-grab effect, when a disk is flashed on a moving background at the moment it reverses direction, the perceived location of the disk is strongly displaced in the direction of the motion that follows the reversal. Here, we ask whether increased expectation of the reversal reduces its effect on the motion-induced shift, as suggested by predictive coding models with first order predictions. Across four experiments we find that when the reversal is expected, the illusion gets stronger, not weaker. We rule out accumulating motion adaptation as a contributing factor. The pattern of results cannot be accounted for by first-order predictions of location. Instead, it appears that second-order predictions of event timing play a role. Specifically, we conclude that temporal expectation causes a transient increase in temporal attention, boosting the strength of the motion signal and thereby increasing the strength of the illusion.
Original languageEnglish
Article number9
Number of pages14
JournalJournal of Vision
Issue number13
Early online date12 Nov 2019
Publication statusPublished - Nov 2019

Bibliographical note

EvH, TB, KC, and HH were supported by the Australian Government through the Australian Research Council's Discovery Projects funding scheme (project DP180102268). PC was supported by grants from Dartmouth College and from Natural Sciences and Engineering Research Council Canada.


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