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Computerized stimuli for studying oddity effects

Dobbinson, Khia E.; Morrell, Lesley J.; Skarratt, Paul A.


Khia E. Dobbinson


Khia Dobbinson


Visually hunting predators must overcome the challenges that prey groups present. One such challenge is the confusion effect where an overburdened visual system means predators are unable to successfully target prey. A strategy to overcome confusion is the targeting of distinct, or odd, individuals (the oddity effect). In live prey experiments, manipulation of group member phenotypes can be challenging and prey may differ on more than the single feature one intends to define as odd. The use of highly controllable computerized stimuli to study predator-prey interactions is increasingly popular in the field of behavioral ecology. However, to our knowledge, the validity of computerized stimuli to study the oddity effect has not been established.
Predator choice experiments were conducted using naive stickleback predators to ascertain whether the oddity effect could be demonstrated in the absence of live prey.
We found evidence for both the oddity effect and preferential targeting of group edges and low density regions, as would be predicted if predators targeted prey individuals to minimize confusion. The oddity effect was evident at a low threshold, above which dots were no longer perceived as odd, and no longer attacked more often than expected by chance.
We conclude that computerized stimuli are an improved, practical method for studying oddity effects while further validating the use of similar methods for studying other aspects of visual predation. In addition to higher control of ‘prey’ appearance, the replacement of live prey animals with digital stimuli is ethically beneficial and reusing code improves experimental efficiency.


Dobbinson, K. E., Morrell, L. J., & Skarratt, P. A. (2020). Computerized stimuli for studying oddity effects. Behavioral ecology, 31(1), 176-183.

Journal Article Type Article
Acceptance Date Aug 19, 2019
Online Publication Date Oct 16, 2019
Publication Date Jan 31, 2020
Deposit Date Sep 9, 2019
Publicly Available Date Oct 17, 2020
Journal Behavioral Ecology
Print ISSN 1045-2249
Electronic ISSN 1465-7279
Publisher Oxford University Press
Peer Reviewed Peer Reviewed
Volume 31
Issue 1
Pages 176-183
Public URL


Article (336 Kb)

Copyright Statement
©2019 University of Hull

This is a pre-copyedited, author-produced version of an article accepted for publication in Behavioral ecology following peer review. The version of record Morrell, L., Dobbinson, K., & Skarratt, P. Computerized stimuli for studying oddity effects. Behavioral ecology is available online at:

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