Basic features, conjunctive searches, and the confusion effect in predator–prey interactions

  • Colin R. Tosh
  • Jens Krause
  • Graeme D. Ruxton


The confusion effect describes the observed decrease in the likelihood that a predator will successfully catch any prey when attacking larger groups of moving prey. We introduce readers to the work of cognitive psychologists interested in human visual attention who have been studying their own version of the confusion effect for many years, developing methods and concepts that may be of fundamental utility to behavioral ecologists. In psychology, ‘basic features’ are characteristics unique to a target object in the visual field that no distracter objects share. Images containing targets with basic features are often less likely to induce the confusion effect in human subjects. Target objects with conjunctions of features, on the other hand, have no individual characteristics unique from distracters, but unique characteristics in combination. Such targets more often induce the confusion effect in humans. We propose the ‘basic feature’ (vs. conjunctions of features) as a new organizing concept for studies on the occurrence of the confusion effect in nature, potentially allowing predictions about which types of prey groups are likely to induce the confusion effect in predators.


Basic feature Behavioral ecology Cognitive psychology Confusion effect Conjunctions 



This work was funded by the UK Natural Environment Research Council (NERC) grant NE/D010772/1.


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Copyright information

© Springer-Verlag 2008

Authors and Affiliations

  • Colin R. Tosh
    • 1
  • Jens Krause
    • 1
  • Graeme D. Ruxton
    • 2
  1. 1.Institute of Integrative and Comparative Biology, Faculty of Biological SciencesUniversity of LeedsLeedsUK
  2. 2.Division of Environmental and Evolutionary Biology, IBLSUniversity of GlasgowGlasgowUK

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