Multimodal signals are widespread in animal communication. Theoreticians have noted that, from an informational perspective, it is often not clear why multimodal signals should offer any benefit over unimodal complex signals. One possibility is that multimodal signals provide psychological benefits to receivers by virtue of the fact that they stimulate multiple sensory systems. Explicit comparisons of multimodal signals and unimodal complex signals are lacking, however. In this experiment, we examined the behavior of blue jays (Cyanocitta cristata) in a learned signal following task with two-component artificial signals that were either unimodal (visual-visual) or multimodal (visual-acoustic). We also manipulated the reliability of the components to verify that the subjects were able to follow each component type. We compared three measures of receiver performance—proportion of correct responses, learning rate, and reaction time. We found that while our subjects were able to follow both visual and acoustic signal components, performance did not differ in unimodal versus multimodal treatments.
Multimodal Complex signals Multimodal signals Signaling Communication Receivers
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We would like to thank V. Heinen, T. Polnaszek, J. Higham, and an anonymous reviewer for helpful comments on the manuscript, as well as the undergraduates in the Stephens lab, without whom this work would not be possible. We also thank O. Tchernichovski for advising us on the design of the sound attenuation chambers and M. Bee for providing advice and testing equipment. This work was supported by the Alexander and Lydia Anderson Fellowship and the Carol H. and Wayne A. Pletcher Fellowship.
Compliance with ethical standards
Conflict of interest
The authors declare that they have no conflicts of interest.
All housing and experimental procedures were approved by the University of Minnesota Institutional Animal Care and Use Committee (protocol #1109A04421).
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