The importance of syntax in a dynamic visual signal: recognition of jacky dragon displays depends upon sequence
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It is well established that recognition of complex acoustic signals, such as bird song, is dependent upon the temporal ordering of signal units or syntax. Much less is known about functionally analogous visual displays. The jacky dragon (Amphibolurus muricatus) is a native Australian agamid lizard with a highly stereotyped visual display made up of three discrete motor patterns. We conducted a playback experiment using high-resolution computer animations of conspecifics to test the importance of temporal order for signal efficacy. Lizards were shown three different life-sized simulated animations of conspecific differing in their skin texture and morphology signatures ranging from highly natural to abnormal. We evaluated signal recognition and assessed the relative importance of syntax and morphology. Our results showed that signal recognition is highly sensitive to syntax and this largely determines the observers’ behavioural responses. Stimuli with abnormal texture and shape were highly effective, as long as the natural order of motor patterns was preserved. Display recognition in jacky lizards hence depends upon syntax in just the same way as temporally constrained signals in other modalities.
KeywordsJacky dragon Amphibolurus muricatus Syntax Morphology Visual display Computer animation
KLW was supported by the Macquarie University Centre for the Integrative Study of Animal Behaviour Postgraduate Research Scholarship, Australian Research Council (project no. DP0345643) and SUNY Empire State College Faculty Development Award. GR was supported by a postdoctoral fellowship from the Institute of Marine Research and by the Norwegian Research Council (grant 204229/F20). Permission to conduct the study was granted by the New South Wales National Parks and Wildlife Services (S11024) and the Macquarie University Animal Ethics Committee (protocol no. 2006/012).
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