Agonistic Bimodal Communication in Domestic Dogs, Canis Familiaris (#506)
Dogs use a variety of visual and acoustic signals during social interactions. Their agonistic vocalisations (growls and barks) have been extensively studied, with research focusing on the vocalisations’ information content and their effects on receivers. However there has been little empirical research on the form and function of visual signals that are simultaneously displayed. As a preliminary investigation on the role of agonistic acoustic and visual signals we aimed to categorize dogs’ bimodal signals according to Partan and Marler’s (1) classification. We presented dogs with unimodal (audio or visual) or bimodal (audio-visual) stimuli and measured their behavioural responses. Behaviours did not qualitatively differ between the bimodal and the two unimodal contexts, indicating that acoustic and visual signals provide redundant information. We could not further classify the signal as ‘equivalent’ or ‘enhancing’ as we found evidence for both subcategories. We also found that dogs were more likely to retreat from the stimulus source when both signals were presented. This pattern is consistent with the hypothesis that agonistic signals function to increase the distance between the signaller and the receiver. As such, we suggest that redundancy in this bimodal signal may enhance signal discriminability by receivers and thus increase receivers’ response accuracy.
- Partan S, Marler P. Communication goes multimodal. Science. 1999;283(5406):1272-3.