Comparative aesthetics: A novel approach to investigate multi-modal attractiveness in humans and animals

In our WWTF funded project “Comparative Aesthetics”, we explored commonalities and differences of attractiveness in two species, humans and the ring dove. Physical attractiveness is the subject of intense research in evolutionary biology, psychology, and empirical aesthetics. The historical separation between evolutionary sciences and humanities has so far prevented a unitary approach to study the determinants of attractiveness, both because of little reciprocal interest and the lack of appropriate methods that could be applied in both human and non -human animals. In our project, while acknowledging the strong influence of culture in determining attractiveness in humans, we focused on physical signals as they can be more easily compared across species. In particular, we studied the role of visual and acoustic signals, i.e. faces and voices in humans vs. displays and vocalizations in ring doves, a domesticated bird species. Both humans and doves communicate mostly through the visual and auditory channels, facilitating the comparative approach. We used audio -video stimuli to convey different individuals and manipulated aspects of the visual and auditory information provided. Human participants were asked to rate how attractive they found video stimuli of other humans, while in birds, we used behavioural measures of interest to quantify how attractive female birds found videos of male birds. One of the innovative aspects of our research project is the attempt to tell apart preference from choice when evaluating potential mates. In fact, partner choice is often influenced by factors other than attractiveness, such as familiarity, aggressiveness, dominance, and social structures. We also studied the role of multimodality, that is, the presence of and relationships between both the visual and auditory signals, as we hypothesized that the highest levels of attractiveness required an optimal combination of both types of signals. Our results showed nicely that indeed individuals are more attractive when their visual signals – faces and postural displays – are accompanied by acoustic signals – voices and vocalizations. In humans, we could additionally manipulate the content to be judged by participants and the experimental context. We compared ratings of people speaking a scripted sentence in front of a neutral background to ratings of people speaking about themselves in self -produced videos recorded at home. We found little change between content types in the relationship between attractiveness ratings based on audiovisual vs visual -only and auditory -only. This suggests that the relative contribution of visual and auditory information to first impressions of a person’s attractiveness is quite fixed. We also found only subtle differences in the combined influence of visual and auditory attractiveness for online experiments and real -life speed -dating contexts.