Animated images as a tool to study visual communication: a case study in a cooperatively breeding cichlid

Abstract

Investigating the role of visual information in animal communication often involves the experimental presentation of live stimuli, mirrors, dummies, still images, video recordings or computer animations. In recent years computer animations have received increased attention, as this technology allows the presentation of moving stimuli that exhibit a fully standardized behaviour. However, whether simple animated 2D-still images of conspecific and heterospecific stimulus animals can elicit detailed behavioural responses in test animals is unclear thus far. In this study we validate a simple method to generate animated still images using PowerPoint presentations as an experimental tool. We studied context-specific behaviour directed towards conspecifics and heterospecifics, using the cooperatively breeding cichlid Neolamprologus pulcher as model species. N. pulcher did not only differentiate between images of conspecifics, predators and herbivorous fish, but they also showed adequate behavioural responses towards the respective stimulus images as well as towards stimulus individuals of different sizes. Our results indicate that even simple animated still images, which can be produced with minimal technical effort at very low costs, can be used to study detailed behavioural responses towards social and predatory challenges. Thus, this technique opens up intriguing possibilities to manipulate single or multiple visual features of the presented animals by simple digital image-editing and to study their relative importance to the observing fish. We hope to encourage further studies to use animated images as a powerful research tool in behavioural and evolutionary studies.