Video playback versus live stimuli to assess quantity discrimination in angelfish (Pterophyllum scalare)

Abstract

Video playback is a widely used technique for presentation of visual stimuli in animal behavior research. In the analysis of behavioral responses to social cues, presentation of video recordings of live conspecifics represents a consistently reproducible stimulus. However, video-recordings do not interact with the experimental subject, and thus this stimulus may be inferior in the social context. Here, we evaluated how angelfish (Pterophyllum scalare) respond to a video playback of conspecifics versus a live shoal of conspecifics. Using binary choice tests, subjects were presented different stimuli. Time spent close to one versus the other stimulus was considered an index of preference. We found angelfish to prefer a live shoal of conspecifics to an empty tank, and also the video playback of a shoal of conspecifics to a blank screen, although the level of preference in the latter was lower than in the former. These results indicate that video-playback of live conspecifics may be appropriate in angelfish, thus allowing manipulation of specific cues that angelfish may use in quantity discrimination. However, when we directly contrasted a live and a video recorded shoal, both having the same number of members, experimental fish preferred the live shoal. When the choice consisted of a live shoal of four conspecifics versus a video playback of a shoal of nine conspecifics no clear preference emerged. These results imply that video-playback has disadvantages in quantity discrimination studies with angelfish. Exploring procedural and/or technological parameters will verify the suitability of video-recording-based stimulus presentation for future use in angelfish.

Behavioral and endocrine responses to noninteractive live and video conspecifics in males of the Siamese fighting fish

“…For example, all studies in fish validating noninteractive video playback compare it with interactive stimuli, not allowing to disentangle the artificial/live component from the interactive/noninteractive component (e.g., Balshine-Earn and Lotem 1998 ). Also, several studies only compare time spent in association with live and video stimuli as a validation measure of video playback (e.g., Clotfelter et al 2006 ; Gómez-Laplaza and Gerlai 2021 ) without controlling for possible cues in video (e.g., motion) that can attract/repel the focal animals, making it difficult to understand if video images are indeed being perceived meaningfully. Further, while behavioral output is usually measured, no study so far has used physiological endpoints to compare the response to video playback and live stimuli in fish.…”