Conspicuousness of distasteful prey affects the strength and durability of one-trial avoidance learning

Previous work has shown that domestic chicks learn more effectively to avoid distasteful prey if the prey in question is conspicuously coloured. However, it is not known whether conspicuousness affects strength of learning directly, or whether differences in learning stem from differences in initial encounter rate (conspicuous prey being detected more easily and hence ingested more frequently by a naive predator). In three experiments using a one-trial avoidance learning procedure in which chicks were allowed a single exposure to red or white distasteful beads on a red or white background, avoidance learning was stronger when the ‘prey’ was conspicuous (contrasted with the background) than when it was cryptic (matched the background). Learned avoidance of a conspicuously coloured bead also persisted, for longer than learned avoidance of a cryptically coloured bead. Thus, conspicuousness directly affected both the strength of initial learning and the duration of memory for a noxious stimulus.