Local enhancement or stimulus enhancement? Bumblebee social learning results in a specific pattern of flower preference

Social learning is a widespread phenomenon allowing animals to use information provided by other animals when presented with a novel situation. A number of recent studies suggest that nonspecific Pavlovian conditioning may explain some forms of social learning, so that animals simply learn to use the presence of conspecifics as a predictor of reward. In this study, we investigated the conditions of flower choice copying behaviour in the bumblebee Bombus terrestris. We raised bumblebees in controlled laboratory conditions to compare the social learning performance of bees with different previous associative experiences. We investigated the influence of foraging experience with conspecifics on transferring the preference for a socially indicated flower type to flowers of the same species not occupied by conspecifics. Observers that had the opportunity to associate conspecifics with rewarding flowers instantly acquired the social flower preference and equally visited occupied and unoccupied flowers of the socially indicated flower type (stimulus enhancement). Such usage of social cues requires prior experience with live conspecifics (bees familiarized only with inanimate model bees did not display the same generalization from socially indicated flowers to other flowers of the same type). By contrast, nonsocial cues and immobile model bees, even if they had been previously associated with rewarding flowers, resulted in a wholly different pattern of preference, where observers preferred only those individual flowers with the nonsocial cue or model bee attached (local enhancement). This difference suggests a special salience of live social cues as information providers and results in different patterns of associative learning than nonsocial cues.