Social dominance modulates eavesdropping in zebrafish

Group living animals may eavesdrop on signalling interactions between conspecifics and integrate it with their own past social experience in order to optimize the use of relevant information from others. However, little is known about this interplay between public (eavesdropped) and private social information. To investigate it, we first manipulated the dominance status of bystander zebrafish. Next, we either allowed or prevented bystanders from observing a fight. Finally, we assessed their behaviour towards the winners and losers of the interaction, using a custom-made video-tracking system and directional analysis. We found that only dominant bystanders who had seen the fight revealed a significant increase in directional focus (a measure of attention) towards the losers of the fights. Furthermore, our results indicate that information about the fighters' acquired status was collected from the signalling interaction itself and not from post-interaction status cues, which implies the existence of individual recognition in zebrafish. Thus, we show for the first time that zebrafish, a highly social model organism, eavesdrop on conspecific agonistic interactions and that this process is modulated by the eavesdroppers' dominance status. We suggest that this type of integration of public and private information may be ubiquitous in social learning processes.

Fluency and attitudes

The goal of this article is to review how, when, and why f luency, or processing ease, affects attitudes. The current article first defines f luency and then discusses its direct impact on attitudes, noting that f luency usually makes attitudes more positive and that it does so for a wide array of attitude objects. Mechanisms and moderators of these direct effects are also described. The article then summarizes how f luency can affect attitudes indirectly, through its impact on other judgments (like perceptions of confidence or truth) and on cognitive operations (like information processing). The article ends by highlighting a few areas where additional research is likely to reap impressive benefits.