Hamsters Eavesdrop Too and The Consequent Changes during and after Observational Learning
|Keywords:||觀察學習;社會性訊息襲取;壓力反應;攻擊性;糞便內皮質醇代謝物;倉鼠;observational learning;eavesdropping;stress response;aggression;fecal cortisol metabolites;hamster||Issue Date:||2009||Abstract:||
Observational learning, refers naïve individual acquires new behavior or information via observation of others’ doing, has been demonstrated in a variety of behaviors in different species. Gathering information from social interactions between others is termed eavesdropping which has been studied mainly in humans and certain kinds of fishes and birds, but not in other mammals. Using male golden hamsters and their agonistic behaviors, we developed a behavioral method to study eavesdropping. In this thesis, there are 3 experiments aiming at investigating consequential behavioral and hormonal changes in different groups of observers during and after the observation of two male demonstrators either fighting or encountering neutrally across a 3-day observational learning. In experiment 1, fighting naïve males approach quickly and spent significantly more time investigating the winning demonstrator in the U-maze immediately or one day after the 3-day observation indicating that they are more interested in interacting with the winners rather than the losers. In experiment 2, in contrast to those males in experiment 1, observers previously received one defeated experience from a novel fighter one day before the observational learning displayed completely opposite behavioral patterns (i.e., more defecation, more fleeing behavior and avoidance, and less investigation time toward the winning demonstrator) during the observation of the 3-day aggressive interactions and in the following immediate and long-term U-maze tests whereas such effects did ot appear in the defeated males observed 3-day neutral interactions. These results indicate that the experience of social defeat can effectively influence subsequent behaviors in defeated hamsters. In experiment 3, a non-invasive method was applied to measure the levels of fecal cortisol metabolites (FCM). In experiment 3A, fecal samples were collected every 3 hours and our data indicate that a single fighting experience increased FCM level in the losers 3 hours and 21 hours after the aggressive encounter but has no effect on the winners at any time point. In experiment 3B, a modified 18-hour fecal collection procedure was adopted to analyze those fecal samples collected from observers in experiment 2. During the 3-day observation, these defeated males that observed aggressive interactions defecated more sequentially but their FCM level was relatively decreased compared to those that observed neutral encounters. One day after the last observation, the resultant decrease of FCM level was remained in those high responders that faced the winning demonstrators. Taken together, these results suggest that male hamsters eavesdrop too and the defeated experience significantly affects the ways they use the information and evaluate their potential opponents in subsequent encounter. The information gathered during the observation not only sufficiently affects physical homeostasis but also influences sequential behavioral responses.
|Appears in Collections:||心理學系|
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