| Summary: | 碩士 === 國立臺灣大學 === 心理學研究所 === 99 === Animals can sense and respond to stimuli signaling danger or threat through observing conspecfics having the same experience, and is denoted as social learning whereby an individual may acquires fear and avoidance responses by observing others. However, there have been few studies on the behavioral or neural mechanisms of socially acquired fear to laboratory aversive stimuli. Here we investigated whether a rat can socially acquire a fear and avoidance response in an inhibitory avoidance task. We tested the effect of observing a conspecific being shocked in three different behavioral paradigms that shared basic procedure but varied in the detail. In the probe phase, rats were given a mild shock to induce an experience of being shocked but not a fear response of its own that was known to facilitate subsequent social learning. In the training phase, the “observer” rat observed a “demonstrator” being shocked in the dark compartment of the inhibitory avoidance apparatus. In the retention test, each rat was reintroduced into the lit part and allowed free exploration in the whole apparatus for 3 min. Its first entrance latency into the dark side and the total time spending in the lit part was recorded. The results showed that after observing a conspecific being shocked, the rats failed to show lengthened entrance latencies but spent more time in the lit part. Furthermore, acquisition of avoidance through social learning was only apparent in the isolation-rearing rats which socially trained with an unfamiliar (never seen each other before) and non-littermate companion. Socially-rearing, familiarity or kinship disrupted the social learning effect. Although the effect of social learning was not as robust as individual learning, our results indicated that rats could acquire some kind of preference via social learning. The social learning experience neither affected the observers’ pain sensitivity of shock nor enhanced subsequent individual learning in a saving paradigm. These data, taken together, suggest that an individual might acquire fear through observation. However, the effect was rather weak and the model needs further improvement to afford studies on the neural mechanism.
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