A Study on Empathy in Rats: Prosocial Behavior in Active Avoidance Task
Date Issued
2015
Date
2015
Author(s)
Jeng, Chih-Fan
Abstract
Empathy is defined as a kind of cognitive and affective reactions appropriate for someone else’s situation rather than one’s own. This empathic concern of others drives human pro-social behavior, which is defined as voluntary behavior intended to benefit the in-group members. Attempting to replicate prosocial behavior in laboratory animals had encountered difficulty and had been criticized for three involuntary confounding factors: Conditioning, sensitization and social facilitation. Recent studies had found several types of pro-social behavior in rats, but whether they indeed involved empathy was still unclear. We trained rats to learn an active avoidance task (AA) depending on a non-reflexive voluntary act—lever pressing. After AA training, two rats were tested in pairs within two transparent adjacent Skinner boxes. Only one lever in one of two boxes was active to prevent or stop delivery of shock and was accessible only to the better trained rat of the pair. To train rat to acquire the contingency between lever pressing and to rescue the neighbored rat from shock, the procedure started with a lever pressing to avoid or escape of shock for both rats in a yoked condition. At the mean time an intermittent leakage condition was introduced to assess if the rat did learn that a lever pressing rescued the partner. The leakage condition was arranged such that pressing the lever saved only the pressed rat rather than both, rescue of the neighbored rat required a second press of the lever after the self-serving first press. Rats did show a higher rate of second press in the leakage condition than in the yoked condition in which the first press saved both and the second press was a random and meaningless act. In next stage, we examined if the second press behavior in the leakage condition continued if the companion partner was removed from the adjacent box. The results showed that this empathic rescuing response dropped to a chance level after the partner’s removal. We further verified that rats would continue this rescuing behavior even the rescuer was no longer endangered but the rescued rat received signaled or not-signaled shocks, even though the rescuer responded more readily to the responses of the shocked companion rather than the signals predicting the upcoming shock. Further analysis ruled out the possibility that this empathy-like sharing of emotion was confounded by conditioning, sensitization or social facilitation. We proposed that the active rescuing behavior observed in our study meets the three key factors characterized pro-social behavior driven by empathy: (1) intention, (2) knowledge and (3) skills.
Subjects
leakage condition
rescue behavior
social facilitation
sensitization
operant behavior
Type
thesis
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