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Observing conspecifics scratching induces a contagion of scratching in Japanese monkeys (Macaca fuscata)
1Department of Social Behaviour, Primate Research Institute, Kyoto University, Aichi, Japan. nakayama@pri.kyoto-u.ac.jp
Abstract:
Although a large number of studies have examined self-directed behaviors (SDBs) such as scratching and self-grooming as nonverbal leakage of negative emotional arousal in humans, few studies have investigated the informative function of SDBs in nonhuman primates. The present study investigated whether viewing another monkey scratching itself elicited negative arousal from conspecific observers in Japanese monkeys (Macaca fuscata). An experimental situation was created in which the target monkey watched a stranger through a small peephole and the observer monkey(s) watched the target in turn. Scratching spread when conspecific observers watched the target scratching itself while performing monitoring behavior. The author proposes that the possible contagion of scratching by monkeys observing another's scratching may involve transmission of a psychological state, a primitive style of empathy.
Insights
In Japanese monkeys, observing another monkey scratch itself can trigger contagious scratching in observers. This suggests a primitive form of empathy may be at play, showing social transmission of arousal.
Area of Science:
- Primate behavior
- Ethology
- Social cognition
Background:
- Self-directed behaviors (SDBs) like scratching are studied as indicators of negative emotional arousal in humans.
- Research on the informative function of SDBs in nonhuman primates is limited.
Purpose of the Study:
- To investigate if observing conspecific scratching elicits negative arousal in Japanese monkeys (Macaca fuscata).
- To explore the potential for contagious scratching as a social signal in primates.
Main Methods:
- An experimental setup was designed where a target monkey observed a stranger.
- Observer monkeys watched the target monkey's behavior through a peephole.
- The occurrence of scratching in observer monkeys was recorded during target monkey scratching and monitoring behaviors.
Main Results:
- Scratching behavior spread among observer monkeys when they watched the target monkey scratching.
- This contagion occurred particularly when observers were engaged in monitoring behavior.
Conclusions:
- Observing conspecific scratching can induce arousal and contagious scratching in Japanese monkeys.
- This phenomenon may indicate a primitive form of empathy or psychological state transmission in primates.
