Observing Conspecifics Scratching Induces a Contagion of Scratching in Japanese Monkeys (Macaca fuscata).

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.

Monkey See, Monkey Do: Contagious Itch in Nonhuman Primates

“…or observes another individual performing an action (10,11). Another experiment used unfamiliar monkeys and observed their response to conspecific scratching (12). When one target monkey watched an unfamiliar monkey through a peephole, there was increased probability that an observer monkey would scratch after watching the target monkey perform scratching behavior.…”

Contagious scratching: shared feelings but not shared body locations

“…The fact that the anterior insula (involved in affect and interoception) was the only part of the brain to show a sustained response across the duration of the movies depicting itch is consistent with this. Furthermore, non-human primates, who are also susceptible to contagious itch (Nakayama, 2004), show the same pattern of scratching body parts different to the ones observed (Feneran et al, 2013) However, the vicarious perception of itch appears to differ from comparable findings of vicarious experiences of pain (Osborn and Derbyshire, 2010) or touch (Banissy et al, 2009) in response to seeing pain and touch. In both of these cases, there is a direct correspondence between the body observed and the location of vicarious experience (i.e., seeing touch to the arm is felt on the arm), at least in normal-bodied individuals (i.e., non-amputees).…”

Emotional communication in primates: implications for neurobiology

“…This type of emotional awareness functions to coordinate activity among group members, facilitate social cohesion and motivate conciliatory tendencies, and is likely to play a key role in coordinating social behaviors in largebrained social primates, such as Homonoids. There is evidence in the animal world for contagious yawning, scratching and emotional behavior, including play and aggression [28][29][30].…”