To Peck or Not To Peck: The influence of early-life social environment on response inhibition and impulsive aggression in Japanese quails

Deficits in response inhibition (i.e., the ability to suppress inappropriate responses) may contribute to increased impulsive aggression (i.e., unplanned behaviors that harm others). Since early-life environment might influence the development of response inhibition, it could also indirectly affect impulsive aggression. However, this relationship has rarely been directly examined. Here, we investigated whether response inhibition is associated with impulsive aggression and whether this relationship explains the effects of early-life social environments on impulsive aggression in juvenile Japanese quails (Coturnix japonica). Quails (n = 120) were raised in two social conditions: Small groups of five birds or Large groups of 15 birds. Response inhibition was assessed using the Barrier and Cylinder tasks, while impulsive aggression was measured in two contexts - within a group of five familiar individuals and in a dyad with an unfamiliar individual. We found that some aspects of response inhibition were related to impulsive aggression. Furthermore, quails reared in small groups showed significantly poorer response inhibition than those reared in large groups. Yet, impulsive aggression did not significantly differ between the two conditions. These findings suggest that, while impulsive aggression is partly related to response inhibition, other factors mitigate the effects of early social environments on its expression.