Summary: Displaced aggression—redirecting frustration onto an uninvolved target—has now been studied in mice, revealing that identity and social history play key roles in shaping aggressive behavior. Male mice primed by seeing a rival behind a barrier showed increased aggression only when the rival was unfamiliar or lacked a clear social hierarchy.
No increase occurred if the instigator was a familiar dominant or subordinate, suggesting that mere frustration doesn’t fully explain the behavior. These findings reveal that aggression in mammals is highly context-dependent and influenced by social recognition and relationship dynamics.
Key Facts:
- Social Context Matters: Mice showed elevated aggression only when instigated by a novel or socially ambiguous rival.
- Not Just Frustration: Aggression did not increase when the instigator had a known dominance relationship, challenging simple frustration models.
- Future Directions: Results lay the foundation for investigating brain circuits behind context-sensitive aggression.
Source: University of Tsukuba
Displaced aggression, such as lashing out at an unrelated individual after a frustrating experience, is a well-documented phenomenon in both humans and animals.
In mice, males typically attack unfamiliar, potentially rival males that enter their territory.
However, when the rival was placed inside a transparent enclosure, physical contact was blocked despite visual and olfactory access.
This situation increased arousal in the subject—a phenomenon known as “social instigation”—which primed the animal for heightened aggression.
When subsequently presented with access to a different rival, the subject exhibited significantly more intense aggression.
To better understand this phenomenon, the research team tested how the identity of the mouse in the transparent enclosure affected the subject’s aggression.
Their findings demonstrated that male mice displayed increased aggression only when the instigator was either a novel individual or one with whom they had no established dominance relationship, even if they were visually familiar.
In contrast, no increase in aggression was observed when the instigator was a familiar opponent with a known hierarchical relationship (either dominant or subordinate).
These results indicate that the heightened aggression observed during instigation was not simply due to frustration from being unable to attack, but rather reflects a context-dependent response influenced by the opponent’s identity and social relationship. The findings highlight the role of social recognition in the regulation of aggressive behavior in mammals.
This study provides critical insights into the cognitive and social factors influencing aggression and lays the groundwork for future investigations into the neural mechanisms underlying aggressive behaviors.
The research team aims to further elucidate the brain functions responsible for context-sensitive aggression in subsequent studies.
Funding:
This study was supported by Japan Science and Technology Agency (JST) FOREST Program Grant Number JPMJFR214A, Japan Society for the Promotion of Science (JSPS) KAKENHI Grant Numbers 22K19744, 22H02660, and a research grant from the Astellas Foundation for Research on Metabolic Disorders.
About this aggression and personality research news
Author: YAMASHINA Naoko
Source: University of Tsukuba
Contact: YAMASHINA Naoko – University of Tsukuba
Image: The image is credited to Neuroscience News
Original Research: Open access.
“Aggression is not blind: dominance and social history modulate murine responses to social instigation” by TAKAHASHI, Aki et al. Psychopharmacology
Abstract
Aggression is not blind: dominance and social history modulate murine responses to social instigation
Rationale
The social instigation procedure is a behavioral model used to induce escalated aggression in male mice. In this procedure, a brief indirect encounter with a novel rival male (instigator) placed in a tube enhances aggression toward an intruder in the subsequent agonistic encounter. However, social factors that drive this pro-aggressive effect remain unclear.
Objectives
This study investigates how social novelty, familiarity, and dominant-subordinate hierarchy influence the pro-aggressive effect of social instigation.
Methods
A male instigator in a perforated tube was placed in the test mouse’s home cage for 5 min, followed by the introduction of an intruder male to assess the test animal’s aggression. Different types of instigators were used to examine the roles of social novelty and dominance hierarchy. Aggressive behavior was compared to baseline aggression without social instigation.
Results
Exposure to a novel male instigator escalated aggression, as indicated by shorter attack latency and increased frequency and duration of aggressive behaviors. In contrast, when a familiar intruder male was presented as the instigator, attack latency was reduced but the total amount of aggressive behaviors remained unchanged. When the instigator had an established dominant-subordinate relationship with the test mouse, aggressive behavior was not enhanced.
However, when a familiar male without a prior dominant-subordinate relationship was used, aggressive behavior increased to levels comparable to those induced by a novel instigator.
Conclusions
Social novelty and an ambiguous social hierarchy of the instigator promote the pro-aggressive effect of social instigation in male mice.
