In one study, male mice were divided into three groups: fighters, spectators and novice fighters. The mice then took part in three different 10-minute trials over eight days.
The “fighters” fought smaller, weaker mice. The “spectator mice” sat on a raised platform behind a transparent barrier and watched the others fight. The “novice mice” fought a toy mouse but did not see any other fights.
Good at fighting
On the ninth day, all the mice were pitted against a difficult opponent. The mice that had fought real mice were good at fighting, but those that had only watched were almost as good. Those that had faced a toy mouse, however, were less inclined to fight.
Both the fighters and the spectators also spent less time with their backs turned to their opponents. However, the spectators did not attack more, which the researchers interpret as meaning that watching violence did not make them more aggressive.
Changes in the brain
When the researchers examined the mice's brains, they saw that those that had only watched showed changes similar to those in the brains of the fighters.
Another finding in the study, published in Nature, was that the mice did not seem able to tear their eyes away from a fight in progress. Previous studies have shown that the same applies to monkeys and humans.
Because this was a mouse study, the results cannot be directly applied to humans, but the researchers write that the findings may provide clues about how exposure to violent experiences shapes people's responses to threats.
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