Imagine a situation where one child is teasing another. While the child doing the teasing means it playfully, the other child views it as hostile and responds aggressively. Behavior like this happens all the time with children, but why some react neutrally and others act aggressively is a mystery. The study was published in the Journal of Child Psychology and Psychiatry

In a new study, a University of Iowa-led research team reports it has identified a brain marker associated with aggression in toddlers. In experiments measuring a type of brain wave in 2½ to 3½-year-old children, toddlers who had smaller spikes in the P3 brain wave when confronted with a situational change were more aggressive than children registering larger P3 brain-wave peaks.

Aggressive Behavior

The results could lead to identifying at earlier stage children who are at risk of aggressive behavior and could help stem those impulses before adolescence, an age at which research has shown aggressive behavior is more difficult to treat.

Social Clues

And, when children aren't able to detect a change in social cues, they may be more likely to misinterpret that social cue as hostile rather than playful. Children respond to the same social cues in different ways, and we think it's due to differences in how they interpret that cue, be it neutral or hostile.

The P3 wave is part of a series of brain waves generated when an individual evaluates and responds to a change in the environment such as changed cues in a social interaction. Previous research, primarily in adults, has shown individuals with shorter P3-wave peaks when confronted with a change in the environment tend to be more aggressive. 

As the children watched silent cartoons on a television screen, the pitch of the tones changed, and the researchers measured the P3 brain wave accompanying each change in pitch. The change in pitch is analogous to a change in social interaction, in which the brain consciously or subconsciously reacts to a change in the environment. In this case, it was the change in pitch.

Their brains are less successful at detecting changes in the environment. And, because they're less able to detect a change in the environment, they may be more likely to misinterpret ambiguous social information as hostile, leading them to react aggressively. 

Behavioral Screening

This brain marker has not been widely studied in children and never studied in early childhood about aggression. It might be one of a host of tools that can be used in the future to detect aggression risk that might not show up on a behavioral screening.

The research is important because early interventions are more effective for stemming aggression. Evidence suggests that early interventions and preventive approaches are more effective for reducing aggression than interventions that target aggression later in childhood or adolescence when the behavior is more ingrained and stable.