Infants who sweat less may become more aggressive

Infants who sweat less in response to scary situations at age one show more physical and verbal aggression when they reach the age of three, according to new research.
Lower levels of sweat, as measured by skin conductance activity (SCA), have been linked with conduct disorder and aggressive behaviour in children and adolescents.
Researchers hypothesise that aggressive children may not experience as strong of an emotional response to fearful situations as their less aggressive peers do; because they have a weaker fear response, they are more likely to engage in antisocial behaviour.
Psychological scientist Stephanie van Goozen of Cardiff University and colleagues wanted to know whether the link between low SCA and aggressive behaviours could be observed even as early as infancy.

To investigate this, the researchers attached recording electrodes to infants' feet at age one and measured their skin conductance at rest, in response to loud noises, and after encountering a scary remote-controlled robot.
They also collected data on their aggressive behaviours at age three, as rated by the infants' mothers.

The results showed that one-year-old infants with lower SCA at rest and during the robot encounter were more physically and verbally aggressive at age 3.
Researchers found that SCA was the only factor in the study that predicted later aggression. The other measures taken at infancy - mothers' reports of their infants' temperament, for instance - did not predict aggression two years later.

"This runs counter to what many developmental psychologists would expect, namely that a mother is the best source of information about her child," van Goozen noted.
"These findings show that it is possible to identify at-risk children long before problematic behaviour is readily observable.
"Identifying precursors of disorder in the context of typical development can inform the implementation of effective prevention programs and ultimately reduce the psychological and economic costs of antisocial behaviour to society."
The study was published in journal Psychological Science, a journal of the Association for Psychological Science.