Infants who sweat less in response to scary situations at
age one show more physical and verbal aggression at age three, according to new
research published in Psychological
Science, a journal of the Association for Psychological Science.
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.
How the study was
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 revealed that one year-old infants with lower SCA
at rest and during the robot encounter were more physically and verbally
aggressive at age three.
Interestingly, 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.
These findings suggest that while a physiological measure
(SCA) taken in infancy predicts aggression, mothers’ observations do not.
“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 notes.
What the findings
At the same time, this research has important implications
for intervention strategies:
“These findings show that it is possible to identify at-risk
children long before problematic behaviour is readily observable,” van Goozen
concludes. “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
Co-authors on this research include Erika Baker, Katherine
Shelton, Eugenia Baibazarova, and Dale Hay of Cardiff University.
This research was supported by studentships from the School
of Psychology, Cardiff University, and by a grant from the Medical Research