Others are high strung and reactive, responding with heightened fear to the same startling events. Others fall somewhere in between these two poles. What is surprising is the fact those with the flattest response to evocative images and sounds are the most likely to become violent delinquents in young adulthood.
In a remarkable study, Adrian Raine and his colleagues presented 1,795 three year olds with two different sounds while recording the sweatiness of their palms; the sweatier the palms, the greater the stress and fear. One sound was always associated with a second and highly aversive noise, while the second sound was always played alone. When you pair a neutral sound, such as a pure tone, with a nasty sound, simply hearing the pure tone will make your skin crawl; the pure tone predicts what is coming, and what is coming is not pleasant. When Raine revisited these same individuals twenty years later, those with serious criminal records involving drug abuse, dangerous driving violations, or violence, had the driest palms at the age of three years. In another study, focusing specifically on violence, Raine measured the sweatiness of a different group of three year olds and then looked at their aggressiveness five years later. Once again, those with the driest palms at three years were the most aggressive at eight years. In the absence of a system that enables individuals to learn about danger, the brain and body act as if they were shrouded in an invisibility cloak, blind to the risks of crossing either moral or legal lines.
Raine’s findings fit well with the marshmallow study. In the same way that those who were most impatient in the pre-school years were also most likely to exhibit signs of delinquency in early adulthood, so too were those who were most blasé about fearful stimuli as children most likely to exhibit delinquency in adulthood. Both studies reveal the stability of personality traits. Both studies suggest that at the level of groups of individuals, as opposed to specific individuals, the blasé-impatient types represent a greater threat to our welfare. The point about groups is important. These studies do not allow us to look at an individual’s record and conclude that because he could only wait for 3 seconds before eating the lone marshmallow, and almost fell asleep when presented with loud banging noises, that he is without doubt headed for a life of crime. We also can’t conclude that because patience and reactivity to fearful stimuli can be measured as early as three years old, that these personality traits are entirely genetic and fixed. In fact, other studies carried out by Raine show that if you ramp up the nutrition, exercise, and mental stimulation of children between the ages of 3-5 years, you can reduce adult criminal offenses by 35%. What we can conclude from these findings is that there are significant individual differences that affect who is willing to take risks and who isn’t. We can conclude that there is a strong biological component that constrains the individual’s options. We can conclude that those who start early in life without an understanding of the dangers in the world, act as if they live in a risk-free world. Molecular biologists provide an increasingly precise understanding of how these individual differences start, pointing to genes that bias some individuals to take extreme risks, including the risk of violating social
norms and laws by violently attacking another human being.
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