30-year study by University of Maryland researchers found that babies who showed shyness were more likely to become reserved and introverted adults, while those who also showed sensitivity to making errors as teens were more likely to have depression and anxiety in adulthood.
The study was initiated by College of Education Distinguished University Professor Nathan A. Fox. The findings of the study’s current phase, led by postdoctoral fellow Alva Tang, provides the strongest and earliest evidence of a lasting link between infant temperament and adult personality, including social and mental health status. The findings were published this week in the Proceedings of the National Academy of Science.
“Our research helps show that there is continuity between early temperament and adult personality,” Tang said.
The study, funded by the National Institutes of Health, began with more than 150 infants and their families who were recruited at 4 months of age from the Washington, D.C. area. At 14 months, the babies were exposed to unfamiliar situations, like a robot toy or an unfamiliar adult, and those who were very distressed by novel stimuli were labeled “behaviorally inhibited.”
The term applies to about 15-20% of infants and remains relatively stable across toddlerhood and childhood. Children with inhibited temperaments have been found to be at greater risk for developing social withdrawal and anxiety disorders.
While two other studies have followed inhibited children from early childhood to adulthood, this one, conducted by researchers at UMD, the Catholic University of America and the National Institute of Mental Health, started when the subjects were younger. Over the years, the subjects were brought to the lab at University of Maryland for testing, sent questionnaires and underwent functional brain imaging, all to chart the influence of infant temperament on the developing personality of the child, adolescent and young adult.
At age 15, for example, participants had their electrophysiological activity measured, using EEG, during a computerized task. At age 26, participants were assessed for psychopathology, personality traits and levels of social functioning with friends, family and romantic partners, as well as education and employment outcomes.
Adolescents who were more sensitive to making errors, called error-related negativity (ERN), were more likely to exhibit internalizing psychopathology, including anxiety and depression, at age 26.
“As we get older, we develop more and more the ability to monitor our behavior and to identify when we’ve made a mistake,” Fox said. “There’s an error monitoring system in the brain, and it just so happens that behaviorally inhibited kids are sensitive to and vigilant about the environment and their performance. They show exaggerated brain responses when they detect an error compared to non-inhibited children or adolescents.”
The researchers also found that behavioral inhibition at 14 months predicted fewer romantic relationships in the past 10 years at age 26, along with a more reserved personality and lower social functioning with friends and family.