A recent longitudinal study has linked infant temperament to adult personality, mental health, and social outcomes nearly three decades later.
Temperament refers to individual differences in personality that define how a person reacts to the world around them. These traits are thought to be relatively stable, but there is surprisingly little scientific evidence to support this.
“Researchers have long viewed temperamental qualities as biological predispositions; they are enduring traits that do not simply go away; and they set the foundation for the development of a richer personality. However, few studies have been in the position to show these empirical relations, and no study has examined these relations using temperament in the first year of life,” study authors Alva Tang and associates say.
In a longitudinal study, researchers sought to explore whether behavioral inhibition (BI) — defined as “overly cautious, fearful, and avoidant responses to unfamiliar people, objects, and situations” — in early infancy could predict adult personality and psychological health.
A total of 165 infants were recruited between 1989 and 1993 to take part in a prospective study. At 14 months of age, the infants were observed in several laboratory play sessions and assessed for behavioral inhibition. At 15 years of age, the participants then took part in a flanker task, which tested their response inhibition, while an electroencephalogram (EEG) was recorded. Finally, at 26 years of age, participants completed self-report measures of reserved personality, social functioning, social anxiety, anxiety, and depression. They also reported their history of romantic relationships, their current marital status, and their educational and employment outcomes.
First, results showed that heightened behavioral inhibition at 14 months of age predicted a more reserved personality in adulthood and decreased social functioning with friends and family. Higher BI in infancy was also associated with a history involving fewer romantic relationships but was not related to the likelihood of being married, being in a current relationship, or being parents at age 26. Further, higher BI in infancy predicted internalizing psychopathology (anxiety and depression) in adulthood but did not predict general psychopathology.
To explore individual differences that might lead to increased risk or resilience for future mental health issues, the researchers used the EEG recordings taken at age 15 to measure participants’ error-related negativity (ERN), which reflects the extent that a person is “monitoring their behavior and is sensitive to errors.” It was proposed that ERN might moderate the relationship between early BI and adult psychopathology, potentially explaining why not all children with behavioral inhibition display internalizing issues in adulthood.
Results revealed an interaction between BI and ERN in predicting later internalizing psychopathology, but “only among individuals who showed more negative (larger) amplitudes of the ERN (i.e., < 0.75 SD), but not among those with more positive (smaller) amplitudes.” This finding, the researchers suggest, may be indicative of resilience “since a smaller ERN buffered against risk for internalizing psychopathology among those with higher BI.”
“The reported prospective relation between an inhibited infant temperament and an introverted personality suggests that early temperamental qualities, which influence one’s pattern of emotional, cognitive, and behavioral responses, might become embedded into a larger personality to shape various outcomes,” the authors relate.
The researchers point out that early BI did not appear to affect participants’ romantic relationships or career outcomes in adulthood, which suggests that while infants with heightened behavioral inhibition may be at risk for certain social deficits, “they are by and large able to function effectively in society.”
The study, “Infant behavioral inhibition predicts personality and social outcomes three decades later”, was authored by Alva Tang, Haley Crawford, Santiago Morales, Kathryn A. Degnan, Daniel S. Pine, and Nathan A. Fox.
