4-month-old infants were specifically selected for patterns of affective and motoric reactivity that were hypothesized to be associated with later inhibited and uninhibited behavior. Infants were classified as high on motor activity and negative affect, high on motor activity and positive affect, or low on motor activity and affect. Brain electrical activity was assessed in these infants at 9 months of age, and behavior toward novelty was observed at 14 months of age. Infants who were high on motor activity and negative affect exhibited greater right frontal EEG activation at 9 months of age and inhibited behavior at 14 months of age. Infants classified as high motor/high positive at 4 months of age exhibited uninhibited behavior at 14 months of age. No relations were found between frontal asymmetry at 9 months of age and inhibited behavior at 14 months of age. However, greater activation in both the left and right frontal hemispheres was associated with higher inhibition scores at 14 months of age. These findings are discussed in terms of the role that affective and physiological reactivity may play in the development of social behavior during toddlerhood.

The pattern of frontal activation as measured by the ongoing electroencephalogram (EEG) may be a marker for individual differences in infant and adult disposition to respond with either positive or negative affect. We studied 48 4-year-old children who were first observed in same-sex quartets during free-play sessions, while making speeches, and during a ticket-sorting task. Social and interactive behaviors were coded from these sessions. Each child was subsequently seen 2 weeks later when EEG was recorded while the child attended to a visual stimulus. The pattern of EEG activation computed from the session was significantly related to the child's behavior in the quartet session. Children who displayed social competence (high degree of social initiations and positive affect) exhibited greater relative left frontal activation, while children who displayed social withdrawal (isolated, onlooking, and unoccupied behavior) during the play session exhibited greater relative right frontal activation. Differences among children in frontal asymmetry were a function of power in the left frontal region. These EEG/behavior findings suggest that resting frontal asymmetry may be a marker for certain temperamental dispositions.

4-month-old infants were specifically selected for patterns of affective and motoric reactivity that were hypothesized to be associated with later inhibited and uninhibited behavior. Infants were classified as high on motor activity and negative affect, high on motor activity and positive affect, or low on motor activity and affect. Brain electrical activity was assessed in these infants at 9 months of age, and behavior toward novelty was observed at 14 months of age. Infants who were high on motor activity and negative affect exhibited greater right frontal EEG activation at 9 months of age and inhibited behavior at 14 months of age. Infants classified as high motor/high positive at 4 months of age exhibited uninhibited behavior at 14 months of age. No relations were found between frontal asymmetry at 9 months of age and inhibited behavior at 14 months of age. However, greater activation in both the left and right frontal hemispheres was associated with higher inhibition scores at 14 months of age. These findings are discussed in terms of the role that affective and physiological reactivity may play in the development of social behavior during toddlerhood.

The pattern of frontal activation as measured by the ongoing electroencephalogram (EEG) may be a marker for individual differences in infant and adult disposition to respond with either positive or negative affect. We studied 48 4-year-old children who were first observed in same-sex quartets during free-play sessions, while making speeches, and during a ticket-sorting task. Social and interactive behaviors were coded from these sessions. Each child was subsequently seen 2 weeks later when EEG was recorded while the child attended to a visual stimulus. The pattern of EEG activation computed from the session was significantly related to the child's behavior in the quartet session. Children who displayed social competence (high degree of social initiations and positive affect) exhibited greater relative left frontal activation, while children who displayed social withdrawal (isolated, onlooking, and unoccupied behavior) during the play session exhibited greater relative right frontal activation. Differences among children in frontal asymmetry were a function of power in the left frontal region. These EEG/behavior findings suggest that resting frontal asymmetry may be a marker for certain temperamental dispositions.

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