Gender differences in latency and duration of emotional expression in 7- through 13-month-old infants

A total of 82 infants aged 7 through 13 months were each presented with a randomized order of stimuli in a large descriptive study. All infants passed developmental screening tests (5-minute Apgar and Denver II; Apgar, 1953; Frankenburg & Dodds, 1990). Emotional expressions in response to the stimuli were recorded by video. Male and female infants’ responses to 5 social stimuli (82 x 5 = 410 observations) were analyzed. Latency was the time between the presentation of a stimulus and the beginning of a facial expression in response to that stimulus. Duration was the time between the beginning of a facial expression and the end of that facial expression. Both latency and duration were measured in terms of time (seconds). Gender differences were found in latency: t = 2.41, p < .05, but not duration of emotional expression. Females had shorter latency to emotional expression and longer duration of emotional expression than males.