The facial expression of anger in seven-month-old infants.

This study concerned whether anger can be observed reliably in facial expressions as early as 7 months of age in a sample of 30 infants. It also assessed the influence of several variables on anger responses: infant's familiarity with the frustrator (mother vs. stranger), repetition of trials, and sex of the child. Correlations were obtained between the expression of anger and cognitive developmental level, maternal perceptions of irascibility (temperament), time since eating or sleeping, and facial flushing. Dependent variables included facial expression components as well as ratings of facial flushing. We found that the capacity to express anger is well developed by 7 months of age: facial patterning was detected reliably in the absence of contextual information, and repeated frustrations increased the amount of anger shown. No significant relationships were found, however, between facial expression of anger and temperament, drive states, or cognitive developmental scores.