Developments in the expression of affect

The present study is a report of the developmental trends in infants' affect expression from 9 to 21 months, a period that coincided with certain achievements in their language development. Two groups of infants, early and later word learners, were identified according to when they began to say words. At 9 months of age, the two groups did not differ in their frequency of emotional expression nor in the relative amount of time they spent in neutral and positive expression. All of the infants increased their expressivity. However, one group of infants increased their frequency of expression by learning to say words relatively early, whereas the other group increased their frequency of emotional expression and did not learn to say words at the same time.