Emotional Information in Vocalizations of Young Infants

Abstract

The developmental aspects four an infants' adility to express emotions through vocalizations were studied based on perceptual rating experiments involving nine vocalization-and emotion-related reference words. Perceptual rating scores for 200 voice samples recorded from four infants at 2 months of age were compared to those for 517 voice samples recorded from six infants at 6, 9, 12 and 17 months of age. Three factors representing emotional contrast—between crying/frightened/sad and laughing/pleased/happy; between shouting/surprised and whispering/calm; and between speaking and singing-were extracted by factor analysis. Even at 2 months of age, there were significant individual differences in the extracted factor scores, although there was less variability compared to scores obtained from the elder infants. These results may indicate that infants even at 2 months of age can express some emotional contrast through vocalization.