Individual differences in emotionality in infancy.

In this multimethod investigation of early emotionality, we observed 112 8- to 10-month-olds' responses to standard procedures consisting of multiple brief episodes that elicited joy, fear, anger, and discomfort to aversive stimulation. We obtained parental reports about the infants' temperament and observed their emotional tone during naturalistic interactions with their mothers. Parameters of emotional response to the standard procedures (latency, discrete behaviors, and average and peak intensity across facial, vocal, and bodily channels) cohered strongly within each episode. To a lesser extent and with the exception of anger, they also cohered across episodes targeting the same emotion. The four emotions appeared orthogonal, except for the peak intensity of response, which cohered modestly across the 3 negative emotions. The emotionality measures converged to some extent: responses to the standard procedures and father-reported temperament related meaningfully to the infant's emotional tone in mother-child interactions. As predicted, infants' capacity for focused or effortful attention was modestly associated with better modulated negative emotionality.