ABSTRACT
Research on infants' emotional reactivity generally has focused on the intensity and duration of negative reactions to stimuli measured globally. Few investigations have considered individual differences in the expression of specific emotions (i.e., anger, distress, fear) during stressful situations. In one study, Izard and associates (1995) found that infants' expressions of interest, joy, sadness and anger were present by
2.5 months of age and their rate of occurrence was relatively stable over the first 9 months. Izard, Hembree and Huebner (1987) also demonstrated individual variation in emotional expression in response to inoculations as well as changes in emotional expression to the same stimuli over time. Whereas the predominant response to inoculation in young infants was pain/distress, by 19 months of age, the primary expression had changed to anger. Infant responses to less aversive stimuli (such as frustration) also have been investigated (Lewis, Alessandri, & Sullivan, 1990; Stenberg, Campos, & Emde, 1983). Lewis, Sullivan, Ramsay, and Alessandri (1992) examined facial expressions during a contingency task and observed differential outcomes for anger and sad expressions to extinction. Studies also have shown that individual differences in the patterning of responses to negative stimuli appear to have important consequences for children's development (Cole, Zahn-Waxler & Smith, 1994; Eisenberg, Fabes, Nyman, Bernzweig, & Piñuelas, 1994; Fabes & Eisenberg, 1992; Stifter, Spinrad, & Braungart-Rieker, 1999). Taken together, the evidence suggests that it is important to consider specific indices of emotional reactivity (such as facial expressions) rather than rely on more global measures. In the present study, infants' facial expressions of emotion in response to mildly frustrating stimuli were observed longitudinally at 5 and 10 months of age with the goal of examining patterns in their responses to frustration over time.
