Anger, sad, and blended expressions to contingency disruption in young infants.

Three studies elicited young infants' (aged 17-23 weeks) anger and sad facial expressions during brief contingency disruptions to explore their potential organization over time as a biphasic process. Study 1 examined partial correlations among anger, sad, blended anger/sad, and neutral expressions during extinction in three extant, independently recruited samples. Across samples, all three negative expressions were inversely related to neutral expressions, but anger and sad expressions were not significantly correlated when anger/sad blends were controlled. Study 2 compared expressions during contingency and disruption minutes in two groups: one in which the disruption was an extinction phase (the absence of the formerly contingent event), or one in which the disruption was noncontingent presentations of the stimuli. Study 3 examined expression trajectories over time in two contingency and extinction sessions. Independent trajectories of anger and sad expressions occurred over time in Studies 2 and 3. Extinction and noncontingency differed in sad expression. The relation between expressions and blends also varied over time.