The object of the present dissertation was to examine infants’ abilities to detect unjustified emotions and how this detection influences their selective trust towards unreliable individuals. The focus of the first study was to investigate whether 15- and 18-month-olds react the same way to unjustified (i.e., distress following a positive experience or happiness following a negative experience) and justified (i.e., distress following a negative experience or happiness following a positive experience) emotional reactions. Only 18-month-olds detected the mismatching facial expressions: the unjustified group showed more hypothesis testing across events than the justified group. Older infants in the justified group also showed more concerned reactions to negative expressions than those in the unjustified group. 

The second study examined whether 18-month-olds’ helping behaviors, emotional referencing and imitation are influenced by the reliability of an emoter. Infants exposed to an unjustified emoter did more hypothesis testing and showed less concern towards the actor than those exposed to a justified emoter. During the emotional referencing task, the justified group first opened a container towards which the actor expressed “happiness” rather than “disgust”, while the reverse was true for the unjustified group. As expected, no differences were found between the groups on the instrumental helping and imitation tasks, but the justified group needed fewer prompts to help the actor than the unjustified group when emotional help was requested. 

The third study examined how 18-month-olds react to someone who displays a neutral facial expression following negative experiences. In one condition, infants saw the actor display sadness, while she remained neutral in the other condition. Then, infants interacted with the actor in emotional referencing, instrumental helping, empathic helping, and imitation tasks. Infants in both groups engaged in similar levels of hypothesis testing. However, infants in the sad group expressed more concerned facial expressions towards the actor than those in the neutral group. No differences were found between the two groups on the interactive tasks. 

Taken together, the results from these studies show that 18-month-olds are sensitive to emotions following emotional experiences and that a person’s emotional accuracy modifies infants’ subsequent behaviors towards that person, specifically in the emotional domain.