Cognitive dissonance from 2 years of age: Toddlers', but not infants', blind choices induce preferences.

As adults, not only do we choose what we prefer, we also tend to adapt our preferences according to our previous choices. We do this even when choosing blindly and we could not have had any previous preference for the option we chose. These blind choice-induced preferences are thought to result from cognitive dissonance as an effort to reconcile our choices and values. In the present preregistered study, we asked when this phenomenon develops. We reasoned that cognitive dissonance may emerge around 2 years of age in connection with the development of children's self-concept. We presented N = 200 children aged 16 to 36 months with a blind choice between two toys, and then tested whether their choice had induced a preference for the chosen, and a devaluation of the discarded, toy. Indeed, children's choice-induced preferences substantially increased with age. 26- to 36-months-old children preferred a neutral over the previously blindly discarded toy, but the previously chosen over the neutral toy, in line with cognitive dissonance predictions. Younger infants showed evidence against such blind choice-induced preferences, indicating its emergence around 2 years of age. Contrary to our hypotheses, the emergence of blind choice-induced preferences was not related to measures of self-concept development in the second year of life. Our results suggest that cognitive dissonance develops around 2 years. We speculate about cognitive mechanisms that underlie this development, including later-developing aspects of the self-concept and increasingly abstract representational abilities.