Crucial for goal-directed behavior is the capacity to suppress impulses and predominant behavioral responses, called inhibitory control (IC). This ability emerges in early childhood, and a distinction according to neutral ('cold') and emotional ('hot') contexts has been suggested. Here, we ask which maturational changes in the child's brain underlie the emergence of this critical ability. We relate behavioral changes in 3-and 4-year-olds' 'hot' and 'cold' IC to brain maturation, using a multimodal approach that combines cortical and subcortical grey matter structure with white matter connectivity. Our results show that the maturation of distinct parts of the cognitive control brain network support early development of the different IC domains: Whereas 'cold' IC is related to frontoparietal regions and the left thalamus, 'hot' IC is associated with the left supramarginal gyrus and right thalamus. This dissociation of brain networks involved in 'cold' and 'hot' IC is confirmed by independent patterns of thalamocortical connectivity, supporting that IC in neutral and emotional settings relies on independent processes.

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 our choices were blind and we could not have had any previous preference for the option we chose. These blind choice-induced preferences are thought toresult 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.