Neural Mechanisms of the Postdecisional Spreading-of-Alternatives Effect: EEG Study

Cognitive dissonance theory suggests that our preferences are modulated by the mere act of choosing. According to the cognitive dissonance theory, a choice between two similarly valued alternatives creates a psychological tension (cognitive dissonance) that is reduced by a post-decisional re-evaluation of the alternatives – the post-decisional spreading-of-alternatives effect – the chosen item being later evaluated more positively and the rejected item more negatively. Previous neuroimaging studies indicated a central role of the medial prefrontal cortex in cognitive dissonance. In this work, we used electroencephalography to investigate a similarity of neural mechanisms underlying postdecisional preference change and general performance monitoring mechanisms. Our study demonstrates that decisions, associated with stronger cognitive dissonance, trigger a stronger negative fronto-central evoked response similar to the error-related negativity (ERN). Furthermore, the amplitude of ERN correlated with the post-decisional spreading-of-alternatives effect. ERN has been previously associated with incorrect responses and a general performance monitoring mechanism. Thus, our results suggest that cognitive dissonance can be reflected in the activity of the medial prefrontal cortex as a part of the general performance-monitoring circuitry