Optimistic people are all alike: Shared neural representations supporting episodic future thinking among optimistic individuals.

Optimism is a critical personality trait that influences future-oriented cognition by emphasizing positive future outcomes and deemphasizing negative outcomes. How does the brain represent idiosyncratic differences in episodic future thinking that are modulated by optimism? In two functional MRI (fMRI) studies, participants were scanned during an episodic future thinking task in which they were presented with a series of episodic scenarios with different emotional valence and prompted to imagine themself (or their partner) in the situation. Intersubject representational similarity analysis revealed that more optimistic individuals had similar neural representations in the medial prefrontal cortex (MPFC), while less optimistic individuals exhibited more idiosyncratic neural representations in the MPFC. Additionally, individual difference multidimensional scaling of MPFC activity revealed that the referential target and emotional valence of imagined events were clearly mapped onto different dimensions. Notably, the weights along the emotional dimension were closely linked to the optimism scores of participants, suggesting that optimistic individuals imagine positive events as more distinct from negative events. These results suggest that shared neural processing of the MPFC among optimistic individuals supports episodic future thinking that facilitates psychological differentiation between positive and negative future events.