Fig. 1: Behavioral tasks.
a Visit 1. During the scanning session (left), participants performed the valuation task (likeability rating) on half the items and an orthogonal task (age rating for faces and size rating for objects) on the other half. Each of the four blocks comprised 84 items in a randomized order. The order of the four blocks was randomized as well. After the scanning session (right), participants performed a series of 336 choices between two stimuli of the same category. Faces were paired by gender. Objects were paired such that the prices of the two items was approximatively matched. b Visit 2. The second visit took place around 4 weeks later and involved no scanning. Participants performed first the valuation task, augmented with a second-order rating (of how confident they were in their likeability rating), on all the items. Then, they were required to make the same series of choices as in the first visit, in the same order.
