An automatic valuation system in the human brain: evidence from functional neuroimaging.

According to economic theories, preference for one item over others reveals its rank value on a common scale. Previous studies identified brain regions encoding such values. Here we verify that these regions can valuate various categories of objects and further test whether they still express preferences when attention is diverted to another task. During functional neuroimaging, participants rated either the pleasantness (explicit task) or the age (distractive task) of pictures from different categories (face, house, and painting). After scanning, the same pictures were presented in pairs, and subjects had to choose the one they preferred. We isolated brain regions that reflect both values (pleasantness ratings) and preferences (binary choices). Preferences were encoded whatever the stimulus (face, house, or painting) and task (explicit or distractive). These regions may therefore constitute a brain system that automatically engages in valuating the various components of our environment so as to influence our future choices.