Description of the two gambling tasks.

<p>A) Wheel of Fortune (WOF): the subject (with SCR recorded) has to choose between two possible lotteries with different risk and earning possibilities. The subject was asked to choose one of the two wheels by pressing a left or a right button (choice period). A spinning arrow then appeared at the center of the wheel, spins for a variable duration (wait period), and stopped revealing the outcome(s) (feedback period). In the partial feedback condition (30 trials) the subject does not know the outcome of the other lottery; in the complete feedback condition (30 trials) both outcomes are presented. At the end of each trial, subjects had to indicate their affective state using a rating scale. B) Cambridge gambling task (CGT): the subject has to bet points on a choice associated with a given level of risk. Trials are run in blocks (two sets of four blocks), each containing nine trials. A row of ten boxes (red or blue, with a ratio varying across trials) is presented at the top of the screen. Participants are told that a yellow token was hidden in one of the boxes. They then have to guess whether it is in a red or blue box (color). Then they decide how many of their points they wanted to gamble on their choice (point choice) by pressing when they choose: available bets (5, 25, 75, 95 and total) are presented on the right of the screen in a ascending or descending sequence. Then feedback is given about gain or loss and total ongoing fortune (left).