Fig. 1.

Structural differences between two typical tasks used to investigate appetitive processing in addiction. a) A guessing task adapted from Yacubian et al. (2006), and used by van Holst et al. (2012) in the study of pathological gamblers. On each trial, participants were presented with a representation of the chances (30% or 70%) and amounts (€1 or €5) that they could win or lose. Subjects indicated whether they expected to win or lose with a button press. This was followed by a 4 second anticipation period followed by the trial outcome. A win occurred when a red ace was within the highlighted area. b) A monetary incentive delay task adapted from Knutson et al. (2001) used by Balodis et al. (2012). On each trial, participants were presented with the amount they could win or lose (the first anticipation, A1, phase). During the second anticipation (A2) phase, the participants pressed a button when a target appeared. If the response was quick enough, they won, or avoided losing, the cued amount, with titration of the reaction time to ensure participants were correct on 66% of trials.