Go-No-Go task trial structure.

<p>One of four abstract stimuli was presented, followed by a waiting period (+). This, as well as the inter-trial interval, were jittered as shown to aid fMRI analysis. The participant’s decision, either to ‘Go’ or to ‘not Go’, was implemented when the target (o) appeared. The best action was followed by the best outcome 80% of the time. For example, if the second stimulus down was a ‘Go to avoid loss’ one, then quickly pressing the button when the circle appeared would result in a null outcome (yellow horizontal line) 80% of the time, and a loss outcome (downward arrow) 20% of the time. The stimuli were randomized as to their best action and outcome across participants. Before scanning, in the ‘discovery’ version of the task, suboptimal action would attract 20% best outcomes, but during scanning suboptimal action never led to the best outcome. No deception was involved at any point.