Figure 2 | Scientific Reports

Figure 2

From: Causal role of the inferolateral prefrontal cortex in balancing goal-directed and habitual control of behavior

Figure 2

Overview of the Instrumental Learning Task (ILT). Participants were presented with 6 stimulus pairs consisting of fruit pictures. These pictures could serve as discriminative cue stimuli (depicted on top of a closed box) or outcome stimuli (depicted inside an open box). Stimuli pairs were linked by responses, which, if correct, would lead from cue to outcome. (a) Stimuli pairs belonged to one of three discrimination conditions: standard, congruent, and incongruent. In the congruent condition, cue and outcome were identical. In the incongruent discrimination condition, different fruits served as cue and outcome. However, fruits reversed their role as cue and outcome across trials, demanding opposite responses depending on which fruit served as a cue. In the standard discrimination condition, discriminative cue stimuli and outcome stimuli were unique fruits. (b) In the 9-block learning phase, participants were asked to learn the associations between the fruit stimulus pairs and the correct responses by trial-and-error. A correct response led to the outcome fruit and rewarded points. An incorrect response resulted in an empty box and no points. (c) In the outcome devaluation phase, participants were presented with two formerly rewarded outcome fruits associated with opposite responses. However, one fruits was now declared devalued, indicated by a red cross. Participants were asked to press the button that was associated with the still valuable reward. (d) In the 6-block slips-of-action phase, participants were first presented with an overview of all formerly rewarded outcome stimuli at the beginning of each block, two of which were now devalued. Subsequently, they were again presented with the discriminative cue stimuli. Participants were instructed to only show the correct response to cues with still valuable outcomes. If the outcome had been devalued, participants should refrain from responding at all. (e) If participants used the goal-directed system (i.e. S-O-R associations), responses should have been adapted to the actual value of the outcome stimuli. If, however, participants responded habitually (i.e. using S-R associations) they should show responses to stimuli with devalued outcomes (so-called slips-of-action). In this phase, correct responses would earn points whereas slips-of-action would lead to a subtraction of points. Pictures of fruits were taken from free online sources (pixabay.com, openclipart.org and clker.com).

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