Run this study by downloading the folder and dragging/dropping RLwrapper.m function on the Matlab command window. Psychtoolbox is a requirement.
Upon prompt: Enter subject ID and then indicate which session (test or re-test) it is.
Each run took around 5 minutes to complete and consisted of 56 trials. Inter-trial intervals were randomly drawn from a normal distribution centered around a mean of 1 s. for the training run.
On each run, two unique stimulus pairs, consisting of two symbols were presented.
The side of the screen each stimulus was presented was randomized across trials.
Participants learned to choose one of two stimuli based on the probabilistic
feedback presented on each trial. They were instructed to press a key corresponding
to the side of the stimulus pair they believed to be 'correct' that maximized their
total rewards and make their decisions as accurately and as quickly as possible.
Visual feedback was provided following each choice. Each stimulus pair stayed on
the screen for a maximum of 2,5 s., or until the participants made a response.
At the choice onset, participant's choice was highlighted by keeping the
the selected stimulus on the screen alone for 300 ms.
There were two trial types: Gain and Loss trials. Gain and Loss trials were presented in an interleaved order. The order of Gain and Loss trials were randomized. Two unique and distinct stimulus pairs were associated with each trial type and each stimulus pair was unique to each run. For both trial types, the correct stimulus led to positive feedback 75% of the time, while the incorrect stimulus led to negative feedback on these trials. During positive feedback in Gain trials, the image of a €10 note bill was presented in the middle of the screen under a "+ €10" text printed in color green. During the negative feedback in Gain trials, the image of an empty grey rectangle was presented under a "€0" text printed in color red. For the Loss trials, the positive feedback corresponded to the same screen as the negative feedback during Gain trials, signifying that participants did not incur a monetary loss. During negative feedback in Loss trials, the image of a €10 note bill was crossed out in color red under a "- €10" text printed in red. Feedback images stayed on the screen for 1 s. for all feedback types.