Interaction between learning bias and stress as modulator of cognitive flexibility and fear extinction.

In this study, all participants will complete the probabilistic selection task which has been described as measure of trial-and-error procedural learning, and can be used to identify whether one is better at learning from trials that are most likely to be reinforced (also known as a positive learning bias) or from avoiding trials with the least positively reinforced (or most punished) items. Depending on accuracy performance on the above trials, participants will be categorized as either being positive or negative learners. This cognitive task will be administered online (through a platform called Pavlovia) and will last approximately 10 minutes. Following categorization of participants as either positive or negative learners, a group of participants (n=70) will complete a test of cognitive flexibility known as the Wisconsin Card Sorting test. The test will be administed in the lab and lasts approximately 30 minutes. All participants will then be randomly assigned to take part in either the socially evaluated cold pressor test (experimental treatment) or the socially evaluated warm test (control condition). In the former condition, the researcher will be dressed up in a lab coat and will instruct participants to immerge their right hand into ice-cold water (0-4 Celcius; to be measured using a thermemoter before the participant immerges his/her hand) for as long as possible and a maximum duration of 3 minutes. Participants will also be instructed that their facial expression will be recorded for further analysis. Following the stress exposure, a group of participants (n=70) will complete the cognitive flexibility task for a second time, whereas a second group of participants (n=30), will have their electrodermal activity recorded (by attaching two electrodes to the middle and ring finger of a participant) during a fear acquisition and extinction task. In the fear acquisition task, a visual stimulus (CS+) will predict the occurrence of a 95db loud sound (delivered through headphones for 1 second), whereas a second visual stimulus (CS-) will predict the occurrence of a neutral fixation dot. In the fear extinction phase, the CS- will no longer be paired with the loud stimulus. The task lasts 15 minutes.