Figure 1. Experimental design.

A) On Day 1, participants rated the visual complexity of negative and neutral images while fMRI images were collected. The encoding task was followed by a short delay in which we obtained a resting-state scan, removed the participants from the scanner, and administered questionnaires. Then, half of the participants (N=25) completed a cold pressor task in which they submerged their arm in ice-cold water for 3 minutes, and the other half (N=25) completed a control task in which they submerged their arm in lukewarm water for 3 minutes. On Day 2, participants returned for a surprise recognition test, in which they rated whether they recollected the item or, if not, their confidence in whether it was new or old on a 5-point scale. Three saliva samples were obtained: one prior to encoding (S1), one approximately 27 minutes after the stress or control task (S2), and one prior to recognition (S3). B) The plot shows the mean salivary cortisol levels for each sample for the control (violet circles) and stress (green triangles) participants. Following the stress task (S2), stress participants had higher salivary cortisol than control participants. There were no differences before the encoding task (S1) or before the recognition task (S3). Error bars denote standard error of the mean.