Schematic illustrating the session and trial definitions for the assessment of Fear Acquisition, Extinction Training, and test for extinction Recall in IOP participants at pre- (Trauma Exposed Psychiatric Controls, TEPC, and PTSD + groups) and post-treatment time points (PTSD + group only). The fear acquisition session contained a CS Habituation block and three Acquisition blocks. In the Acquisition blocks, there were 12 CSs (colored shapes) reinforced on 100% of the trials paired with the US (CS+), 12 colored shapes that were not reinforced (CS-), and 12 trials of the sound probe presented without a CS (noise alone, NA). CS+ = conditioned stimulus reinforced with airblast unconditioned stimulus (US); CS-= conditioned stimulus not paired with US; NA = noise alone (baseline). Created with Biorender.com.