Flipbook

2 DO SAFETY BEHAVIORS PRESERVE THREAT BELIEFS? 39 Pupil dilations Pupil size of the left eye was measured during CS presentation with an Eyelink 1000 (SR Research, Mississauga, ON, Canada), a video-based eye tracker sampling at 1000 Hz. Pupil dilation responses to the CS were calculated as the relative growth (proportion) during stimulus presentation from 0 to 5 s after stimulus onset compared to baseline (200 ms before stimulus onset) and the maximum proportional dilation in this window was used for further analysis (cf. Visser et al., 2013). Contingencies and pleasantness After the experimental task, participants indicated whether each CS (i.e., the square, triangle, and circle) was followed by the loud noise on a 3-point Likert scale with the categories never , sometimes , and always as an additional check of contingency awareness. As a manipulation check, participants rated the (un)pleasantness of the loud noise when they had the headphones on and when they had the headphones off on two 100 mm VAS from extremely unpleasant (left, i.e., 0) to extremely pleasant (right, i.e., 100). Finally, they were asked to describe what happened when they unplugged the headphones and when they took off the headphones to assess if they had understood the consequences of the full avoidance response and subtle safety behavior. Procedure Participants were tested individually in a darkened room with dimmed lights. After the informed consent procedure, participants filled out the STAI. They then received oral instructions from the experimenter, followed by written instructions on the computer screen. Participants were told that there was a relationship between the CS and the US, and that they should try to discover this relationship. They were also instructed and demonstrated how to unplug the headphones (full avoidance) and plug them back into the sound amplifier, and how to take off the headphones (subtle safety behavior) and put them back on. Participants were not told what the consequences of these responses were. Next, they were seated with their head in a