The habituation instruction focuses on changes of the initial physical fear-responses during exposure sessions. It is explained that the level of anxiety will gradually decrease, or habituate, each time someone faces a feared situation. Participants are then instructed to observe their own level of fear during the three practice trials with the thermode. Together with the experimenter, participants have to indicate their level of arousal on an 11-point scale (0= neutral, 10 = very high) in-between and after the three practice trials. After the practice trial, participants are instructed to reconsider their own development of physical responses. Participants are encouraged to remember the development of their level of arousal during the test trail with the thermode.

The expectation violation instruction focuses on the verification of negative expectancies during exposures sessions. It is explained that exposure exercises help to create own experiences which allow to directly test negative predicted outcomes. Together with the experimenter, participants are then encouraged to formulate concrete concerns in regard to the practice trail with the thermode. Before the practice trails, participants have to indicate the likelihood of their concerns on an 11-point scale (0= not likely, 10 = very likely). After the practice trails, participants are instructed to evaluate their own concerns by some guided questions (e.g. "What did you learn?"). Participants are encouraged to keep their own experience in mind during the test trail with the thermode.

Participants in the control group are not provided with information about exposure therapy. Instead, participants listen to a newspaper article which reports on the daily work in a botanical garden. Together with the experimenter, participants are then asked to name the most interesting aspect in the article. Before the practice trails, participants have to rate how likely it is that they would further inform themselves about botanical gardens on an 11-point scale (0= not likely, 10 = very likely). After the practice trails, participants are provided with some further questions about the newspaper article (e.g. "Did you find the newspaper article interesting?"). This cognitive exercise does not cover any pain-related topics and, therefore, does not serve as a distraction instruction.

Exposure instruction focuses on fear reduction during exposure sessions

Determined by the temperature at which the participant stopped the heat stimulus

Measured on an 11-point scale (0 = no pain; 10 = worst imaginable pain)

Measured on an 11-points scale (0 = bearable; 10 = unbearable)