Can overly positive expectations have negative effects on pain?

We test the effect of a verbal suggestion providing a strong under prediction of the pain intensity of upcoming heat stimuli as compared to a correct prediction and a mild under prediction of the intensity to assess the possible occurrence of contrasts effects (i.e., more intense pain after strong under prediction of pain than after the correct prediction or mild under prediction of pain).

We test the effect of 1) a verbal suggestion providing a strong under prediction of the pain intensity of upcoming heat stimuli as compared to 2) a verbal suggestion providing a correct prediction of the intensity and 3) a verbal suggestion providing a mild under prediction of the intensity to assess the possible occurrence of contrasts effects (i.e., more intense pain after strong under prediction of pain than after the correct prediction or mild under prediction of pain).

In total, 8 heat stimuli of approximately 8 seconds each will be given, all at the same intensity that was found to be moderately to highly painful during calibration.

Primary hypothesis

Participants will experience more intense pain during the first moderately to highly painful stimulus directly after a suggestion of no pain (strong under prediction) as compared to after a suggestion of moderate to high pain (correct prediction) or a suggestion of mild pain (mild under prediction).



Secondary hypothesis

Participants will expect to experience more intense pain during a second heat stimulus when they have experienced moderately to highly intense pain after a suggestion of no pain (strong under prediction) as compared to after a suggestion of moderate to high pain (correct prediction) or a suggestion of mild pain (mild under prediction).



Exploratory

Several additional assessments are done for exploratory analyses, including assessments of expected and experienced pain during each of the other heat stimuli; pain unpleasantness, certainty of the pain expectation, fear of the stimulus, heart rate, and skin conductance for each heat stimulus; trust in the experimenter, state anxiety, and e.g., awareness of the discrepancy between the verbal suggestion and the pain experience after all stimuli; and individual characteristics (e.g., optimism).

Participants take part in one experimental session during which the primary outcome is assessed once after the verbal suggestion. For exploratory purposes, 7 additional heat stimuli of the same intensity are given.

Participants in the experimental condition receive a verbal suggestion stating that the upcoming heat stimuli are expected to be experienced as non-painful (strong under prediction).

Participants in the second condition receive a verbal suggestion stating that the upcoming heat stimuli are expected to be experienced as mildly painful (mild under prediction).

Participants in the control condition receive a verbal suggestion stating that the upcoming heat stimuli are expected to be experienced as moderately to highly painful (correct prediction).