Fig 1.
The study consisted of two experimental groups (co-participant group and demonstrator group) and one control group. In the co-participant and demonstrator groups, participants observed a model (presented to the participants as another person taking part in the study or as a coworker of the experimenter, respectively) who rated electrocutaneous stimuli preceded by one of the colors as less painful than those preceded by the other. In the control group, there was no observation phase. In the testing phase, all subjects received 16 pain stimuli of the same individually adjusted intensity.
Table 1.
Descriptive statistics for age, weight, sensation and pain thresholds, and pain ratings—means and standard deviations.
Table 2.
Descriptive statistics for personality variables—means and standard deviations.
Fig 2.
Pain ratings during the testing phase in co-participant group (A), demonstrator group (B) and control group (C). The figure depicts mean pain intensity ratings for stimuli preceded by colorLOW (i.e. the color preceding pain stimuli rated by the model as less painful) and colorHIGH (i.e. the color preceding stimuli rated by the model as more painful) in two experimental groups and preceded by color1 (i.e. blue or orange) and color2 (i.e. orange or blue) in the control group. Abbreviations: NRS–Numeric Rating Scale; SEM–Standard Error of the Mean.
Fig 3.
The magnitude of placebo analgesia.
The figure depicts differences in pain intensity ratings between the co-participant group, demonstrator group and control group. Abbreviations: NRS–Numeric Rating Scale; SEM–Standard Error of the Mean.