Are people emotionally aroused by hypothetical medical scenarios in experiments? An eye tracking study with pupil dilation

Background: Many studies on the communication of medical risks use hypothetical medical scenarios. The results of these scenarios should have sufficient predictive accuracy to be generalized to real life; thus, it is important to know whether hypothetical medical scenarios work and whether there is a relationship between risk level and emotional arousal. Methods: In an eye tracking experiment (N = 67), we investigated the influence of a simple hypothetical medical scenario on pupil dilation, a measure of emotional arousal. In this medical scenario, the participants were shown three risk levels (low, middle, and high) and had to estimate the probability that a hypothetical patient has colon cancer. They were also given a non-medical scenario that controlled for changes in illumination and cognitive workload. Therefore, we supposed that the difference in pupil diameter between the medical and the non-medical scenario was due to emotional arousal. Results: We found that our hypothetical medical scenario had a significant effect on pupil diameter. The mean values of the mean pupil diameter in the first fifth of the fixations were higher for all risk levels in the medical scenario than in the non-medical scenario. In a more detailed analysis of the difference in pupil diameters between the two scenarios, we detected that, for the high-risk level, the emotional difference values (between the medical and non-medical scenarios) differed significantly from zero. Furthermore, we found that higher risk levels lead to higher emotional arousal and higher probability estimates. Conclusions: Even simple hypothetical medical scenarios cause emotional arousal. Thus, hypothetical medical scenarios work, and the results of studies not using real patients can be generalized to real medical situations.