Repeated exposure to others' pain reduces vicarious pain intensity estimation

Pain perception in others can be influenced by different contextual factors. In clinical settings, the repeated exposure to others' pain has been proposed as a factor that could explain underestimation of patients' pain by health care providers. Previous research supported this idea by showing that repeated exposure to persons in pain biases the subsequent willingness to impute pain in others. However, it remains unclear if the effect of repeated exposure on the detection of pain extends to deliberate pain estimation of stimuli presented for a longer period.

Therefore, in a first experiment, healthy participants were either exposed to clips of facial expressions of intense pain or neutral expressions before estimating the intensity of other individuals' pain expressions. To test the specificity of this effect with regard to the pain content, a second study was conducted with healthy adults, which compared the effect of exposure to fear, pain and neutral videos on subsequent pain assessment in others.

Results from the first experiment indicated that repeated exposure to others' pain diminished the subsequent estimation of the intensity of pain in others. Results from the second experiment suggested that exposure to fear could bias pain estimation in a similar manner. However, the absence of difference in ratings between the exposure to fear and neutral groups warrants caution in the interpretation of these findings.

By demonstrating that repeated exposure to others' pain diminished subsequent pain estimation in others, this study adds relevant information on the factors that could contribute to pain underestimation in health care professionals. WHAT DOES THIS STUDY ADD?: Repeated exposure to facial expressions of intense pain not only biases pain detection, but also pain estimation in others. Prior exposure to facial expressions of pain compared to exposure to neutral ones leads to a reduced estimation of others' pain. This effect is not specific to pain as exposure to another negative emotion (fear) also biases subsequent pain estimation. These results support the interpretation that the underestimation of patients' pain by health care professionals could be related to repeated exposure to other's pain.