Symptom misinformation: Participants were provided with feedback for some symptoms (targets), misleadingly suggesting that a slight majority of their peers experienced these targets on a regular basis; symptom ratings went down for control but not for target symptoms

Merckelbach, H., Dalsklev, M., van Helvoort, D., Boskovic, I., & Otgaar, H. (2018). Symptom self-reports are susceptible to misinformation. Psychology of Consciousness: Theory, Research, and Practice, http://dx.doi.org/10.1037/cns0000159

Abstract: We examined whether self-reported symptoms are affected by explicit and implicit misinformation. In Experiment 1, undergraduates (N = 60) rated how often they experienced somatic and psychological symptoms. During a subsequent interview, they were exposed to misinformation about 2 of their ratings: One was inflated (upgraded misinformation), whereas another was deflated (downgraded misinformation). Close to 82% of the participants accepted the upward symptom misinformation, whereas 67% accepted the downward manipulation. Also, 27% confabulated reasons for upgraded symptom ratings, whereas 8% confabulated reasons for downgraded ratings. At a follow-up test, some days later, participants (n = 55) tended to escalate their symptom ratings in accordance with the upgraded misinformation. Such internalization was less clear for downgraded misinformation. There was no statistically significant relation between dissociativity and acceptance or internalization of symptom misinformation. In Experiment 2, a more subtle and implicit form of misinformation was employed. Undergraduates (N = 50) completed a checklist of symptoms and were provided with feedback for some symptoms (targets), misleadingly suggesting that a slight majority of their peers experienced these targets on a regular basis. Next, participants rated the checklist again. Overall, symptom ratings went down for control but not for target symptoms. Taken together, our results demonstrate that symptom reports are susceptible to misinformation. The systematic study of symptom misinformation may help to understand iatrogenic effects in psychotherapy.