Online consent risk-warnings about negative psychological side-effects do not change participant expectations or cause negative psychological side-effects

Risk-warnings delivered as part of informed consent in psychological trauma-related research potentially cause negative outcomes for participants (e.g. Abu-Rus et al., 2019; Bridgland & Takarangi, 2021). For instance, risk-warnings might suggest psychological side-effects (e.g. distress) to participants, causing them to expect to experience, and subsequently manifest, these side-effects (i.e. nocebo effects; Benedetti et al., 2007). But, in a psychological trauma-related context, there is scant research addressing this possibility. Therefore, we randomly allocated online participants (N = 200) to encounter a risk-warning (e.g. "you may experience distress") or no warning during informed consent procedures, prior to an online trauma analogue paradigm. Opposing our predictions-and signalling good news for Institutional Review Boards and researchers-we found no evidence that warned participants reported more negative expectancies or experienced psychological nocebo effects (e.g. distress). Because risk-warnings are used as a harm mitigation strategy, and we did not find that people's expectancies differed, our findings raise concerns over how effective risk-warnings are in guiding people's decision-making during the consent process. Thus, our research has implications for informing and warning participants in trauma-related research.