Fig. 5: Small to medium effects of hostile and neutral rebuttal compared to no response.

Internal meta-analyses of hostile rebuttal (a, b) and neutral rebuttal (c, d) versus no response on intention and attitude of the audience using random effects models. Positive effect sizes indicate that the audience’s attitude towards a behaviour dismissed by science deniers (b, d) or the intention to perform this behaviour (a, c) was higher when the advocate used hostile (a, b) or neutral (c, d) rebuttal compared to no response. The y-axes represent experiments, and the x-axes represent Cohen’s ds. Mean differences are adjusted for baseline values and standardisers are pooled standard deviations for all of the cells in the respective design⁵⁶. Diamonds show averaged effects. Red error bars indicate 95% confidence intervals. Blue error bars indicate 90% confidence intervals. The dotted central line is the zero line. If the red confidence interval does not include the zero line, then the effect is significantly different from zero. The left (−0.2) and right (0.2) dotted lines mark the equivalence bounds. If the effect lies between these lines and the blue confidence interval does not include any of the equivalence bounds, then the result is significantly equivalent, i.e., trivial. Q tests and I² indicate heterogeneity of results.