Reexamining psychokinesis: comment on Bösch, Steinkamp, and Boller (2006)

H. Bösch, F. Steinkamp, and E. Boller's review of the evidence for psychokinesis confirms many of the authors' earlier findings. The authors agree with Bösch et al. that existing studies provide statistical evidence for psychokinesis, that the evidence is generally of high methodological quality, and that effect sizes are distributed heterogeneously. Bösch et al. postulated the heterogeneity is attributable to selective reporting and thus that psychokinesis is "not proven." However, Bösch et al. assumed that effect size is entirely independent of sample size. For these experiments, this assumption is incorrect; it also guarantees heterogeneity. The authors maintain that selective reporting is an implausible explanation for the observed data and hence that these studies provide evidence for a genuine psychokinetic effect.