Discussion

To summarize the study results, we accumulated data from 77 studies that examined the relationship between the Tellegen Absorption Scale and a measure of hypnotic susceptibility. We found no differences in effect size among conference presentations, published or unpublished studies. More recent studies had lower effect sizes than older ones. The type of hypnotizability scale had a significant effect on the absorption and hypnotizability relationship; with the CURSS and HGSA having the lowest mean correlations followed by the SHSSC, HIP and Other Categories. Depending on the hypnosis scale used, correlations between susceptibility ranged from .25 to .41.

One criticism of meta-analysis is that the results of a meta-analytic study are affected by publication bias. This refers to the hypothesized tendency for studies with significant results to be published, or accepted for conference presentations, while editors and reviewers generally reject studies with statistically non-significant results. Accordingly unpublished research would be expected to have lower mean effect sizes than either those studies that have been published or were conference presentations. We found no evidence of a publication bias in the present literature sample. There were no statistically significant differences in the mean effect sizes among published or unpublished studies, or those studies presented at conferences or symposia.