Fig. 4.

Forest plot illustrating the standardized mean differences (SMD), individual effect sizes, overall effect size and heterogeneity statistics for the meta-analysis examining changes in alpha power from a control (non-stressed) condition to a stress condition. Hofmann et al., 2005 and Hofmann (2006) report a baseline - anticipatory phase comparison; Al-Shargie 2017a, 2017b, Hafeez et al., 2018 and Ehrhardt et al., 2021 report a control condition - reactive phase comparison; Betti et al., 2018 and Guo et al., 2019 report a baseline - recovery phase comparison.