Fig. 3.

Interaction plot of effect sizes by event-related potential (ERP) effect and contrast. (a) Mid-frontal ERP effect. (b) Parietal effect. Filled circles show effect sizes (Hedge’s g) for each study, shaded areas show the probability density function of the data, and boxplots show the median and interquartile range. Insets illustrate the electrode inclusion criteria for each effect (note that mid-frontal effects had to have been measured symmetrically, whereas electrode groupings for parietal effects could have been left-sided or symmetrical; see Methods – Inclusion criteria)