The syntactic complexity effect size co-varies with overall sensitivity to language. The mean size, across participants, of the syntactic complexity effect (object-extracted > subject-extracted) is plotted against the mean effect size of the overall response to language, as estimated in the localizer experiment (sentences > fixation). To control for inter-individual differences in the overall response strength, data for the eight fROIs were z-scored within each participant prior to averaging. Crosses show standard errors across participants for both effects. A dashed, black line depicts the linear regression line for predicting the syntactic complexity effect based on the overall language response, and was estimated for visualization purposes only (the linear mixed-effects regression reported in the Results section was carried out using individual data from all participants).