Z-scores representing SWM response relative to vigilance for each of the 19 clusters were screened for outliers using 3 regression-based diagnostic approaches: Studentized deleted residuals > ±3, leverage values >0.17, and Mahalanobis distance > critical value > 16.27 (p = 0.001, dfbetas > ±1 or dffits > ±1). One case was determined as unduly influential in the right cerebellar tonsil.
