Suppression (constriction). Scales 5 (Mf) and 0 (Si) are sometimes referred to as suppressor scales because, if either or both are elevated, they tend to suppress or "soften" the expression of characteristics suggested by other elevated scores. Acting Out (impul sivity). In contrast to Scales 5 (Mf) and 0 (SO, Scales 4 (Pd), and 9 (Ma) are sometimes referred to as "releaser" or "exci tator y scales"; and if one or both are elevated, the person is likely to act out difficulties. This hypothesis is further strengthened if 0 (Si) is also quite low.