Retardation of mentation in depressives: Posner's covert orientation of visual attention test.

A double-key version of Posner's covert orientation of visual attention test, which involves shifting of preparation for response from one side to another, was administered to 32 depressives and 32 controls to evidence retardation of mentation in depressives and compare it to symptom-rating scales. Results showed depressives' overall response times to be consistently slower than controls. The time of maximal response preparation occurred later in depressives than in controls, showing clear evidence of pure retardation of mentation (not mixed with motor processes). This slowing of mentation was strongly correlated with observable psychomotor retardation but not with depressive severity.