The memory scanning performance of both unipolar and bipolar depressives and patients with anxiety states was compared with that of control subjects. Four versions of Sternberg's memory comparison task were used. Unipolar depressives showed impaired memory scanning in 3 of the tasks compared with controls, and in one task compared with patients with anxiety states. They were also slower than the other patients and controls in the non-scanning processing stages. They seemed to adopt a less efficient search strategy, and showed more controlled processing as opposed to automatic detection in a paper-and-pencil version of the task.