To the Editor.—
Evaluation of normal controls in various psychobiological tests is essential to describe abnormalities in different psychiatric illnesses. Generally, a "normal" control sample is collected from project staff or through a newspaper advertisement. However, in these normal volunteers, systematic clinical evaluation is rarely carried out other than in a short unstructured or semistructured interview. Recently, we carried out systematic evaluations of research volunteers to collect and characterize a normal control pool. To our surprise, a history of serious psychiatric illnesses was found in more than half of the putatively normal paid research volunteers. This stresses the need for such a systematic approach in collecting a sample of normal controls for psychobiological testings.
Methods and Results.—
An advertisement was placed in major metropolitan and suburban area newspapers recruiting normal research volunteers "to participate in interviews, measurements of eye movements, and sleep studies." The research center where all the procedures