Psychosomatic Medicine 32:495-502 (1970)
© 1970 American Psychosomatic Society

Influence of Triiodothyronine on Selective Attention in Man as Measured by the Visual Averaged Evoked Potential

¹ Department of Psychiatry, Stanford University Medical Center Stanford, Calif.

Address for reprint requests: B. Kopell, MD, Department of Psychiatry, Stanford University Medical Center, Stanford, Calif 94305

Man is continually bombarded by stimuli. Some contain important information while others do not. By processing some stimuli and filtering out others, man selectively attends to his environment. It is possible to obtain an objective measure of attention directed toward a specific stimulus by measuring the averaged evoked potential (AEP) produced by that stimulus. The amplitude of the AEP is greater when the subject attends to a stimulus than when he ignores it while attending to the competing stimulus. The difference between these amplitudes is a measure of selective attention. Using this measure, we compared the effects of the thyroid hormone triiodothyronine (T3) with the effects of a placebo on normal subjects. T3 increased the amplitude of the AEP when the subject ignored the stimulus but had no effect on the amplitude when the subject attended to the stimulus. T3, therefore, reduced selective attention. This reduction of selective attention may explain some of the psychopathology observed in hyperthyroidism.