Visual Effects on Finger Tremor in Normal Subjects and Anxious Patients

¹ Lecturer, Institute of Psychiatry, Maudsley Hospital, Denmark Hill, London, S.E.5.

The physiological tremor occurring at the metacarpophalangeal joint of the index was observed during extension of this finger against a load of 50G. The tremor characteristics (1) during visual monitoring of a display of positional error, and (2) following eye closure, were studied in 22 anxious patients and a matched group of normal subjects.

Harmonic analysis showed that the average tremor amplitude at each of 12 frequencies between 2 and 14 c/s was relatively larger in the patient group under both recording conditions.

The pooled data from the control subjects showed a relatively smaller tremor amplitude at each frequency when the eyes were closed, with particularly marked attenuation at 8-10 c/s.

Fourteen of the patients showed a relatively increased tremor amplitude after eye closure at 6 or more of the 12 frequencies studied when compared with the amplitudes observed when they were monitoring the visual display of performance. This pattern was seen in only 3 subjects in the control series. This type of response to eye closure was significantly more common in the series of patients than in the control group.