The effect of inter-sensory stimulation on dark adaptation and night vision.

Abstract

Three expts. were performed to test recent Russian claims that intersensory stimulation and light muscular exercise significantly improve dark adaptation. In the 1st expt., 6 subjects were tested with a Hecht-Shlaer adaptometer on 11 consecutive days. Exptl. treatments consisted of smelling oil of wintergreen, listening to a 1000-cycle tone, and performing light muscular exercise on a bicycle ergometer. Control and exptl. dark-adaptation sessions were varied systematically from day to day. In the 2d expt., 5 subjects were tested on 5 consecutive days with the Luckiesh-Moss Low-Contrast Test-Chart. The stimuli used here were a loud and soft tone and a heavy and light pressure applied to the back of the hand. The 3d expt. measured the effects of similar stimuli on form discrimination at very low illumination levels. The results of all expts. were completely negative. None of the stimuli used either facilitated or inhibited dark adaptation, contrast sensitivity, or form discrimination at low illuminations.