Psychophysical Analysis of the Skin Sensitivity to Light Exposure: a Pilot Study

Background. The study of the mechanisms of sensation, primarily visual, emergence under the influence of a light stimulus on a person is a classic task for psychological science. At the same time, little attention has been paid to the sensations arising from light exposure of the skin surface, despite the surprising results obtained in a well-known series of experiments by Russian psychologist A.N. Leontiev. The task of studying skin-optical sensitivity with the modern element base of experimental equipment is relevant from the point of view of the development of the general psychological theory of activity and understanding sensory-perceptual processes of sensation formation due to light exposure.
Objective of the study was to investigate the ability of subjects to recognize the effect of light on their skin surface. Methods. A specially designed experimental setup was used for the purpose of the study, which included a LED light source and a control programme. The experimental procedure involved the psychophysical method of two-alternative forced choice. The main experiment consisted of three series of cycles for each participant: first, 10 cycles were presented to fix the initial state; 100 cycles followed to train the subject; then, 10 cycles were used to fix the final state.
Sample. 12 participants took part in the experiment.
Results. showed that the number of correct answers when determining the cycle phase corresponding to the LED switching on, is significantly more than 50% (t = 10,992, df = 1414, p < 0.001).
Conclusion. The conclusions of A.N. Leontiev and N.B. Poznanskaya about the possibility of skin sensitivity to light exposure were confirmed. A biophysical hypothesis is proposed to explain the result.

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