First-Signal System

a system of conditioned-reflex connections that forms in the cerebral cortex in response to the action of internal or external stimuli on human and animal receptors. The first-signal system represents reality in the form of sensations and perceptions.

The term “first-signal system” was introduced in 1932 by I. P. Pavlov during his research into the physiological mechanism of speech. According to Pavlov, in animals reality is signaled mainly by stimuli that are perceived directly by sensory receptor cells and are processed in the cerebral hemispheres. “Other than written and heard words, this is all that we internalize to form impressions, sensations, and ideas from the surrounding natural and social environments. This is the first-signal system of reality, and we have it in common with animals” (I. P. Pavlov, Poln. sobr. soch., 2nd ed., vol. 3, book 2, 1951, pp. 335–36).

In the course of a person’s working and social life, the first-signal system is supplemented by a new and specifically human system of verbal signals—the second-signal system. Pavlov wrote that “words have formed the second-signal system of reality, which is specific to us and serves as the signal for the first signals” (ibid, p. 336). Both human signal systems differ qualitatively from each other, but they interact closely and harmoniously. (See HIGHER NERVOUS ACTIVITY.)