The second signal system as conceived by Pavlov and his disciples.

Pavlov clearly formulated his ideas on the second signal system (specifically, language) in the 1930s. This occurred in conjunction with his interest in interspecies differences and in the study of human neuroses. Pavlov proposed that conditional reflexes signal concrete reality while symbolic-language provides abstractions of reality. Phylogenetically, language emerged in the humans because this form of communication had survival value to the species. Pavlov's disciples L. A. Orbeli and N. I. Krasnogorskiĭ had considered the ontogenetic development of language. The experimental investigation of A. G. Ivanov-Smolenskiĭ extended Pavlov's empirical study of the function of language in psychopathology. Notwithstanding a sustained interest in language, Pavlov did not develop a theory of language acquisition based upon the conditioning principle. Pavlov's conceptualization of language may not have been original, nor did it contribute significantly to modern linguistics. It is now mainly of historical interest. It was, nevertheless, important to the conceptualization of neuroses within the context of the theory of higher nervous activity and it had far-reaching political implications for Soviet psychology in the immediate post-World War II period.