[Effect of genotype and environment on individual features of the orientation reaction in man].

Autonomic responses and evoked potentials were recorded in situation of orienting reaction in 86 twins. On the basis of experimental and literature data a hypothesis is suggested on the existence of two subsystems of orienting reaction--a block of informational regulation and a block of motivational regulation characterized by different functions and, probably, by different neurophysiological mechanisms. The activity of the first block is formed mainly by environmental factors while the activity of the second one--mainly by the genotype.