The article is devoted to a general problem of digital technologies’ influence on cognitive processes, viz. long-term changes in selective attention of adult Internet users. The study is based on two postulates of a psychologist, Lev Vygotsky: the idea of an indirect structure of cultural functions and a genetic law that determines its decay as a comeback to a simpler organizational level. The study was carried out through a comparative analysis of the voluntary attention of adults who prefer different code systems: traditional printed or modern digital. Conventionally, we divided the participants into 2 groups: the readers (n=50, aged 46.18±6,71, 21 males and 29 females) and the Internet users (n=50, aged 45.38±5,86, 21 males and 29 females). The parameters were estimated via “The arrangement of the numbers” test. As starting points, we took the average results established in the pre-digital era, on one hand; and the indicators of attention of young, active Internet users (to clarify the results of the study, an additional group was comprised), on the other hand. The revealed empirical facts showed that the voluntary attention is significantly better in the group of the readers (p≤0.01). Their indicators are close to the norm of the “pre-digital” people. The indicators of the Internet users are closer to the one of young Internet users, both in accuracy (p≤0.05) and distribution (р>0.05). We suggest positing a significant deterioration of selective attention as a cognitive deformation phenomenon, which is expressed in the regression of higher mental functions to its more primitive levels