Reading from the screen of an electronic device (ED) is a significant cognitive activity for adolescences, and its complexity affects visceral functions. We conducted an analysis of the heart rate variability (HRV) and eye movements (EM) in adolescents while they were reading complex text on an ED screen. The aim was to assess the functional state characteristics under these conditions and reveal the intensity (“cost”) associated with this activity The study involved 22 adolescences with an average age of 15 years (М = 15.46, SD = 0.44). Reading text from an ED screen in adolescents was associated with a high functional “cost,” characterized by a decrease in overall HRV, an increase in the tension index and heart rate. These changes indicate the functional tension of regulatory systems during cognitive activity. The study revealed varying levels of parafoveal processing involvement. For the majority of adolescents (86.4%), word-by-word reading and a low percentage of regressions (12.0%) were observed, suggesting developed average reading skill. However, a qualitative analysis of individual EM tracks indicated varying level of reading skill development among adolescents, possibly due to a limited vocabulary and a lack of understanding of syntax. Additionally, 40.9% of adolescents demonstrated poor text comprehension. Our results showed that reading remains a complex cognitive task for adolescents, despite the expectation that their reading skills should be well-developed and automated by this age. Individual analysis of HRV and EM in adolescents with varying levels of text comprehension during reading demonstrated different strategies of adaptive behavior and autonomic reactions when performing a complex cognitive task. The functional “cost” of information processing when reading text from the ED screen results from a combination of age-related and individual adaptation characteristics, language competence and the psycholinguistic complexity of the text.
