Introduction. This paper discusses possibilities for using an integrated (psychophysiological and experimental psychological) approach to diagnosing cognitive processes to objectify disorders in patients with schizophrenia. This study represents the first attempt to apply psychophysiological methods to diagnose impairments in perception and thinking in schizophrenia. It is important to clarify the relationship between cognitive functioning and functional states of magnocellular and parvocellular neural visual networks and their dynamics during the development and progression of schizophrenia. The authors’ intention is to provide convincing evidence that the imbalance between these neural systems leads to impairments in the integrity of visual perception and, subsequently, to impairments in selective thinking, which makes it difficult to assess and recognize meaningful, essential information when forming judgments, and impedes the construction of a full and adequate world picture. Methods. The study used the methods of visocontrastometry; contrast sensitivity and immunity to interference were assessed. To diagnose cognitive functions, the study used an experimental psychological method combined with the following neuro-and pathopsychological diagnostic tools: Exclusion of the 4th Superfluous, Comparison of Concepts, Poppelreuter Test, and Incomplete Images. Results and Discussion. The authors examined functional states of the magnocellular and parvocellular visual systems, characteristics of their interaction, and cognitive functions at different stages of the disease. Psychophysiological characteristics of perception are associated with the processes of perception, memory, attention, and thinking. The findings indicate that magnocellular system is associated with the characteristics of perception, working memory, and characteristics of attention. Hyperactivation of the magnocellular system is accompanied by impairments in selective attention. Magno-and parvocellular systems (mechanisms of global and local analysis) contribute to the realization of thinking processes. Hypoactivation of the parvocellular system leads to a decrease in selective thinking. Progression of schizophrenia is accompanied by a decrease in the activity of both neural systems.