In the era of digital transformation of society and education, the mental development of a child goes differently than before. The purpose of the article is to briefly analyse the state of study of the problem of the influence of digital media on the cognitive development of pre-school and primary school age students. The analysis of foreign and domestic studies revealed the insufficiency, fragmentation and inconsistency of available data on the peculiarities of the cognitive sphere of students using digital media. Noting the impossibility of cancelling the sociocultural evolution of the psyche in the new digital environment, the prospect of systemic research into the child's mental development in the conditions of mixed reality on the basis of the working concept of digital socialisation is emphasised. The analysis of studies of the possible positive and negative effects of school education under conditions of digitalisation has shown the increasing cognitive inefficiency of this largely spontaneous practice. Since the digit itself is not capable of transforming information into knowledge and action, the transition to a properly organised digital education system requires the substantiation of the theory of effective digital learning and the development of digital educational products that offer new ways of organising students' attention, memory, thinking and communication, adequate to their age and psychological characteristics.