The article aims to study the dynamics of psychological and psychophysiological indicators of students’ cognitive activity in a digital learning environment. As a research platform, we used the well-known task of speed–accuracy tradeoff, adapted for work in the LMS Moodle using a set of plug-ins that implement both the stimulus situation itself and the ability to monitor the characteristics of the user’s motor activity displayed in the track of the cursor control device (mouse tracking). As part of the study, LMS users performed a cognitive test, included in the digital learning environment and demonstrating the manifestation of Fits’s law in two versions: with instructions for the accuracy and speed of searching for the center of a reference figure that appears on a computer screen. The results were obtained in the form of tracks of the movement of a computer mouse, the main characteristics of the motor activity of the subjects – the time to complete both parts of the test, the distance traveled, the accuracy of hitting targets, and speed and acceleration – were analyzed and evaluated. All participants’ indicators significantly differed depending on the stages of the experiment. These studies were presented in the form of a set of formal statistical generalizations and visualization, reflecting the characteristic features of the subjects’ actions, the distance traveled, speed and acceleration on all segments of the path. As a result of data analysis, 6 groups of users were identified, differing in the degree of severity of indicators in terms of the characteristics of speed, accuracy and amplitude of movement. Of particular interest were such traces of a person’s actions, which, on the one hand, were an expression of his skills or experiences, and, on the other hand, were available not only for subjective, but also for objective analysis. As an example, we can point to the handwriting of a person who became one of the promising objects of study by psychologists of the early twentieth century. The concept of “handwriting” was easily transferred to other ways of transmitting information, for example, to the work of an operator with a key when transmitting messages using the “Morse code” method. Thus, the use of a computer mouse monitoring system in a digital learning environment provides an opportunity to quickly and adaptively provide interaction with the user, taking into account their psychophysiological characteristics and emotional state. The proposed diagnostic system allows us not only to determine the quantitative characteristics of the path traveled and the click map of a computer mouse, but also to classify the user into one or another group, taking into account their psychological characteristics.