The paper presents the study of constructing a researcher’s digital identity in virtual scientific environment. In online communication, the set of true researcher identity characteristics (sex, age, status and nationality) appears to be incomplete and is represented through his/her communicative strategies. The digital identity of a social network ResearchGate user, which is represented in their discourse of virtual scientific discussions, is studied using an integral model of identity including cognitive, emotional, motivational, behavioral and other components. The present study focuses on the discursive representation of the cognitive dimension of a digital identity. The communicative behavior of a researcher is analyzed regarding the following semantic and pragmatic features expressed in the analyzed discourse by a range of specific linguistic devices: 1) explicitness of cognitive processes represented by the frequent use of cognitive verbs as well as the words and expressions denoting cognitive processes related to knowledge and understanding; 2) types of cognitive evaluation and judgement in informal communication represented mainly by the modifiers indicating a specific type of evaluation (probability, value, complexity, novelty and correspondence with scientific norms); 3) self-identification and identification of an interlocutor as a member of ‘our’ or ‘their’ research field as well as explicit representation of symmetric and asymmetric relations between the interlocutors in terms of experience in the field.