This article examines the methodology of empirical research in psychology that was developed in Russia to study the structure and content of consciousness at different levels, individual or group, with varying degrees of accessibility for reflection. The psychosemantic method stems from studies implementing Charles Osgood’s semantic differential and George Kelly’s personal construct theory. The construction of a semantic space is different from measurement procedures in the natural sciences. Rather, a system of categorical structures and connotative meanings serves as a reference for empathy, immersion of oneself in an individual or collective mentality of the other (or, in the case of studying self-understanding and reflection, in one’s own). From this perspective, psychosemantic methods are related to projective psychological tests but are more formalized, objective, and verifiable. This paper provides an account of the quantitative operational indicators applied in psychosemantics to conduct comparative studies. These indicators include the dimensionality of semantic space, (i.e., a number of generalized categories that form this space, and their hierarchical and organizational structure), and the comparative measures of similarity between spaces. Examples of using the psychosemantic approach in studying the process of categorization and perception in altered states of consciousness under hypnosis, in developmental psychology, political psychology, and psychology of art, are presented. The article presents the research carried out by the authors over different years and does not set itself the task of describing the entirety of Russian psychology on the problem of consciousness and the unconscious.