Knowledge structuring is one of the poorly-studied cognitive processes that significantly affect the learning activity processes as well as professional knowledge sharing communications. The paper describes the main results of the study aimed at investigation of the impact of the individual characteristics of cognitive style in the process of information structuring during learning. The stress is put on the study of the cognitive style parameters, which significantly affect the conceptual design features of hierarchical models (the so-called ontologies) that are important for learning and understanding of the material. The main described results are focused on empirical testing of hypotheses about the impact of the individual characteristics of cognitive style (such as field dependence/field independence, category narrowness/width, impulsiveness/ reflexivity) on the individual and collective ontology design features. Some interesting results of the group ontology design work study (in pairs and threesomes) are discussed. They present the relationship between the individual ideas of group members about the domain and the resulting common structure. The sample consists of the Saint-Petersburg Polytechnic University students. The students were tested on the specifics of their individual cognitive styles and after they were asked to create ontologies of the "Computer Science" domain personally and collectively. The obtained results allow to propose some practical recommendations for formation of the efficient groups for collective intellectual work, e.g. data base design, knowledge representation models, business-models and other conceptual structures.