Theoretical-experimental analysis of the psychosemantic approach to the study of motivational structures of personality is presented. Ascription of motives by student subjects to different deeds taken from students' life has been studied. Categorical structure of the individual mind determining perception and evaluation of deeds has been modelled in the form of subjective semantic spaces. General principles of reconstruction of semantic spaces which structurally organize motives and deeds are considered and realized on the basis of data obtained on a particular subject. Role of psychosemantic methods is discussed against other methods used for the study of the personality.