  Fleck defines a thought style as the readiness for directed perception, with corresponding mental and objective assimilation of what has been so perceived, characterized by specific problems of interest, by judgments which the thought collective considers evident and by methods which are applied as a means of cognition (1935a, IV.3). What was collectively developed plays an active role in cognition: shapes modes of perception and the thinking of members of a thought collective. An individual, who has assimilated a certain thought style, becomes  passive when conducting standard research: recognizes in environment specific forms and draws specific—those and no other—conclusions from an assimilated theory and results of experimental research.