ANALYSIS OF INDIVIDUAL VARIABILITY IN COM PLEX TASK ACQUISITION AS A METHOD TO DIFFERENTIATE STAGES OF LEARNING

Two-way active avoidance learning is a complex task characterized by a high level of interindividual variability. We have demonstrated in ou r previous paper that rats with different rate of learning vary in exp ression of freezing responses, which reflects a conflict tendency not to reenter the previous chock compartment [4]. In the present work we analyzed as main indices the proportions of avoidance, rapid escape, a nd freezing responses and their distribution within a session. Sequenc es of occurrence of these three types of responses were examined in gr oups of rats with different success of avoidance learning. The obtaine d results confirmed a hypothesis that overcoming the conflict tendency was a separate stage of learning which preceded avoidance response ap pearance and subsequent stabilization. Only in rats which failed to le arn and develop avoidance responses within the first session, freezing responses were observed in successive session being indicative of rea ppearance of the conflict tendency. The intensity of the conflict tend ency did not depend on the type of the first response of an animal (fl eeing or freezing) to an unexpected aversive stimulus.