On the mechanisms of the formation of backward connections.

In a study carried out on dogs by Pavlov's methods of classical and instrumental alimentary conditioning the influence of the duration of intervals between paired stimuli has been shown on the manifestation of backward connections: the shorter the interval the more distinct their manifestation. The percentage of Backward connections was much higher after multiple reinforcements than after a single one. The effects of interval duration as well as of repeated presentation of paired stimuli on backward connections show that these factors are of considerable importance for their formation.