The dog on a stand within a soundproof chamber for studying conditional reflexes. Soundproofing is necessary in order to isolate the laboratory animal from accidental external stimulations. The dog is subjected to the action of only those stimuli desired by the experimentar (light, sound, food). The combined action of two or several stimuli produces a conditional reflex, a conditional connection between various sections of the brain, i.e., that act of the higher nervous activity which psychologically, studies the subjective content of consciousness, calls the process of combining or associating conceptions, i.e., the process of thought. The dogs reactions are transmitted pneumatically through a tube to the instruments located outside the chamber, then concentrated on a control desk. The experiment was performed in accordance with Pavlov's classical method of using a standard one feeding trough. The secretion of saliva in response to a stimulus (light or sound) , which in previous experiments was accompanied by the provision of food, indicate a condition reaction. This method, which at first glance seems simple, made it possible to disclose the mechanisms of higher nervous activity in is most diverse manifestation. Supplied By: SCRSS - Society for Co-operation in Russian & Soviet Studies