The Tower of Silence

in the Institute of Experimental Medicine

Ivan Pavlov page

Studying the conditional reflexes Pavlov came to the necessity to isolate completely the experimental dog from any exterior influences during the experiment.
For this purpose he made a project of a very special construction, named "Tower of Silence", with  8 experimental sound-proof cameras, separated by spiral staircases and passages with noiseless covering. With the help of Prince Oldenburgsky and Ledenzov charitable company this project was realized in 1913-1917.

The walls and window glasses were very thick. Within the camera  another camera was suspended, with a double door. During the experiment the dog was placed into the inside camera, which was additionally vibration-isolated. 

To register the saliva the channel of the parotid gland was leaded out to form a salivary fistula. A metal capsule (funnel) was fixed on the cheek. The funnel was connected with the water-air system and the glass tube on the scale with the help of the rubber tube. When saliva appeared, it pressed the air in the rubber tube, affecting the water in the glass tube with the scale, which showed the quantity of secreted saliva.

Usually the experiment took 30-40 min during which the experimental dog was closed in the camera. All the stimuli were passed mechanically, the observation was performed through periscope.

At present such a severe isolation is not used. Even in Pavlov's time it was noticed, that some dogs became troubled, started to whine, scratch, some went to sleep and didn't react to conditional stimuli. During the great flood in Leningrad in 1924 Pavlov obtained new materials, when some of the animals suffered from water. Pavlov started a new direction in his investigations: study of experimental neuroses and the types of the high nervous activity ( in parallel to human temperament).

Department of Physiology