236 PSYCHOTHERAPY : SCIENTIFIC AND RELIGIOUS chap.
were the same, except that in one case a positive response was being conditioned, and in the other a negative or inhibitory response. ^
The negative conditioned reflex is a very important part of Pavlov's general theory. Pavlov and his coworkers in Moscow have extended their experiments to other animals, and also to young children.
In the case of a young child it is arranged that the child shall lie on its back on a couch in a room separated from the experimenter's room, with a bulb fixed under his chin, working a manometer, so that whenever it opens its mouth this movement is registered. An arrangement is rigged up whereby chocolates can drop into the child's mouth. That is the stimulus the pleasant stimulus. Pavlov found the child would respond by opening its mouth when neutral stimuli were presented if they had been associated previously with the subsequent presentation of food. And what is very important is that, compared with the dog, the child developed a conditioned reflex much more quickly. Whereas the dog will require, say, 120 experiments to get the conditioned reflex thoroughly established, in the case of a child it may be established after 20 or 25 repetitions, and can also be abolished more quickly.
Until his death in 1935 Pavlov carried out similar experiments, leaving behind him a flourishing school.
A further interesting example of the conditioned reflex is furnished by HudginsI02 on the contraction of the pupil of the eye. He flashed a light upon the subject's eye, at the same time saying the word ' contract ' ; and then, after a moment, extinguished the light. This process he repeated one hundred times, and after this found that the eye contracted at his command without the use of the light. Later it became possible for the