CHAPTER VI.
HOW WE EXPERIMENT ON THE MIND--EXPERIMENTAL PSYCHOLOGY.
In recent years the growth of the method of experimenting with bodies in laboratories in the different sciences has served to raise the question whether the mind may not be experimented with also.

This question has been solved in so far that psychologists produce artificial changes in the stimulations to the senses and in the arrangements of the objects and conditions existing about a person, and so secure changes also in his mental states.

What we have seen of Physiological Psychology illustrates this general way of proceeding, for in such studies, changes in the physiological processes, as in breathing, etc., are considered as causing changes in the mind.

In Experimental Psychology, however, as distinguished from Physiological Psychology, we agree to take only those influences which are outside the body, such as light, sound, temperature, etc., keeping the subject as normal as possible in all respects.
A great many laboratories have now been established in connection with the universities in Germany, France, and the United States.

They differ very much from one another, but their common purpose is so to experiment upon the mind, through changes in the stimulations to which the individual is subjected, that tests may be made of his sensations, his ability to remember, the exactness and kind of movements, etc.
The working of these laboratories and the sort of research carried out in them may be illustrated best, perhaps, by a description of some of the results, apparatus, methods, etc., employed in my own laboratory during the past year.