2o6 CARNEGIE INSTITUTION 



cholog}' proper is meant the investigation of the mind b)' experi- 

 menting upon normal individuals through the ordinary avenues of 

 sense, or, in other words, through stimulations to the nervous sys- 

 tem. It includes the experimental investigation of sensation in all 

 its kinds, namely, vision, hearing, touch, muscular sensation, etc. 

 In this department considerable advance has been made in recent 

 years. Delicate problems, for example, of the theory of vision, 

 including questions of space perception, of color vision, of visual 

 association with other sensations, are now profitably taken up, and 

 standard apparatus for the investigation and demonstration of such 

 phenomena has in some cases been devised. The practical utility 

 of an equipment for experimental psj^chology, in connection with 

 the Carnegie Institution, would appear in the prosecution of such 

 subjects as that of the investigation of color perception and its 

 defects in connection with colored lights, railway signals, etc., the 

 training of the senses, etc., where at present the greatest confusion 

 and disorder prevails. Citing these as instances, merely, in but one 

 of the departments of sensation, where many of equal importance 

 might be cited, one is able to see theutilitj' of a well equipped labo- 

 ratory for such research, where, if necessary, the work on any single 

 problem in any department may be pursued. 



In physiological psychology, on the other hand, the main prob- 

 lem is to investigate mental conditions in connection with the 

 physiological processes which accompany them, and more particu- 

 larly in the variations which are presented b}- accident, disease, etc., 

 or which are direct!}^ arranged by the experimenter. Here the 

 science of what may be called neuro-psychologj^ or psycho-physiology 

 has been developed. To cite in this connection also a single line of 

 research, we ma}' refer to the localization of functions in the brain 

 and the remarkable advances in the physiology and pathology of 

 speech. This work has constituted one of the most interesting 

 pages in the history of modern physiology and medicine, no less 

 than a contribution of extreme importance to our understanding of 

 the relations of mind and body. Areas have been located in the 

 brain, as, for, example, that of the function of speech, so definitely 

 and presenting such marked mental symptoms that the surgeon is 

 able by a direct operation to reach the spot, and cure the patient. 

 Our point of emphasis here is that the symptoms are mental, that 

 there are variations or derangements of sensation or movement, as 

 in the case of speech, and the experimental knowledge acquired and 

 the mode of treatment really belong to psj^chology. The equip- 



