488 THE POPULAR SCIENCE MONTHLY. 



THE TIME IT TAKES TO THINK. 



Br J. McK. CATTELL. 



ALL science is partly descriptive and partly theoretical. Care 

 must, however, be taken lest too much theory be built up with- 

 out sufficient foundation of fact, or there is danger of ei-ecting pseudo- 

 sciences, such as astrology and alchemy. The theories of the con- 

 servation of energy and of the evolution of species are more interesting 

 to us than the separate facts of physics and biology, but facts should 

 be gathered before theories are made. The way of truth is a long 

 way, and short cuts are apt to waste more time than they save. 

 Psychology is the last of the sciences, and its present business seems 

 to bo the investigation of the facts of consciousness by means of 

 observation and experiment. Everywhere in science experiment is 

 w^orth more than observation ; it is said that the evidence in pathology 

 is so contradictory that almost anything can be proved by clinical 

 cases. Psychology, owing to its very nature, must always depend 

 largely on observation for its facts, and some progress has been made 

 in spite of the difficulties lying in the way of introspection and the 

 correct interpretation of the actions of others. The application of 

 experimental methods to the study of mind is, however, an impoilant 

 step in advance, and would seem to be a conclusive answer to those 

 who, with Kant, hold that psychology can never become an exact 

 science. I propose explaining here how we can measure the time it 

 takes to think, and hope this example may show that the first fruits 

 of experimental psychology are not altogether insignificant or unin- 

 teresting. Just as the astronomer measures the distance to the stars 

 and the chemist finds atomic weights, so the psychologist can deter- 

 mine the time taken up by our mental processes. It seems to me the 

 psychical facts are not less important than the physical ; for it must 

 be borne in mind that the faster we think, the more we live in the 

 same number of years.* 



It is not possible directly to measure the time taken up by mental 

 processes, for we can not record the moment either of their beginning 

 or of their end. We must determine the interval between the pro- 

 duction of some external change which excites mental processes, and 

 a movement made after these processes have taken place. Thus, if 

 people join hands in a circle, and one of them, A, presses the hand of 

 his neighbor B, and he as soon as possible afterward the hand of C, 

 and so on round and round, the second pressure will be felt by each of 

 the persons at an interval after the first, the time depending on the 

 number of people in the circle. After the hand of one of the persons 



*Thc results I am about to give are based on experiments, detailed accounts of which 

 I have printed in recent volumes of " Mind," " Brain," and " rhilosophische Studien." 



