750 



SCIENCE. 



[N. S. Vol. VII. No. 178. 



the highly gifted. The question of flatness of 

 the world had, with the masses, hardly an ex- 

 istence ; no molecules of the brain were exer- 

 cised by it ; the disturbance occurred only 

 among the learned. Is it for this reason that 

 we find so few survivals, to-day, of those who 

 believe the world is flat ? 



Edwakd S. Moese. 

 Salem, May 17, '98. 



'the new psychology.' 

 To THE Editor of Science : Professor Stan- 

 ley's interesting letter is timely and valuable ; 

 it calls attention to a fundamental difference in 

 standpoint between two schools of psychologists. 

 This difference has been indicated by Professor 

 Cattell in the following statement : " As a sci- 

 ence advances beyond the stage of crude obser- 

 vation it tends to become either quantitative 

 or genetic." The former tendency has pro- 

 duced experimental psychology ; the latter 

 genetic psychology. 



The standpoint of experimental psychology — 

 as far as I can understand the principles of its 

 representatives — can be briefly stated as fol- 

 lows : Oiven a group of phenomena, called ^ phe- 

 nomena of consciousness ;'' required a determina- 

 tion of the laws according to which these phenom- 

 ena are connected. This is a problem similar 

 to that of astronomy, physics, meteorology, 

 geology, biology, political economy — in fact, 

 of all the sciences. In the early stages of 

 a science the only solutions possible are 

 those of 'yes' and 'no;' e. g., does the 

 memory of an object improve with interest 

 and the lapse of time ? to which the answers 

 are : ' yes ' for the former and ' no ' for the 

 latter. The introduction of methods of meas- 

 urement — which is the special achievement of 

 the new psychology— renders quite a different 

 solution possible. The question just stated be- 

 comes : how does the memory of an object de- 

 pend on interest and the lapse of time? The 

 answer is as follows : Denote all the possible 

 factors that may influence the memory by a, h, 

 C) • • • , i, • • ■ , t, ■ ■ ■ , X. Keeping all the cir- 

 cumstances except i constant, determine the rela- 

 tion of dependence of the memory on i, which 

 is simply a roundabout method of saying : Let 

 a, b, e, . . . = const, and find_Jlif=f(i), where 



Mis the accuracy or uncertainty or some other 

 property of memory in the particular case. The 

 method of solution, familiar to all experimental- 

 ists (see p. 77 of ' New Psychology '), consists in 

 varying i quantitatively and measuring the re- 

 sulting variations in M; the results when prop- 

 erly treated give a formula connecting the two ; 

 this is known as a law of memory. The fun- 

 damental necessity for such work is the method 

 of measuring the quantities considered. 



Professor Stanley remarks : ' ' We must first 

 devise some method of measuring interest ;" it 

 follows that we cannot determine this law of 

 memory because such a method has not been 

 found. This is quite true ; the proper reply is 

 to devise such a method — an undertaking not 

 difficult to any one trained in psychological 

 experiments. We can, however, measure time, 

 and have in a number of cases (Wolfe, Ebbing- 

 haus) determined the laws of various kinds of 

 memory as depending on time or M={(t). The 

 ideal solution — which Professor Stanley seems 

 to expect at the start — is M=F (a, b, c, . . . , i, 

 . . . , t, . . . , x) or the determination of the 

 complete law of memory as depending on 

 every possible circumstance. Perhaps some 

 day psychology will make some approximation 

 to such a solution ; at present it must remain 

 content with determining single laws. 



Professor Stanley is quite wrong in assuming 

 that this method is peculiarly a physical method. 

 It belongs no more to physics than to chemistry 

 (see the late works on mathematical chemistry), 

 to political economy (Carnot, Jevons, Fisher), 

 to biology (Pearson). It is merely a fundamen- 

 tal method of thought which is applicable wher- 

 ever measurements can be made. In fact, we 

 can reply to Professor Stanley that his science 

 of genetic psychology must inevitably come to 

 the use of this very method. Every single fac- 

 tor influencing the life of an individual or a 

 community acts to a degree depending on its 

 intensity according to some law ; supposing all 

 other factors to remain constant, this law is 

 given by its action under those circumstances. 

 By carefully measuring the action of each factor 

 and its result on each property of mental life, 

 the genetic psychologist could state the result 

 as a series of laws of mental development. To 

 be sure, this is rather a difficult task to propose, 



