DEVELOPMENT OF MODERN COMPARATIVE PSYCHOLOGY 



501 



from the domination of human psychology 

 and the definite commitment of the science 

 to an objective, natural science viewpoint. 



Experimental developments 



In spite of such promising beginnings, 

 the experimental movement did not get 

 well under way until about the opening of 

 the present century. Aside from the 

 experiments of Morgan on birds, only a 

 few scattered studies had been made on the 

 higher vertebrates. The decade centering 

 around 1900 is especially important 

 as marking the beginnings of labora- 

 tory work on the mammals. A more 

 widespread application of experimental 

 methods to lower forms also took place, 

 as we shall see. The work began more or 

 less independently along many lines and 

 the leadership includes physiologists and 

 zoologists as well as psychologists. The 

 developments were so varied and exten- 

 sive, and so much originality was shown 

 in the application and elaboration of 

 methods that had come down from the 

 earlier pioneers, that this decade appears 

 to be no less epochal than the former one 

 had been. 



Before tracing through the more impor- 

 tant lines of progress developing out of 

 this period, it may not be amiss to state 

 the fundamental ground of distinction 

 between mere observation and genuine 

 experiment. As in all the natural sciences 

 the distinguishing mark of experimental 

 procedure in the strict sense is the con- 

 sistent use of artificial controls resulting in 

 precise, quantitative results. From Aris- 

 totle downward, naturalists have intro- 

 duced more or less simple controls of one 

 sort or another into field or indoor obser- 

 vation of behavior when an occasional 

 problem seemed to suggest it. Usually, 

 however, such controls have involved no 

 more than the arrangement of a selected 

 stimulus situation within the natural 



environment of the organism, without 

 seeking to control, in any adequate way, 

 the free movements of the animal under 

 test. The ingenious devices of Fabre are 

 good examples of crude attempts to 

 control the stimulus situation in the open. 

 The study by Galton of auditory range in 

 birds is an interesting application of this 

 semi-experimental method to higher forms . 

 Galton had the quaint habit of concealing 

 his newly invented whistle in his hands, 

 and producing various pitches from time 

 to time, while walking about in the 

 zoological parks of London, in the mean- 

 time making a tabulation of the different 

 species of bird that appeared to take note 

 of sounds of various pitch. 



In the strict sense, however, experi- 

 mental behavior methods require control 

 of both the stimulus situation and the 

 organism under test by some appropriate 

 technique of the laboratory type. Obvi- 

 ously no sharp line can be drawn between 

 careful field observation and simple experi- 

 mental procedure. In a very proper sense, 

 the laboratory may be considered as a 

 limited and controllable field in which 

 isolation and quantitative measurement of 

 selected aspects of behavior can be made. 

 As a rule experimentalists have shown a 

 sympathetic interest in adapting experi- 

 mental situations and general living 

 conditions in the laboratory to the natural 

 proclivities of the animal tested, insofar as 

 these have been adequately understood. 

 Our emphasis upon experimental develop- 

 ments in this historical connection does 

 not mean that systematic observation is to 

 be rated as of slight value in behavior 

 work. Field observation must always 

 hold a place of honor in the biological 

 sciences and particularly so in comparative 

 psychology. Many important problems 

 depend for their final solution upon 

 competent field work, either wholly or in 

 part. Nevertheless, it cannot be denied 



