The machine-like accuracy of many of the frog’s actions gives a basis for the belief that the animal is merely an automaton. Certain it is that one is safe in calling almost all the frog’s actions reflex or instinctive. During months of study of the reaction-time of the frog I was constantly impressed with the uniformity of action and surprised at the absence of evidences of profiting by experience. In order to supplement the casual observations on the associations of the green frog made in the course of reaction-time experiments, the tests described in this paper were made. They do not give a complete view of the associative processes, but rather such a glimpse as will enable us to form some conception of the relation of the mental life of the frog to that of other animals. This paper presents the outlines of work the details of which I hope to give later.
II. EXPERIMENTAL STUDY OF HABITS.
A. The Chief Problems for which solutions were sought in the following experimental study were: (1) Those of associability in general, its characteristics, and the rapidity of learning; (2) of discrimination, including the parts played in associative processes by the different senses, and the delicacy of discrimination in each; (3) of the modifiability of associational reactions and general adaptation in the frog, and (4) of the permanency of associations.
B. Simple Associations, as studied in connection with reaction-time work, show that the green frog profits by experience very slowly as compared with most vertebrates. The animals have individual peculiarities in reaction which enable one in a short time to recognize any individual. To these characteristic peculiarities they stick tenaciously. One, for instance, always jumps upward when strongly stimulated; another has a certain corner of the tank in which it prefers to sit. Their habits are remarkably strong and invariable, and new ones are slowly formed. While using a large reaction box I noticed that the frogs, after having once escaped from an opening which could be made by pushing aside a curtain at a certain point in the box, tended to return to that place as soon as they were again put into the box. This appeared to be evidence of an association; but the fact that