Experimental Psychology and Psychopathology in Animals1
In the psychical experiments the animal is excited by the properties of the external object, which are unessential for the activity of the salivary glands, or even entirely accidental. The salivary glands are stimulated not only by the properties of the objects unessential for the work of the glands, but absolutely by all the conditions surrounding these objects, or with which they are connected one way or another—for example, the dish in which they are contained, the article on which they are placed, the room, the people who usually bring the objects, even the noises produced by these people, though the latter may not be seen at the given moment—their voices, even the sound of their steps. Thus, in psychical experiments, the connection of the objects acting as stimuli on the salivary glands becomes more and more distant and delicate. The significance of the distant signs of objects producing a motor reaction in the organism, is, of course, easily recognised.