The determiners of behavior at a choice point.

T h e question I am going to discuss is the very straightforward and specific one of “why rats turn the way they do, at a given choice-point in a given maze at a given stage of learning.” The first item in the answer is fairly obvious. They turn the way they do because they have on the preceding trials met this same choicepoint together with such and such further objects or situations, down the one path and down the other, for such and such a number of preceding trials. Let me, however, analyze this further, with the aid of a couple of diagrams. First, consider a diagram of a single choice point (Figure 1). In this figure the point of choice itself is designated as 0,; the complex of stimulus-objects met going down the left alley, as O,, that met going down the right alley, as OR; the goal at the left, as 0,; and that at the right, as OcR. The behavior of turning to the left is represented by the arrow B,; and that of turning to the right, by the arrow BE. And Presidential address delivered before the American Psychological Association, Minneapolis,