Reinforcement of variations and repetitions along three independent response dimensions

Reinforcement was presented contingent upon human subjects simultaneously varying three dimensions of an operant response. The response was drawing rectangles on a computer screen. The dimensions were area of the rectangle, its location on the screen, and its shape. In Experiment 1, an experimental group was reinforced for satisfying the three-part variability contingency. A control group was equally reinforced for drawing rectangles but independently of levels of variability. Results showed that the experimental group varied significantly more along each of the dimensions than did the control group. In Experiment 2, another group of subjects was reinforced for repeating instances along one of the dimensions, e.g. repeatedly draw a rectangle in approximately the same location, while simultaneously varying along the other two dimensions. The subjects learned to satisfy these contingencies as well. These results show reinforcement simultaneously and independently controls the variability of three orthogonal dimensions of a response.