Reinforcement, “the more informative stimulus will be the more effective secondary reinforcer” (p.97). An “informative stimulus” was assumed to be one which predicted accurately that a response would be followed by a reinforcing stimulus, and which did not have its information value assimilated by some other stimulus. This latter characteristic is difficult to predict: It depends not just on degree of redundancy, but on attentional and perceptual factors. However, for purposes of the experiment, Egger and Miller assumed that a stimulus which always occurred within the temporal bounds of another stimulus (see Figure 15.22) should acquire little or on secondary reinforcing strength because its information value would be assimilated