Experiment 1 shows that prior discrimination learning and steady-state testing procedures
sharpen the gradient; Experiment 2 shows that within-subjects testing of the range of generalization
stimuli also sharpens the gradient. In addition, Experiment 2 shows that, in case
of very flat initial generalization, an orderly gradient can reveal itself through differential
rates of extinction learning. Finally, Experiment 2 also evidenced an orderly gradient
of generalization-of-extinction. These results suggest that discrimination processes have
an important effect on the generalization of predictive learning in humans, and highlight
behavioral analogies between animal conditioning and human predictive learning.