This is an ACT-R model of the Myers, Fort, Katz, and Suydam (1963) choice experiment. In the experiment subjects were to press one of two buttons on each trial, and were informed after choosing whether it was the correct button. The correct button to press was randomly chosen on each trial, with a probability p for button 1 and 1-p for button 2. One group of subjects was paid 10 cents for each correct answer, another group was paid 1 cent, and another group was not paid.
Each subject was given 300 practice trials under a fixed probability p (of 0.6, 0.7, or 0.8) and then tested on another 100 trials. Choice proportion on these final 100 trials was used as the outcome measure for each subject.