Once a letter is selected the unselected letter will immediately be removed from the screen and the seven-second intertrial interval will begin. The schedule of reinforcement associated with this letter selection, either the FT or PT schedule, will be activated. If the PT option was selected, the time delay is activated and after the predetermined time has elapsed the monetary reward of $0.05 will be added to the individual’s reinforcement sum located at the top of the screen. Following reinforcement after the selection of the PT schedule, the PT schedule will be increased by four seconds. If the FT schedule is chosen, after 60 seconds reinforcement is added to the reinforcement sum. This key also resets the PT interval to 0 seconds. During both conditions the FT interval will be kept constant across all sessions while the PT interval will increase by four seconds after each selection. As in the Hackenberg and Joker (1994) study, each session will last 15 minutes, and a minimum of five sessions for each condition will be