| Abstract: | A discrete-trial procedure was used to measure 4 White Carneaux pigeons' choices between FR and VR schedules and between fixed and variable delays before reinforcement. A peck at a green key produced a reinforcement schedule that was constant within a condition but varied across conditions. A peck at a red key produced a ratio schedule (or, in other conditions, a simple delay) whose size was increased or decreased many times a session, depending on the S's previous choices. The purpose of these adjustments was to estimate an indifference point—a ratio size (or delay duration) at which the S chose each key about equally often. The results were used to test the present author's (see record 1985-19333-001) equivalence rule for choices between fixed and variable schedules. This rule predicted the major trends in the obtained indifference points from both ratio and delay conditions, but better predictions were generated with a more complex equation that included parameters reflecting the Ss' sensitivities to delay of reinforcement and to events of different probabilities. It is concluded that a successful equivalence rule must include parameters that can be adjusted to describe the effects of delay and probability in a given experimental setting. Once these parameters are estimated, however, choices involving both fixed and variable delays and FRs and VRs can be accurately predicted with the same equation. (20 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved) |
