Abstract
Pigeons were trained in a two-key, concurrent-chains choice procedure to investigate the effects of increased relative duration of reinforcement on preference. Throughout the study, the initial- and terminal-link schedules were equal for both choices. Across conditions, the duration of reinforcement in the terminal links was either equal or unequal. Equal durations were 3 s versus 3 s. Unequal durations were 3 s versus 6 s. Pigeons accessed the relatively longer duration of reinforcement via a food hopper elevated for one 6-s reinforcement interval or two successive 3-s reinforcement intervals separated by a 0.1-s blackout. The color of the light that illuminated the relatively longer duration was either the same as or different from the color of the light that illuminated the relatively shorter duration. A significantly greater mean preference ratio was recorded in conditions in which the hopper lights were different and when the 6-s reinforcement interval was presented as two successive 3-s hopper activations. The combination of the two procedures resulted in the greatest significant increase in preference. The differential hopper lights and multiple successive intervals of grain access facilitated the discrimination of the longer duration of reinforcement and allowed the hopper to replenish with grain, respectively. The combined arrangement of increased access to grain resulted in enhanced control of preference by the relative reinforcement duration.