Do conditional reinforcers count?

Abstract

Six pigeons were trained on a procedure in which seven components arranged different food-delivery ratios on concurrent variable-interval schedules each session. The components were unsignaled, lasted for 10 food deliveries, and occurred in random order with a 60-s blackout between components. The schedules were arranged using a switching-key procedure in which two responses on a center key changed the schedules and associated stimuli on two side keys. In Experiment 1, over five conditions, an increasing proportion of food deliveries accompanied by a magazine light was replaced with the presentation of the magazine light only. Local analyses of preference showed preference pulses toward the alternative that had just produced either a food-plus-magazine-light or magazine-light-only presentation, but pulses after food deliveries were always greater than those after magazine lights. Increasing proportions of magazine lights did not change the size of preference pulses after food or magazine-light presentations. Experiment 2 investigated the effects of correlations between food ratios and magazine-light ratios: In Condition 6, magazine-light ratios in components were inversely correlated (-1.0) with food ratios, and in Condition 7, magazine-light ratios were uncorrelated with food ratios. In Conditions 8 and 9, pecks also produced occasional 2.5-s flashes of a green keylight. In Condition 8, food and magazine-light ratios were correlated 1.0 whereas food and green-key ratios were correlated -1.0. In Condition 9, food and green-key ratios were correlated 1.0 whereas food and magazine-light ratios were correlated -1.0. Preference pulses toward alternatives after magazine lights and green keys depended on the correlation between these event ratios and the food ratios: If the ratios were correlated +1.0, positive preference pulses resulted; if the correlation was -1.0, preference pulses were negative. These results suggest that the Law of Effect has more to do with events signaling consequences than with strengthening responses.