ALTERATIONS IN THE MEMORY CODE FOR TEMPORAL EVENTS INDUCED BY DIFFERENTIAL OUTCOME EXPECTANCIES IN PIGEONS

The effect of differential outcome expectancies on memory for temporal and nontemporal information was examined. Pigeons were trained to mat ch short (2-sec) and long (8-sec) sample durations to red and green co mparison stimuli, and vertical and horizontal lines to vertical and ho rizontal comparison stimuli. In Experiment 1, one differential outcome (DO) group received food for correct choices on short-sample trials, whereas another received food for correct choices on long-sample trial s. On line-orientation trials, half of each DO group received food for correct responses following vertical samples, whereas the other half received food for correct responses following horizontal samples. Over all retention was greater in the DO groups than in a nondifferential ( DO) group that received either food or no food for correct responses o n a random half of all trials. Furthermore, although the NDO group dis played a choose-short bias for temporal samples, both DO groups displa yed equivalent biases to select the comparison stimulus associated wit h food. In Experiment 2, differential outcome expectancies were exting uished off-baseline. Subsequently, in the first nondifferential outcom e test session, the DO groups performed less accurately than the NDO g roup. These findings indicate that temporal samples are not retrospect ively and analogically coded when they are differentially associated w ith food and no food. Instead, they are remembered in terms of the cor responding outcome expectancies.