The relative importance of reinforced versus nonreinforced stimuli in visual discrimination learning by redwinged blackbirds (Agelaius phoeniceus)

Abstract

Redwinged blackbirds were trained to locate and peck apple slices in two discrimination problems with four times more training on one problem than on the other. The birds were then given transfer tests with the stimuli re-paired. Nonreinforced (S-) stimuli exerted greater control over behavior than did reinforced (S+) stimuli. We inferred that the blackbirds learned more about what to avoid than what to approach when searching for food in the two-choice situation. That inference is contrary to the notion that, by being alert to the visual cues which signal foods (i.e., S+ stimuli), birds can more successfully cope with irrelevant visual information encountered during foraging. Rather, being alert to cues which signal the absence of food (i.e., S- stimuli) may be relatively more important.