Irrational behavior in dogs (Canis lupus familiaris): A violation of independence from irrelevant alternatives

We tested dogs for a violation of independence from irrelevant alternatives, which would indicate irrational behavior. In Experiment 1, we offered 10 dogs' choices among alternative passages. The target passage led to more food than the competitor passage but required dogs to enter a narrower passage. The decoy passage asymmetrically dominated the competitor passage because although it contained a larger amount of food, it was narrower than the target passage. We found that dogs increased their preference for the target passage in the presence of the decoy passage, which violated the assumption of independence from irrelevant alternatives. Our second experiment controlled for energetic hunger state because previous findings had suggested that the violation effect might arise from changes in energetic state (Schuck-Paim et al., 2004). We provided supplementary feedings to each dog between each trial such that each dog consumed the same amount of food on each trial. The violation of independence from irrelevant alternatives effect persisted, though to a lesser degree than in Experiment 1. Cognitive implications are discussed.