Emotion Labeling in Pigeons

At an early age, humans learn words to communicate their affective states and generalize their identification across differing external conditions. One might call this collection of effects emotion labeling. Previous research investigating analogous effects in nonverbal animal models has largely used drug-induced affective states or metacognitive states that are difficult to control. Some progress has been made by conceptualizing affect as a point within a two-dimensional space with pleasure on one axis and arousal on the other. Distinct affective states may thus serve as cues that control both human and non-human behavior. If conditions supporting responding produce distinct affect, labeling in one circumstance may transfer to novel conditions that elicit the same affective state. The present experiment examined the labeling of affective states induced in pigeons via outcomes of either the delivery of food or its omission. These outcomes followed responses (pecks) made in the presence of three visual stimuli (A, B, and C). On A trials, each outcome was followed by two labels; pecks to one of two labels, depending on whether food was delivered or omitted, were required to progress to the next trial. All pigeons labeled accurately. Consistent with human emotion labeling, pigeons learned to select a label associated with different core affect-inducing outcomes, transferred appropriately to novel conditions (i.e., trials with B and C in Test 1 and 2), and probably relied on more than just external cues (Test 3).