Assessing Judgment Bias in Ambassador Animals: Two Case Studies

Judgment bias tasks assess optimism and pessimism through responses to ambiguous stimuli. When interacting with ambiguous stimuli, optimistic individuals anticipate receiving a reward whereas pessimistic individuals anticipate a lack of reward, with these differing expectations reflected in approach time. Researchers have used these tests to assess animals’ reactions to assumed positive and negative contexts, but rarely to assess the effects of participation in ambassador programs. We tested two ambassador animals—a domestic chicken (Gallus domesticus) and a red tegu (Salvator rufescens)—after exposure to zoo visitors. Once they learned that a container on the left contained food whereas a container on the right contained no food, we introduced an ambiguous container equidistant from the left and right locations. We assessed the chicken’s judgment biases when she was perched or held. We assessed the tegu’s judgment bias when visitors were allowed to touch him or not. The chicken displayed pessimism whether she was held or perched, but the tegu displayed pessimism only when no visitor touch occurred, suggesting that touch may not be aversive to the tegu, but that interacting with visitors may have deleterious effects on the chicken. We encourage the use of these tests to inform the use of animals in ambassador programs.