is it half full or half empty? cognitive bias and animal welfare

A glass sits on the table in front of you, filled up to its halfway point. Is it half empty, or half full? How you answer is actually related to your current emotional state, and similar patterns have been observed in species in our care at Brookfield Zoo Chicago as well.

Both humans and animals experience cognitive biases, which are systematic errors in thought processes that occur when we take in and interpret information in our environment. One common cognitive bias is confirmation bias, or the tendency to seek out or favor information that supports our current beliefs or values. The bias relating to our aforementioned glass of water is judgement bias, or the tendency of individuals to assume that ambiguous cues (like a glass filled halfway) lead to negative outcomes (“That’s half empty…”) rather than positive outcomes (“That’s half full!”).

Why do these biases exist, especially if they often lead us to the wrong answer or an inaccurate conclusion? We have to make hundreds of individual decisions on a daily basis, so these biases can act as “mental shortcuts,” called heuristics, to help us quickly act and not become overwhelmed by all of the information around us. For example, when meeting someone new, we may mentally compare them to someone who acts similarly in order to quickly decide whether they are trustworthy, rather than taking the time to learn more about this specific individual. As we have learned more about the animal kingdom, it is clear that animals regularly experience cognitive biases during their decisions, ranging from where they will forage to the social partner with whom they will interact.

But cognitive biases are also strongly linked to emotional states. Studies have shown that humans and animals that are in a positive emotional, or affective, state are more likely to judge ambiguous cues optimistically, or think the glass is half full, so to speak. Those in a negative emotional state, on the other hand, are more likely to think pessimistically, or think the glass is half empty. Due to this established association between cognitive biases and emotional state, scientists have developed cognitive bias tests to give to animals to provide insights on their otherwise inscrutable internal emotional state. Soon we will be examining the cognitive biases and emotional states of the dolphins at Brookfield Zoo Chicago.

In dolphins, tests of cognitive bias are predicated on a measure called “return latency.” Prior to testing, dolphins are trained to swim to trainers on points on opposite sides of a pool, and then return to their initial trainer to receive a reward. However, the reward for swimming to one side of the pool is always larger than the other, so we would expect that the dolphin’s speed when swimming back to the initial trainer to receive its reward (its return latency) would be faster when anticipating the larger reward than the smaller reward. Next, trainers are positioned on points in between the two opposite points (the ambiguous cue, or the glass filled halfway). Now, based on whether the dolphin swims more quickly (anticipating a larger reward, or the half full glass) or more slowly (anticipating a smaller reward, or the half empty glass), we can observe whether the dolphin is in a positive or negative emotional state.

Previous work has reported that more pessimistic dolphins display more anticipatory behavior, and more optimistic dolphins display more social behaviors. In our study, we will conduct similar tests to investigate whether there are any relationships between what vocalizations a dolphin produces and their emotional state. Check back in for future updates to learn about our results, and see what our dolphins’ vocalizations may be telling us about their emotions!

Dr. Charles Ritzler
Animal Welfare Scientist
Published October 14, 2024