It turns out that pigs make arbitrary decisions for the same reasons humans do. They get moody and moody, and they let those feelings dictate judgment. By subjecting pigs to a series of experiments involving chocolate sweets and uncomfortable beds, a group of British researchers found that pigs have some of the same psychological blind spots as humans.
Scientists have long known that humans suffer from cognitive biases that stem from our fundamental personalities interacting with more transient moods. University of Newcastle neuroscientist Lucy Asher and colleagues explain in a Biology Letters paper that pig personalities can be classified into two groups: proactive and reactive. Proactive pigs tend to be outgoing, inflexible and optimistic, while reactive pigs are neurotic and easily influenced by their environment. The researchers ran personality tests on 36 pigs to determine whether they were proactive or reactive and then placed them in different situations where they had to decide in a split second whether to hunt for a hidden treat.
Here’s how it worked. For several days in a row, the pigs were given a double-bottomed dish containing three delicious chocolate sweets. The bowl would always be put in the exact same spot. At the same time, the pigs were given a similar dish with the (among pigs) so hated coffee beans under the false bottom. The disgusting coffee dish was also prominently displayed. After a while, the pigs learned to rush for the dish in the chocolate spot and ignore the dish in the coffee spot. (Both dishes were coated in sugar, so they smelled the same.) These learning sessions also gave the researchers an idea of how quickly the pigs would move to the dish if they were optimistic about finding a hidden tasty treat.
Then they completely turned the pig world upside down. They started putting dishes in new places between the chocolate and coffee spots to introduce uncertainty. To find out if mood and personality would affect what pigs did, they changed one more thing. They put a number of pigs in large pens with toys and fluffy straw beds. Others put them in smaller cages without a straw. The pigs without straw were significantly less satisfied with their housing and were put in quite a bad mood.
Next came the real test of the pig’s personality and temper. Would the environment affect the proactive and reactive pigs differently, showing a mix of mood and personality in decision making? Indeed it did. The generally optimistic view of proactive pigs was largely unaffected by their less comfortable room. They approached most of the dishes as if they were treat dishes, moving quickly to open the false bottoms. That said, they haven’t forgotten their old lessons. The closer the dish was to the coffee spot, the less likely they were to act quickly. The reactive pigs, on the other hand, were so bothered by their uncomfortable beds that they didn’t even bother to approach dishes that weren’t covered in the chocolate stain. They reacted decidedly pessimistic, deciding that any dish other than the chocolate stain was probably a terrible coffee dish. Why bother checking?
What’s fascinating here is that we’re seeing quite complex emotional behavior. The proactive pigs and reactive pigs didn’t just trade on personality traits. Their decisions depended on the circumstances. Uncomfortable pens caused bad moods – and those moods interacted with their personalities to dictate behavior. Put a group of pigs in terrible conditions, where all they get is hard beds and coffee, and they won’t all react in the same way. Some will sink into pessimism, while others will continue, hoping to find chocolates hidden in new places.
Biology Letters2016. DOI: 10.1098/rsbl.2016.0402