Privileged pigs are more optimistic
{{#rendered}} {{/rendered}}A crowd watches as a pig named 'Babe' dives into a pool of water during a peformance at Sydney's Royal Easter Show April 17, 2003. (REUTERS/David Gray)
Are you a pessimist or an optimist? If you're anything like pigs, your outlook on life may depend on your personality and mood, according to a new study.
Previous research revealed that humans' "cognitive biases" — deviations in judgment that form people's individual characteristics and personalities — are affected by mood and behavior. Now, scientists have found that the same process can affect how animals think. In a new study, scientists demonstrated for the first time that a combination of mood and personality can have a significant impact on a pig's outlook.
Pigs' personalities are either "proactive" or "reactive," according to the researchers. A proactive pig is characterized by a lively demeanor and steady behavior, whereas a reactive pig is more passive and inconsistent in its responses. In humans, proactivity and reactivity have been linked to extraversion and neuroticism; extroverted individuals tend to be more optimistic, and people with neurotic tendencies are typically more pessimistic. [7 Things That Will Make You Happy]
{{#rendered}} {{/rendered}}"Our results suggest that judgement in pigs, and potentially in other animals, is similar to [that in] humans — incorporating aspects of stable personality traits and more transient mood states," study lead author Lucy Asher, a neuroscientist at Newcastle University in England, said in a statement. "The study provides a fascinating insight into the minds of these intelligent animals and paves the way for even more in-depth studies in the future."
The researchers studied the behavior 36 domestic pigs, each classified as either proactive or reactive. Then, the researchers divided the pigs into two groups with a mix of personality types, and housed each group in a different environment known to influence their mood: One environment was more enriched, with more straw and space, and the other was plain. Next, pigs in each environment were presented with feeding bowls: One contained the positive outcome of sweets, and another contained the negative outcome of coffee beans.
Then, the researchers introduced a third, "ambiguous" feeding bowl that was empty. They observed whether the pigs approached the bowl expecting more sweets (another positive outcome), thus showing how optimistic or pessimistic each pig was.
{{#rendered}} {{/rendered}}Proactive pigs were more likely to respond optimistically. However, reactive pigs' responses depended on their environment. Those in the enriched environment, and thus in a better mood, tended to respond optimistically, the researchers said.
"The results of our study clearly show that those pigs living in a worse environment were more pessimistic, and those in a better environment were much more optimistic," said project leader Lisa Collins, a professor of animal science at the University of Lincoln in the United Kingdom. "Importantly, this finding demonstrates that humans are not unique in combining longer-term personality traits with shorter-term mood biases when making judgments."
The results of the study were published online Nov. 16 in the journal Biology Letters.
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