Happy Pigs
Experts from the university’s School of Agriculture, Food and Rural Development have shown for the first time that a pig’s mood mirrors how content he is, highlighting that pigs are capable of complex emotions which are directly influenced by the environment in which they live.
Led by Dr Catherine Douglas, the team has employed a technique to ‘ask’ pigs if they are feeling optimistic or pessimistic about life as a result of the way in which they live.
In an experiment reminiscent of Pavlov’s dogs, the Newcastle team taught the pigs to associate a note on a glockenspiel with a treat – an apple – and a dog training ‘clicker’ with something unpleasant – in this case rustling a plastic bag.
The next step was to place half the pigs in an enriched environment – more space, freedom to roam in straw and play with ‘pig’ toys – while the other half were placed in a smaller, boring environment– no straw and only one non-interactive toy.
The team then played an ambiguous noise – a squeak – and studied how the pigs responded. Dr Douglas said the results were compelling.
“We found that almost without exception, the pigs in the enriched environment were optimistic about what this new noise could mean and approached expecting to get the treat,” she said. “In contrast, the pigs in the boring environment were pessimistic about this new strange noise and, fearing it might be the mildly unpleasant plastic bag, did not approach for a treat.
“It’s a response we see all the time in humans where how we are feeling affects our judgement of ambiguous events. For example, if you’re having a bad day -feeling stressed and low - and you’re presented with an ambiguous cue such as your boss calling you into their office, the first thing that goes through your head is what have I done wrong? We call this a negative cognitive bias. But on a good day you greet the same ambiguous event far more positively, you might strut in expecting a slap on the back and a pay rise.
“This ‘glass half empty versus glass half full’ interpretation of life reflects our complex emotional states, and our study shows that we can get the same information from pigs. We can use this technique to finally answer important questions about animal welfare in relation to a range of farm environments, for pigs and potentially other farm animals.”
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