Pigs can feel optimistic or pessimistic, depending on how they are treated, a study says. 一项研究表明，猪会依据对待他们的好坏，表现出乐观或者悲观的情绪。 Animals kept in ‘luxury’ are more likely to respond positively to a new experience than those in less stimulating pens. 在安逸环境下的动物比那些在糟糕环境中的动物对新事物表现得更加乐观。
Scientists hope the research, which shows pigs are capable of complex emotions, will have an impact on animal welfare. 科学家们希望这个展示了猪有复杂感情的研究可以对动物身心健康研究做出贡献。 The Newcastle University team, led by Dr Catherine Douglas, devised a technique to ‘ask’ pigs if they were feeling good or bad about life as a result of the way in which they lived. 来自Newcastle大学研究组的凯瑟琳道格拉斯博士指导了这次试验，并发明了一项可以“询问”猪对所居住坏境是否满意的技术。
Half of the pigs were then placed in an enriched environment –more space, straw and toys – while the others were put in a smaller, boring pen. 一半猪被放在良好的的环境下，有更多空间，稻草和玩具。而另一半猪则被放在狭小又吵闹的空间。
The team then played an ambiguous noise – a squeak – and studied how the pigs responded. 研究组把这些猪被放在一种嘈杂环境中，并研究这些猪会作何反应。 Dr Douglas said: ‘The pigs in the enriched environment were optimistic about new noise and approached. " 道格拉斯博士说：“在良好环境下的猪更加愿意接受新的噪音，”
‘The pigs in the boring environment were pessimistic and, fearing it might be the bag, did not approach for a treat. “而在不好环境中的猪则更加悲观，以为这种声音可能是要来猎捕他们的声音，并不会把这当做一种乐趣。”