A horrible factory farm environment causes pigs to recoil from a novel stimulus as if it’s a threat. By contrast, pigs raised in better circumstances explore a new stimulus expecting to find something worthwhile.
The study seems elegantly conceived, and it’s another piece of evidence highlighting the ethical problems that accompany keeping pigs in factory farms. Of course factory farmed pigs are pessimistic: they’ve never been given any reason to expect anything good to come their way. And what sort of life is that? (Thanks, Matt.) Link.