That might seem like an overly-fine distinction, but the authors point out that the three mental states are different. Depressed animals would lose interest in pleasurable activities, while apathetic animals would lose interest in all activities. Bored animals, on the other hand, should perk up at the sign of any new activity because they seek stimulation.
The team decided to test 29 captive black mink at a research farm at Michigan State University. Sixteen mink lived in spartan cages with little to entertain them, while the other 13 lived in “enriched” cages with tunnels to wading troughs and frequently-replenished supplies of toys.
The researchers observed the animals for a week, then presented them with various types of stimulation. Some stimuli, such as air puffs and the silhouette of a predator, were intended to be negative. A moving toothbrush, which mink like to chase, was supposed to be positive. And other stimuli, such as maracas and the smell of peppermint, weren’t obviously good or bad.
The mink in the plain cages were more interested in the stimuli than mink in enriched cages, regardless of whether the stimulus was positive or negative. The deprived animals approached the stimulus sooner and spent more time investigating it. They also scarfed down more treats such as Fancy Feast cat food and hot dog pieces, suggesting they hadn’t lost interest in pleasurable activities. The results “are broadly consistent with boredom,” the authors write in PLoS ONE.
Mink that were more interested in the stimuli tended to lie awake with their eyes open, the researchers found. But they didn’t perform more repetitive motions such as scratching the cage wall. Rather than being a symptom of boredom, repetitive movement “may actually help to alleviate that boredom,” the team writes. — Roberta Kwok | 16 November 2012
Source: Meagher, R.K. and G.J. Mason. 2012. Environmental enrichment reduces signs of boredom in caged mink. PLoS ONE doi: 10.1371/journal.pone.0049180.
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