Rat lovers appreciate the creatures' sweet natures and intelligence. Others have issues with the naked tails and plague associations. But most rat aficionados are aware of the idea that rats enjoy being tickled and will "laugh" when stimulated. Turns out that's not a blanket statement for all rats.
Researchers at the University of Bristol in the UK took a closer look at the laughing-rat phenomenon to determine if the rodents actually like to be tickled. So they tickled some rats and monitored their high-pitched vocalizations.
"The researchers found not all rats like to be tickled and that some rats emitted very high numbers of calls whilst others did not, and these calls are directly related with their emotional experience," the University of Bristol said in a statement on Monday. Rats that laughed the most also had the highest positive emotional response to tickling. Those that didn't laugh weren't enjoying it.
Rat giggling has been the subject of studies before. Check out this Scientific American video showing how researchers listen in on ultrasonic rodent laughter.
The new study, published this week in the journal Current Biology, could help improve animal welfare, not just for pet rats, but also for those kept in laboratories.
"What we have shown in this study," said lead researcher Emma Robinson, a psychopharmacologist at Bristol, "is that the vocalizations made by rats in response to tickling are an accurate reflection of their emotional experience and something which is easy to measure."