Cats mix baby 'cry' with purr to score dinner

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Hungry house cats have a way of changing their purr to manipulate humans into making a dash for the can opener, a new study shows.

Karen McComb and her team of researchers from the University of Sussex say some cats mix a high-pitched cry within their purr specifically to push their owner's buttons when angling for a meal. They claim cats appear to be burying the "cry" within an otherwise pleasant purr to exploit innate tendencies humans have for nurturing offspring.

This vocal blend, which McComb calls a "solicitation purr", is hard for humans to ignore but is also less likely to get the cat ejected from the bedroom than meowing.

The researchers say a crucial factor of the noise is a high-frequency element embedded within the naturally low-pitched sound of a cat's purr.

"The embedding of a cry within a call that we normally associate with contentment is quite a subtle means of eliciting a response — and solicitation purring is probably more acceptable to humans than overt meowing."

McComb and her colleagues said they played recordings of regular and solicitation purrs to volunteers. They found even those with no experience of cats found the solicitation purrs to be "more urgent and less pleasant" than regular purring. When the team re-synthesized these purrs to remove the embedded cry, the urgency ratings for the purrs decreased significantly.

Not all cats, however, are in on the ruse: "It seems to most often develop in cats that have a one-on-one with their owners rather than in large household where there is a lot going on and such purring might get overlooked," she said. "Meowing seems to be more common in these situations."

House cats the team studied also apparently had a tendency not to perform when strangers were on the premises. "Cats exhibit this behavior in private with their owners, typically at anti-social times, such as first thing in the morning," McComb said.

"I've worked on communication and cognitive abilities in a wide range of mammals, including elephants and lions, but domestic cats were one of the most challenging subjects to date," she added.

The team's findings, The cry embedded within the purr, appear in the July 14 issue of the journal Current Biology.

Audio examples of solicitation and non-soliciation purrs are available here. ®