Cats Use Special Purr to Manipulate Humans

July 13, 2009 -- Cat owners who think their cats control them now have some scientific confirmation: Animal vocalization experts have just identified a special manipulative purr that felines have evolved, in part, to get what they want from people.

The newly identified vocalization, called "solicitation purring," has never been acknowledged or studied before, although cat fanciers, such as the study's lead author Karen McComb, are quite familiar with it.

"In the case of my cat, if he sees you stirring from sleep at all in the early morning he will immediately switch into giving this solicitation purring and position himself next to your head so you get the full impact," McComb, a reader in Behavioral Ecology at the University of Sussex, told Discovery News.

She added, "Asking around, I find I'm not the only one who, if I wake up early, often lie pretending to still be asleep so my cat doesn't start this!"

McComb, who has analyzed communication and cognition of elephants, lions and many other mammals, decided to investigate what could be behind her cat's early morning purring.

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She and colleagues Anna Taylor, Christian Wilson and Benjamin Charlton examined the acoustic structure of recorded cat purrs. The team determined purrs are not all the same, since one contains an embedded, high-pitched cry. This resulting combination makes up solicitation purring.

McComb explained that what cats seem to be doing for the special purr "is producing the low fundamental frequency and its harmonics by muscular activation" -- what has been associated with typical purring -- "but also voicing a cry, probably with the inner edges of the vocal folds, which is then superimposed on the sound's frequency spectrum."

The researchers recorded 10 cats purring. Some of the sounds contained the cry, while others didn't or were processed to have the cry component taken out. Fifty human participants then listened to the sounds, described in the latest issue of Current Biology.

Virtually all listeners, whether or not they owned a cat themselves, identified the solicitation purring sounds as being more urgent than others. Sensitivity to this type of purring may even be innate in humans, drawing from a primal drive to respond to crying babies.

"Cats have about the right size of vocal folds to produce a cry that is similar to a baby's, so there is a coincidental element," explained McComb. "In fact, the meow can sound remarkably like a crying child, which will be particularly effective with humans."