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Cats Use Special Purr to Manipulate Humans

Jennifer Viegas, Discovery News

Hear Me Purr! | Discovery News Video

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.

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."

Cats purr to each other, but the scientists found felines really exaggerate
their solicitation purring when communicating with humans, making
felines near impossible to ignore.

Georgia Mason, a professor and Canada Research Chair in Animal Welfare
at the University of Guelph, told Discovery News she was pleased to see
that "this careful work shows there are at least two types of purring: the
shrill ones cats wake you up with, and the relaxing one they do at other
times."

"It makes me wonder whether dogs and cats learn to make sounds we
find particularly hard to ignore, or whether we have selected for animals
whose signals we find naturally recognizable and comprehensible,"
Mason added.

Both she and McComb hope future studies will continue to unravel the
mysteries of cat vocalizations, since they believe purring alone may be
much more complex than previously thought, with various types of purrs,
such as those emitted when cats are in pain, conveying different information.

Posted on SHARE Yahoo group - July 14, 2009