for National Geographic News
Rats are clever little creatures.
Sure, they can run mazes for scientific experiments and learn to procure food by pressing levers and deciphering complex clues.
But rats may be even smarter and more like humans than was previously suspected, a new study says.
Traditional animal psychology says that animals "reason" by association.
For example, in 1903 Russian physiologist Ivan Pavlov famously trained dogs to salivate at the sound of a metronome. He did so by starting the noise just before feeding time, day after day. Soon, the dogs were associating the sound with the upcoming treat and would salivate even if no food were offered.
Psychologists call this learning by association.
But that doesn't explain everything, says Aaron Blaisdell, a behavioral neuroscientist at the University of California, Los Angeles.
There is also "causal reasoning"as in, cause and effectand it's a very different thing from associative learning.
In their study, to be published in tomorrow's issue of the journal Science, Blaisdell and his colleagues determined that rats can understand complex cause-and-effect relationships.
Cause and Coincidence
The researchers designed a multistep experiment involving lights, noises, levers, and food.
In the first step the rats were periodically exposed to ten-second flashes of light. Sometimes the light was followed by a tone. Sometimes it was followed by the release of a sweet liquid.
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