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Science Friday > Archives > 2000 > January > January 7, 2000:

Hour One: Monkey Math / Moon Matters

If you've been feeling down about your math skills, this isn't going to help matters any. Two groups of researchers have published results this week that indicate monkeys may have some math abilities similar to that of preschoolers.

One group, at Columbia University in New York, first taught several rhesus monkeys to count from one to four. They gave the monkeys a tasty treat when they touched pictures of groups of objects in the correct order (one blue triangle, then two red trucks, then three green trees...). After the monkeys had the order of 1-4 down, the researchers then showed the monkeys pictures that they had never seen before of groups of 5-9 objects. The monkeys successfully ordered the new pictures by number as well, showing that they hadn't just memorized one, two, three - they understood conceptually that five objects was more than seven objects.

A second group, based in Japan, found that a chimp could remember a random sequence of 5 numbers, much as a preschool child can. Adult humans can generally recall sequences of up to 7 numbers -- the means we use to recall telephone numbers, for example. What do these experiments say about the fundamentals of math -- and of psychology? You'll have a chance to call in and talk to the researchers during this hour.

We'll also take a look at the moon. If you've ever felt that the moon looks larger when it's near the horizon than when it's high in the sky, listen up: a father-son team of researchers has been trying to find out why. The moon is actually pretty constant in its distance to the Earth - and the moon's size in the sky is pretty constant, too. It's all an illusion, but scientists have often debated just how that illusion works. The question boils down to whether the brain uses the apparent size of an object to judge its distance, or vice versa.

Using computer simulations, researchers Lloyd and James Kaufman have reached the conclusion that the illusion is created by the brain basing its size estimates on apparent distance, and not the other way around. When the moon is at the horizon, they say, the brain has extra information telling it "the horizon is far away -- that moon must be large to be so visible." When the moon is high in the sky, away from the horizon, those clues aren't there, so the brain assumes the moon to be closer and not as large. How'd the researchers figure this out? Tune in and see - and try some of the experiments yourself on the computer! We'll also take your calls about an upcoming lunar eclipse that should be visible in North America on the night of January 20th.

click each image for the moon experiment simulation. Images by Lloyd and James Kaufman, original stereogram photography by Ansen Seale.

Listen to this program in RealAudio!

Guests:

Elizabeth Brannon
Department of Psychology
Columbia University
Assistant Professor
Center for Cognitive Neuroscience
Duke University
Durham, North Carolina

Lloyd Kaufman
Professor Emeritus, Psychology
New York University
Senior Scientist
Long Island University
Brookville, New York

James Kaufman
Physicist
Manager of Advanced Materials for Technology and Storage
IBM's Almaden Research Center
San Jose, California

Joe Rao
Lecturer
American Museum-Hayden Planetarium
"Skywatch" Columnist
New York Times
Meteorologist
News 12 Network
Westchester, New York

Books/Articles Discussed:

"Representation of the Numerosities 1-9 by Rhesus Macaques," Elizabeth M. Brannon and Herbert S. Terrance, Journal of Experimental Psychology: Animal Behavior Process, Vol. 26, No. 1.   "Explaining the Moon Illusion," by Lloyd and James H. Kaufman. Proceedings of the National Academy of Sciences, Januar 4, 2000.

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Related Links:

ABCNews.com: Monkeys Show Number Sense
CNN - Monkeys can count, new study finds

Father-son scientists confirm why horizon moon appears larger
A rebuttal / alternate theory from Don McCready, Psychology Department, U. Wisconsisn-Whitewater
Moon Illusion Stereogram Demonstration - moon at horizon
Moon Illusion Stereogram Demonstratio - moon at zenith
Ponzo perspective illusion

 

Catalog of Lunar Eclipses
Lunar Eclipse Computer
Lunar Eclipse Photo Gallery

This segment produced by:
Karin Vergoth
Web producer:
Charles Bergquist