This document has been archived.

Skip To Content Skip To Left Navigation
NSF Logo Search GraphicGuide To Programs GraphicImage Library GraphicSite Map GraphicHelp GraphicPrivacy Policy Graphic
OLPA Header Graphic

News Tip


***Halloween Edition***
October 30, 2002

For more information on these science news and feature story tips, please contact the public information officer at the end of each item at (703) 292-8070. Editor: Josh Chamot

Tricks of the Trade - The Science of Illusion

Illusions are designed to fool the mind, but behind every illusion, there is an explanation grounded in rational thought. From optics to psychology, magicians take advantage of science, culture, perception, and the art of performance to convince an audience that seeing is believing.

"Magic: The Science of Illusion," a California Science Center in Los Angeles traveling exhibition, explores these themes as it traverses the country. Supported by NSF, the Science Museum Exhibition Collaborative and others, the Center worked with magicians to design a series of hands-on activities and displays where guests can both experience magic and go "backstage" to see how the magic was done.

To maintain the secrecy of standard tricks, magic consultants -Penn & Teller, Goldfinger & Dove, Max Maven, and Jade - devised four illusions specifically for the exhibition: a disembodied head, a levitating chair, a mind-reading illusion, and transformation of a lightweight box into an impossibly heavy object.

In addition to the main illusions, a live stage hosts magic shows, and several displays feature history, take-home tricks, and artifacts, including handcuffs worn by Harry Houdini.

The exhibition will be at the Center of Science and History in Columbus, Ohio through February 23, 2003, after which the show will travel to Illinois, Massachusetts, New Jersey, and other states.

For more resources (and illusions to do at home), see the "Magic: The Science of Illusion" website:

Top of Page

"Moon Illusion" Still Confounds Scientists

scene of owl perched in tree; caption is below
Scene of owl perched in tree silhouetted against full moon low to the horizon.
Credit: Kirk Woellert/NSF
Select image for a larger version.
(Size: 30.1kb)

Larger versions (Total Size: 776KB) of all images from this document

 Note About Images

Walking along an open road on a clear, cool, windy Halloween evening, you notice the sun as it sets and the sky turning dark. Suddenly, you feel a presence. You turn sharply. Over the horizon, a large yellowish ball appears. Has Halloween come a-haunting?

No, it's only the moon. But, why does it look so huge?

We know the moon disc is the same size whether on the horizon or high in the sky. The larger horizon moon is an illusion. The phenomenon has been known to astronomers since before the second century A.D., yet scientists still debate the possible reasons for this "moon illusion."

Lloyd Kaufman, a Long Island University research scientist and retired New York University professor of psychology and neuroscience, has teamed up with his son, physicist James Kaufman of IBM, in new research for the National Science Foundation (NSF). The pair will test the "apparent distance" theory, determining whether or not perceived distance is linked with physical distance.

"We simply at this point do not know how perceptual distance varies with physical distance, but we feel that solving this problem can lead to new designs for safety-related devices and road and transportation system design, including vehicular control devices and visual guidance controls for aircraft," said Kaufman.

Maybe this knowledge will even provide comfort during a walk on a dark, cold, windy Halloween night. [Bill Noxon]

Top of Page

Tiger Moths Use Sonic Defense to Trick Bats

As a bat zips through the night sky, it sends out high-pitched squeaks, bouncing sound waves off of objects and unsuspecting prey. While most insect victims would have trouble fighting back, many dive and loop to avoid enemies, and some have the added advantage of being poisonous. Yet, in the dark, the bright warning colors of most toxic insects are lost on predators. Now, some researchers suspect one type of moth may have a way of effectively broadcasting its toxicity -- the insect produces high-pitched sounds of its own.

Tiger moths have a special clicker called a tymbal built into their thorax. When they fly, the moths click their tymbal to produce a distinct sound that seems to keep bats at bay. Scientists have proposed a few reasons for the tymbal's success, ranging from its potential to startle a bat to its possible role as a "jammer" that garbles the bats' hunting squeaks.

NSF researchers William Conner and Nickolay Hristov of Wake Forest University in North Carolina have found preliminary evidence that the tymbal may actually warn the bats: "I'm a tiger moth and I'm toxic." The bat may recognize the clicks from the 11,000 tiger moth species, learning to avoid the critters after an initial bout of food poisoning.

Next summer, Conner's team will take the research to the Ecology Summer Day Camp at Archbold Biological Station in Lake Placid, Florida. In addition to their summer of field activities, the kids will test out a new "Bats and Bugs" website that includes recorded bat sounds and videos of the in-flight battles. [Josh Chamot]

a big brown bat approaches a wax moth; caption is below
A big brown bat (Eptesicus fuscus) approaches a wax moth (Galleria mellonella), which serves as the control species for the studies of the tiger moths. The moth is only "semi-tethered," allowing it the mobility to fly evasively.
Photo credit: William Conner and Nickolay Hristov, Wake Forest University.
Select image for a larger version
(Size: 289KB)

the big brown bat is poised to scoop the wax moth; caption is below
The big brown bat is poised to scoop the wax moth into its tail membrane. The bat will then dip its head in to eat its prey.
Photo credit: William Conner and Nickolay Hristov, Wake Forest University.
Select image for a larger version
(File Size: 229KB)

an infrared camera captures detailed images; caption is below
The researchers use an infrared camera to capture high-speed (250 frames per second), detailed images of the predator-prey interaction in three dimensions.
Photo credit: William Conner and Nickolay Hristov, Wake Forest University.
Select image for a larger version
(File Size: 44KB)

Larger versions (Total Size: 776KB) of all images from this document

 Note About Images

Bat Capture Moth.wav: The audio recording features the high-pitched cries of a big brown bat using echolocation to chase a moth in William Conner's laboratory. The slowly repeating cries are from the bat's "search phase," faster cries are from the "approach phase," and the final, very rapid pattern is called the "terminal buzz" - the point at which the bat captures its prey. The ultrasound clicks are actually too high-pitched for humans to hear, so the researchers slowed the recording to 1/25 of its original speed, lowering the pitch and lengthening the duration of the squeaks. The original hunt took only 5 seconds to record.

Top of Page

Is That the Great Pumpkin?

Linus Van Pelt spent every Halloween night sitting in the pumpkin patch waiting to catch a glimpse of "The Great Pumpkin." Linus might soon be successful if he keeps his eyes pealed on the skies over Amherst, Massachusetts. There, he may catch a glimpse of a Langrangian balloon, a 30-foot-diameter, floating structure shaped like a giant pumpkin.

The pumpkin balloon, which scientists are now building, gets its shape from ribbing in its envelope. The device will be used to conduct atmospheric sounding and includes controls to regulate its buoyancy, unlike conventional balloons, which achieve and sustain lift by being lighter than air. The Langrangian balloon will lift until a determined altitude is achieved, then its controls will establish and maintain it as a neutral object in the air. This allows its instrument payload to measure and track vertical air motion and provides a frame of reference for measurement of temperature, pressure, humidity, ozone, and other trace gases. The measurements are needed to observe the histories of air parcels as they undergo photochemical and cloud physical processes in the high atmosphere. The NSF-funded project is a collaborative effort of the University of Massachusetts Amherst and Smith College's Pickering Engineering Program. [Manny Van Pelt (no relation)]


Pumpkin balloon

The pumpkin balloon, which scientists are now building, will be used to conduct atmospheric measurement of temperature, pressure, humidity, ozone, and other trace gases.
Select image for a larger version
(File Size: 155KB)

Larger versions (Total Size: 776KB) of all images from this document

 Note About Images

Top of Page



National Science Foundation
Office of Legislative and Public Affairs
4201 Wilson Boulevard
Arlington, Virginia 22230, USA
Tel: 703-292-8070
FIRS: 800-877-8339 | TDD: 703-292-5090

NSF Logo Graphic