Popular Science - USA (2020 - Spring)

is this the world’s

fi rst illusion?

THIS CARVED

ornament was fixed on

a hunting tool more than

14,000 years ago, but the

illusion remains. Con-

centrate on the higher

eye- shaped notch on the

left side, and a tusk curves

below it, revealing a mam-

moth. Stare at the one lower

down, and that pointed

tooth becomes a bison’s

horn as the beast bows its

head. You might recall a

similar 19th- century illus-

tration: It’s a duck until the

bird’s bill morphs into a

pair of rabbit’s ears.

The rabbit-duck is a

type of illusion called an

ambiguous figure, and

while we can’t know the an-

cient carver’s intent, this

prehistoric knickknack

is one too. According to

Kyle Mathewson, a cogni-

tive neuroscientist at the

University of Alberta, the

flip- flopping happens be-

cause the mammoth and

bison share the same basic

outlines. Your brain’s vi-

sual cortex makes sense of

this low-level information,

and then hands it off to a

set of high-level processing

neurons, which parses fea-

tures like fur or tusks. This

way, two different results

stem from the same set

of lines. Mammoth, bison;

tomato, tomahto.

BYTOM MCNAMARA LE

FT

TO

RI

GH

T:^

DU

NC

AN

C

AL

DW

EL

L;^

FR

OM

FL

IEG

EN

DE

BL

ÄT

TE

R,^

OC

TO

BE

R^2

3 ,^

18

92

DIVERSIFY YOUR PORTFOLIO WITH PRECIOUS METALS TODAY:

GOLD SILVER

164

00

O EACH

N

LY

19

99

O EACH

N

LY

©2020 U.S. Money Reserve. The markets for coins are unregulated. Prices can rise or fall and carry some risks. The company is not affi liated with the U.S. Government and the U.S. Mint. Past performance

of the coin or the market cannot predict future performance. Prices may be more or less based on current market conditions. Special offer is strictly limited to only one lifetime purchase of 10 below- or at-cost

gold coins and 20 below- or at-cost silver coins (regardless of price paid) per household, plus shipping and insurance ($15-$35for precious metals dealers. All calls recorded for quality assurance. 1/10-oz. coins enlarged to show detail. Offer void where prohibited. Offer valid for up to 30 days or while supplies last. Coin dates our choice.), and state sales tax where applicable. Minimum order of 5 coins. Price not valid

SPECIAL ARRANGEMENTS MADE FOR GOLD ORDERS OVER $50,000.

1-800-308-9452 VAULT CODE: PS19

OFFER VALID FOR 30 DAYS OR WHILE SUPPLIES LAST.

1/10-Ounce
U.S. Government-
Issued $5 Gold
American Eagles

1-Ounce

U.S. Government-

Issued $1 Silver

American Eagles

As one of America’s largest

gold distributors, U.S. Money

Reserve is offering special rock-

bottom pricing on offi cial U.S.

government-issued coins from

the U.S. Mint. For a limited time,

purchase American Eagles with

ZERO markup at incredible

below-cost prices. Call now!