ILLUSIONS
Said’s illusion (right) depicts rows of red and
blue parallel vertical lines, seemingly arranged in
undulating pinkish and bluish stripes. In fact, the
waves are illusory because the vertical lines that
make up the horizontal stripes all have identical
lengths—meaning that each apparently curva-
ceous band is actually perfectly straight (top
right). The pastel shades inside the stripes are
also misperceptions: the background behind both
the red and the blue lines is flawlessly white. The
deceptive coloration is caused by a perceptual
phenomenon known as neon color spreading,
first described in the 1970s.
The mechanisms of the Müller-Lyer illusion
(and of its successors) are still debated among
researchers. One potential explanation, first
proposed by psychologist Richard Gregory, is
that our visual systems have learned that, accord-
ing to the laws of perspective, converging angles
(such as the arrowheads) indicate objects that
are close to us, whereas diverging angles (such
as the arrow tails) indicate objects that are far
away. Many other geometric illusions “involve
V-shaped lines,” Sarcone has pointed out, includ-
ing the Zöllner illusion, the Ponzo illusion and
Sander’s parallelogram, and they might share
a common basis.
Sarcone’s variant of the Müller-Lyer illusion
came about serendipitously. The artist had de-
vised a hands-on interactive exhibit consisting of
a metal board featuring a line with three red dots:
one dot in the middle of the line and two dots
at each end. To Sarcone’s surprise and delight,
many children “played nonstop with the thin
revolving hands of the exhibit, mesmerized by the
illusory effect.”
As for Said’s version of the effect, chance
played a role there as well. “My wife sent me theSarcone illusion—she thought it was very effec-
tive,” he explained. “I had some free time that day
because I’m between jobs, so I thought it might
be fun to play with it.” CHRIS SAID; DISTORTED STRIPES, MODIFIED FROM @GSARCONE