SHAPE-SHIFTER
try holding
this pattern
118 FALL 2019 • POPSCI.COM by Sara Kiley Watson
SOMETIMES THE FARTHER AWAY YOU
are from something, the clearer it is. At a
distance, you can tell that the pattern in the
center of this image differs slightly from the
design around it. But bring the page close to
your face, and one pattern appears to over-
take the other, making the once-disparate
motifs suddenly match.
Known as the uniformity illusion, which
University of Amsterdam assistant profes-
sor Yair Pinto first described in 2016, this
sleight takes advantage of the way we gather
information through our eyeballs.
In the center of the eye sits a tiny pit
known as the fovea. It contains a high
density of retinal cones, which provide a
detailed and colorful impression of the
objects directly in front of us. By contrast,
images at the edge of our gaze are perceived
by peripheral vision, which receives infor-
mation primarily from rods that are worse
than cones at detecting shapes and colors.
This outlying vision is always pretty weak.But it becomes increasingly unreliable the
closer the eye gets to a scene. That might ex-
plain why we can make out the shapes OK
from afar, but when we stick our faces too
close to the page, things get muddled and
the brain must make a judgment call. Since
the fovea is usually more dependable, we as-
sume whatever’s going on along the edges is
an “input error,” Pinto says, and try to match
every design to the one in the center.
This works with all sorts of visual alter-
ations. If the inside pattern is clear but the
outer one is blurry, the uniformity illusion
can cause the whole image to appear per-
fectly crystalline. The same is true not just for
shapes, but also for mismatched text, altered
orientation, and even changes in an image’s
density—look too close, and the outer pat-
tern will match whatever is in the inside. No
matter how weird things get, the brain will
rely on the best signal it has, Pinto says. That
doesn’t always guarantee the correct answer
(clearly). So it’s best to get some perspective.HEAD TRIP
BASED^ONTHE^ WORK^ OF^ MARTEOTTEN,^ YAIRPINTO,CHRISL.E.^PAFFEN,^ ANIL^ K.^ S
ETH,ANDRYOTA^ KANAI