GOING NOWHERE FAST
running in place
120 by Nicole Wetsman / illustration by Brown Bird Design by Claire Maldarelli
BACK IN THE ’9 0 S, ADAR PELAH WAS
studying vision at the University of Cam-
bridge when he noticed something funny at
the gym: For the first few minutes after step-
ping off a treadmill, he felt like he was moving
much faster than he actually was. Pelah docu-
mented his observation in a 1996 paper.
Since then, studies have tested many so-
called treadmill illusions, including this one:
Run on the machine for at least 10 minutes,
step off, then have a friend blindfold you. Try
to walk in place, and you’ll run forward instead.
While you’re on the treadmill, your body
is moving, but the world isn’t shifting past
you like it does when you’re striding on solid
ground. You end up with zero optic flow—the
motion of the visual world as you move. Once
you step off the machine, the universe moves
with you again. With positive optic flow sud-
denly back, your brain vastly underestimates
the speed at which your surrounding visual
field should be moving, creating a feeling of
acceleration, Pelah says. If blindfolded, you
move forward while attempting to stay in
place because your body still thinks that for-
ward motion keeps you stationary. It takes a
few minutes for things to recalibrate.
“It’s a multisensory illusion,” Pelah says.
“You have to be controlling your muscles at
the same time as you’re experiencing visual
information.” Put people in a wheelchair af-
ter a workout, and they don’t notice anything
strange if wheeled around. The documen-
tation of the shift—and shift back—helped
scientists realize the intimate interface that
exists between the visual and motor systems.
If you frequent the treadmill often, your
body becomes conditioned to the shift, and
the effect will stop. So if you need an explana-
tion for irregular gym attendance, wanting to
experience the illusion is a creative excuse.A TANGLED WEBthere’s only
one way out
ALL ROADS MIGHT LEAD
to Rome, but some destinations are
accessible by only a single route.
Practice your logical reasoning with
these path puzzles (instructions be-
low), a concept originally created by
mathematician Roderick Kimball.[1]
Instructions:
Each grid has two openings, and your
goal is to find the path between them.
The digits on the outside are both clues
and strict rules: They represent the
number of square cells the path travels
through in each corresponding column
or row. If there’s no number, the trail
can pass through an unconstrained
number of cells. Always, the path can
pass through each square just once.
(Use a pencil; answers on page 122.)[2]
HEAD TRIP
[1]2 4 2 5 5 2334442[2]224
2
22332[3]4 6 5 4 6 5662564