This article focuses on an illusion due to our perceptions regarding competing coordinate systems or frames. I share an interesting anecdote and then explain aspects of its origin, referencing other similar illusions in the literature. Although it is difficult to experience the phenomenon without visiting the hill, I have some suggestions to physics educators for their classrooms at the end of the study.

1.
I.
Bianchi
and
U.
Savardi
, “
What fits into a mirror: Naïve beliefs about the field of view
,”
J. Exp. Psychol. Hum. Percept. Perform.
38
,
1144
1158
(
2012
).
2.
M.
Ellenstein
, “
Magic and physics
,”
Phys. Teach.
20
,
104
106
(
Feb.
1982
).
3.
R. D.
Edge
, and
E. R.
Jones
, “
Optical illusions
,”
Phys. Teach.
22
,
591
593
(
Dec.
1984
).
4.
M. R.
Avett
,
A.
Diehl
,
L. P.
Scheuneman
, and
D. G.
Haase
, “
Illusions for motion detectors
,”
Phys. Teach.
35
,
174
175
(
March
1997
).
5.
P.
Gibbs
, “
I know a place where things seem to roll uphill. How does it work?
John Baez’s homepage
, http://math.ucr.edu/home/baez/physics/General/roll-uphill.html, accessed August 29, 2015.
6.
P.
Bressan
,
L.
Garlaschelli
, and
M.
Barracano
, “
Antigravity hills are visual illusions
,”
Psychol. Sci.
14
,
441
449
(
2003
).
7.
H. E.
Ross
, “
Foreshortening affects both uphill and downhill slope perception at far distances
,”
Behav. Brain Sci.
36
,
563
564
(
2013
).
8.
Z.
Li
and
F. H.
Durgin
, “
Downhill slopes look shallower from the edge
,”
J. Vision
9
,
1
15
(
2015
).
9.
P. M.
Jaf
, “
Optical illusion and the magnetic hills in Koya Region
,”
J. Kirkuk Univ. Sci. Studies
4
,
40
47
(
2009
).
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