James Lu
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Biography:
My name is James Lu, a sophomore in Electrical Engineering. Some of the reasons I
chose to write my article on optical illusions are that I conducted experiments on the subject in
high school and that my father was involved in research related to illusions. Furthermore, I like
to play video games and one game-related product that caught my attention was the Oculus
Rift, which uses illusions to create virtual reality. By combining these three topics, I came up
with the basic idea for my paper.
Abstract:
Optical illusions are a commonplace phenomenon that tricks people into seeing
something that does not exist. This has major connotations given how most people rely
primarily on vision to perceive the world, yet there is little coverage on the topic. For example,
the curveball in baseball is actually an optical illusion. Though the ball’s path actually does
curve slightly, the ball’s supposed changes in trajectory are actually because of an illusion.
Another example of optical illusions relates to how fast an object is moving. Depending on a
number of factors, objects may move faster than they appear which can lead to incidents when
involving large high-speed objects like trains or trucks. This is a possible factor in vehicular
incidents that is completely overlooked. By taking advantage of optical illusions, people have
created numerous projects, like the Oculus Rift. Currently in development, the Oculus Rift
immerses the user into virtual reality through illusions. All of these examples are only a fraction
of what people have come up with. By studying everyday phenomena like optical illusions,
people can think up endless ideas, which can improve society.
Keywords: Virtual Reality, Optical Illusions, Baseball, Vehicular Incidents
Multimedia:
Break of the Curveball Illusion by Arthur Shapiro. This is a flash animation that demonstrates
the curveball illusion and it can be adjusted to show how speed, rotation, and orientation affect
the illusion. (http://illusionoftheyear.com/2009/the-break-of-the-curveball/)
Static Motion Illusion. This is a completely still image, but due to the shapes and colors in the
image, it appears as if it is actually moving. (http://list25.com/25-incredible-opticalillusions/?view=all, Image 4)
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Illusions in Everyday Life
Through a myriad of ways, optical illusions take advantage of the flaws in human vision
to trick our eyes into seeing nonexistent things or completely misjudging what we see. One
everyday example of this is in movie theaters, through 3-D movies. By combining split images
and 3-D glasses, movies seem to pop out of the screens. Other examples include still images
that seem to move or impossible objects, like the blivet,
which is rectangular at one end and cylindrical at the other
([1]: Image 21). Optical illusions, though generally not
seen for what they are, are in fact prevalent in everyday
life. Some positive examples of optical illusions include the
blivet or devil’s fork
curveball in baseball and the virtual reality device, Oculus Rift. However, there are also
negative examples, such as the misperception of the speed of large and distant vehicles. By
taking advantage of the positive uses, optical illusions can be used to enhance the everyday
lives of people.
One extremely prevalent yet completely unnoticed optical illusion is the curveball. A
type of pitch in baseball that involves putting spin on the ball, the curveball is a popular and
more advanced technique used in professional baseball. In particular, the curveball is used to
throw batters off because of its confusing trajectory. Many batters report that “the flight of the
ball undergoes a dramatic and nearly discontinuous shift in position as the ball nears home
plate” (Transitions between Central and Peripheral Vision), causing the ball to “jump” in their
vision. According to the physics of kinematics, the ball will follow a parabolic curve due to the
spin of the ball. The trajectory of the ball should not change as it approaches home plate. Yet,
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the ball seems to do it anyway, completely ignoring physics. One hypothesis that has been
presented to remedy this disregard to physics is that the “jump” in a curveball isn’t real; instead
this shift in position is actually due to the batter’s misperception. According to research article
published in PLOS ONE, a batter watching a curveball will watch the ball with their central vision
for about two-thirds of the balls flight, then shift over to peripheral vision until the ball is
approximately five feet or so away. Because the batter shifts from peripheral to central vision
in the last few feet that the ball travels, they see a “jump” in the location of the ball (Transitions
between Central and Peripheral Vision). Because the human visual system gives higher priority
to central vision, there is a difference in resolution
of images. While central vision is akin to a high
quality filmmaking camera, peripheral vision is
similar to a more commercially available, lower
quality camera. The differences between the two
Actual Trajectory vs. Perceived Trajectory [2]
are immediately visible in one visual from the
authors of the article, where a spinning disk shows a difference in perception when one
compares their central and peripheral vision [5]. Thus, by combining the difference in quality
between central and peripheral vision with the spin of the ball, batters are deceived by their
own visual system into seeing the ball suddenly shift position.
Though some illusions are harmless and used to great effect, others can cause great
harm. Two examples of this are two illusions that cause people to misjudge the speed of
objects. The first illusion is one that causes errors in speed perception through distance. In
“The Speed Illusion of Trains”, Anthony Chen and I hypothesize and test the theory that objects
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at a distance seem to be moving slowly in comparison to closer objects that are actually moving
at the same speed. Through experiments that compare the speed of far and near objects, we
found that “though extreme differences of speed are easily recognizable, if the speeds are
similar, the objects appear to have the same
speed even though the farther one is
approximately 1.3 times faster” (Speed Illusion
of Trains). Essentially, if an object is moving at
60 miles per hour, the view will perceive the
[4]
object as moving at approximately 46.2 miles per hour. Though it may seem trivial on a smaller
scale, this difference between perceived and actual speed is huge when it is applied to vehicles
and other high-speed objects. Furthermore, this misperception of speed is only compounded
by a second illusion that causes errors in speed perception through size. In a research paper
from the University of Waikato, New Zealand, it is stated that “humans perceive large objects
(e.g. trains, trucks, buses) as moving more slowly than smaller objects (e.g. motorcars)
travelling at the same speed” (Illusory size-speed bias). When combining this size-speed illusion
with the previous distance-speed illusion, there is a major effect when judging the speeds of
incoming, large objects like trains, trucks, or vehicles. There have been numerous train-car
collisions caused because drivers incorrectly judge the speed of an incoming train and believe
that they can safely cross at railway crossings in time. However, due to the illusion that the
large train is moving more slowly, drivers instead are unable to cross before the train arrives,
resulting in collisions. Railway and vehicular incidents happen across the globe all the time; in
the past ten years the incidence rate of vehicle collisions has not decreased. In 2008 alone,
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there were 468 vehicle related deaths in Europe and 220 deaths in the United States, with a
total of 2248 collisions (Illusory size-speed bias). Yet despite all of these incidents being in the
news, there have been little to no mentions of possible causes. These size-speed and distancespeed illusions are misleading people into incidents worldwide, but they still remain out of the
public’s eye.
One way that optical illusions are being utilized is in the field of virtual reality. Though
several ways of creating virtual reality are currently being developed, one of the most
prominent is the Oculus Rift. First developed by Palmer Luckey at the University of Southern
California, the Oculus Rift is a head-mounted display that takes advantage of a high-definition
screen, motion sensors, and two lenses to make the user feel like they are in a virtual world
([3]). The Rift gives the user a 110 degree field of view, significantly increasing the illusion that
the user is in a different world. Furthermore, because of
the motion sensors, the Oculus Rift will coordinate with
the user’s head motions and change their field of view
along with where the user is looking. Wherever the user
tilts their head or turns to look, the screen of the Rift will
compensate, as if the user was actually in the virtual world.
CEO of Nival using the Oculus Rift [3]
Because of the wide field of vision and simulation of human movements, the user uses optical
illusions to place themselves in a whole new world, determined by whatever software is being
run. Unlike the other examples of illusions given, the Oculus Rift creates an immersive illusion
that was deliberately designed for the purpose of advancing entertainment. Though the most
prominent use and development for this device is in the video game industry, it has a vast
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amount of potential outside gaming; virtual tours, movies, and video conferencing are just a
few examples. More than just being a well-designed optical illusion, the Oculus Rift is a product
that uses illusions as a means to achieve the long sought goal of virtual reality.
Optical illusions can be seen everywhere in daily life. Though completely unnoticed for
the vast majority of the history of baseball, the illusion of the curveball has been in use for an
incredible amount of time. Professional baseball pitchers have unintentionally used optical
illusions to fool opposing batters. Meanwhile, optical illusions are being put to use in virtual
reality, with devices like the Oculus Rift. The applications of virtual reality are limitless, from
gaming to video conferencing, all through optical illusions. Yet, negative optical illusions also
exist, as seen in people’s misperception of speed due to size and distance. By combining large
vehicles like trains or trucks with size-speed and distance-speed illusions, this leads to a large
number of drivers completely misjudging the speed of approaching vehicles. Because of this,
many drivers believe they can cross railroad crossings before trains or busses arrive, leading to
a large number of incidents worldwide. Optical illusions are just one of many things that occur
in everyday life and even a small amount of research has led to both revolutionary new ideas
and simple ways improve everyday life. There are many ignored phenomena that could be
used to our advantage, so it is up to us to think of ways they can be used for the betterment of
society.
James Lu
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Works Cited
[1] D. Pegg, “25 Incredible Optical Illusions,” List 25, http://list25.com/25-incredible-opticalillusions/?view=all
[2] A. Shapiro, Z.L. Lu, C.B. Huang, E. Knight, R. Ennis, “Transitions between Central and
Peripheral Vision Create Spatial/Temporal Distortions: A Hypothesis Concerning the Perceived
Break of the Curveball, PLOS One, http://www.plosone.org/article/info%3Adoi%2F10.1371%2
Fjournal.pone.0013296
[3] S. Parkin, “Can Oculus Rift Turn Virtual Reality Wonder into Commercial Reality?”
http://www.technologyreview.com/news/519801/can-oculus-rift-turn-virtual-wonder-intocommercial-reality/, 2013
[4] A. Chen, J. Lu, “The Speed Illusion of Trains” for Vision Society’s Best Illusion of the Year
Demo Night 2011, 2011
[5] A. Shapiro, Z.L. Lu, C.B. Huang, E. Knight, R. Ennis, “The Break of the Curveball” For Vision
Society’s Best Illusion of the Year Contest, 2009 First Place http://illusionoftheyear.com/
2009/the-break-of-the-curveball/
[6] H.E. Clark, J.A. Isler, R. B. Charlton, S.G. “Illusory Size-Speed Bias: Could this help explain
Motorist Collisions with Railway Trains and Other Large Vehicles?” http://acrs.org.au/files
/arsrpe/Paper%20151%20-%20Clark%20-%20Railway%20Level%20Crossings.pdf, School of
Psychology, Unversity of Waikato, Hamilton, New Zealand