Illusions of Seeing: Exploring the World of Visual Perception

283 Pages·2021·17.094 MB·English

by  Thomas Ditzinger

Thomas Ditzinger
Illusions
of Seeing
Exploring the World of Visual Perception
Illusions of Seeing
Thomas Ditzinger
Illusions of Seeing
Exploring the World of Visual Perception
Thomas Ditzinger
Reichartshausen, Germany
ISBN 978-3-030-63634-0 ISBN 978-3-030-63635-7 (eBook)
https://doi.org/10.1007/978-3-030-63635-7
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For Leonie, the star of my eye
Foreword
Thomas Ditzinger takes us on a fascinating tour through the visual world of illu-
sions. Light is the stimulus for the eye, but the complex processes that follow stimu-
lation are illuminated by the study of illusions. The book not only presents a great
variety of visual illusions (often in color), but it also links them to the physiological
process in the visual system and to their subtle use by artists. Illusions can make us
smile and wonder at the sophistication of seeing, and Ditzinger does not lose con-
tact with the fun of the phenomena that he so clearly displays.
Psychology Department Nick Wade
University of Dundee
Dundee, Scotland, UK
vii
Preface
We live in a fantastic, fascinating, wonderful world. Each one of us is an important
piece of the puzzle in this world and tries to get along in it as well as possible. To do
this we, use our senses, which enable us to simultaneously perceive an enormous
amount of environmental stimuli and information. The human system of perception
has developed in the course of evolution in close interaction with its environement.
Therefore, it is no wonder that our brain and its perceptual apparatus became an
image of its environment—with similar fantastic, fascinating, wonderful character-
istics. You can see this for yourself in this book.
In order to accomplish these enormous perceptual achievements, a highly com-
plex self-organized configuration of the brain is required. Our brain consists of the
unimaginable number of at least 100,000,000,000 nerve cells, the neurons. That is
almost 20 times as much as the current number of the world’s population! Together
with the glial cells, whose exact function has not yet been fully clarified, the neu-
rons form the basic building blocks of our human brain. On average, each neuron
has about 1000–10,000 connections to other nerve cells. The connection runs
through strongly branched axons with a total number of at least 100–1000 trillions
in American naming or billions in British naming (a 1 with 14–15 zeros)—which is
already in the range of the world population of ants on earth. If one added the length
of all these branches of communication, it is estimated that the total distance would
be an almost unbelievable half to one million kilometers. That would correspond to
a telephone cable about 25 times the distance from the earth to the moon and back
again, wound up in our brain!
Vision is perhaps the most important innovation of evolution for the development
of the human brain and perception. Approximately 60% of all environmental expe-
riences reach our brain through the eye. That is why vision is also regarded as the
key to understanding our brain. The main aim of this book is to get to know and
appreciate the wonderful abilities of our visual apparatus. It will become clear that
our visual and perceptual apparatus is wonderfully capable of presenting the most
contradictory and complicated environmental impressions very simply in concise
forms. Let yourself be taken on a journey of discovery through your own percep-
tion! Because of the special destination, you do not only read in a book, but you
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x Preface
read—and see—mainly in yourself. This book serves as your guide on this fantastic
adventure. Similar to a holiday trip, there will be eyes of relaxation, but also highly
impressive natural beauties and interesting discoveries to experience.
Again and again it will become clear that our perception can be characterized by
a few simple basic characteristics: It is pragmatic and always strives for the simplest
solution (one could also say it is “lazy”), and it has a powerful wealth of prior
knowledge and prejudices learned from evolution. You will see that the most impres-
sive illusions of seeing always take place when these basic characteristics come into
conflict with each other. You will recognize the important role of a third character-
istic of your perception: It is imaginative and meaningful and accepts compro-
mises—and sometimes cheats a little.
This adventure guide for the eyes presents to you a multitude of well-known and
new optical illusions, illusions, and fantastic images. Each of these travel experi-
ences will provide you with a new way to understand your own perception.
In the first journey you will learn something about the nature of light and its
perception by the human eye. You can also get to know sheep that not only bleat and
eat grass, but also know the laws of vision. You will learn some important funda-
mentals of Gestalt psychology and the essential laws of human perception.
The second journey takes you into the magic world of geometric optical illu-
sions. You will be amazed at how easy it is to lead your brain up the garden path
with simple line drawings. Thus, straight lines suddenly appear tilted, curved, or of
different lengths.
The third journey is about the perception of forms, brightness, and transparency,
and their interaction. You will realize that the perception of form and brightness of
a figure depends decisively on the form and brightness of the background. For
example, you can see two identical suns, which are perceived completely differ-
ently, and experience what “brightness contrast enhancement” is all about.
The fourth journey is dedicated to ambiguous perception. After a short viewing
time, you see images that suddenly look completely different than before and come
to life. Cubes that jump like wild in space, or drawings of young people that look
just like their own grandparents, will fascinate you. These ambivalent images are
used, among other things, to measure very individual “fingerprints of your mind.”
The fifth journey into color vision tells you why all cats are grey at night, why
the sky is blue, why day vision differs from night vision and what complementary
colors, and afterimages are all about. And you can meet a dog whose picture wag-
gles its tail in front of your eyes. Also read why men are much more color-blind than
women, and why the color blue is something very special.
During the sixth journey into spatial vision you can learn why you have two eyes.
You can penetrate into deeper perceptual dimensions and experience various meth-
ods of depth perception such as the Pulfrich effect, the red-green anaglyph tech-
nique, pairs of random dot images, and autostereograms.
The seventh journey involves seeing of movement and its interaction with color,
form, and spatial depth. We transform a solid pencil into rubber and black and white
images into color and set stationary images in motion depending on their color.
Preface xi
The eighth journey takes you into the everyday life of our completely normal
life. We are in the supermarket, the dentist, the fashion house, looking for well-
camouflaged hidden animals, in shadow and light. You will be amazed how many
small and big miracles and illusions even the greyest everyday life consists of, if
you only look with open eyes. And sometimes our daily life also brings leisure and
sports or a holiday. Therefore, we also visit a football stadium, a ski slope, San
Francisco, and Loch Ness.
The upcoming trips will take you from the polar star to Jupiter via Freiburg back
to the moon and the sea, to the green meadow of the local honeybee, to Venice
Beach and to a nearby motorway bridge.
You can travel all these distances with the most fascinating, cheapest, and most
comfortable known means of transport: Your own thoughts. The entire route ahead
of you, from the infinite expanses of the universe to the café around the corner, fits
exactly into this book and into your head—just like the rolled out “telephone cable”
of the aforementioned nerve connections.
I promise you a lot of fun and things to marvel on all these paths!
Reichartshausen, Germany Thomas Ditzinger
Contents
1 First Journey: Light, Perception, and the Laws of Seeing . . . . . . . . . 1
1.1 Human Perception . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
1.2 Light and Vision . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2
1.3 The Senses Strive for Order . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
1.3.1 A Puzzle Animal . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
1.3.2 Gestalt Psychology. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
1.4 The Sheep and the Laws of Sight . . . . . . . . . . . . . . . . . . . . . . . . . . 9
1.4.1 The Law of Conciseness . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
1.4.2 The Law of Similarity . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
1.4.3 The Law of Proximity . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
1.4.4 The Law of Good Continuation . . . . . . . . . . . . . . . . . . . . . . 14
1.4.5 The Law of Unity . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15
1.4.6 The Law of Experience . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15
2 S econd Journey: The Geometrical-Optical Illusions . . . . . . . . . . . . . . 17
2.1 E rrors of the Senses . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17
2.2 T he Müller-Lyer Deception, Part 1 . . . . . . . . . . . . . . . . . . . . . . . . . 18
2.3 T he Constancy of Size: An Important Basis for Perception . . . . . . 19
2.4 T he Müller-Lyer Deception, Part 2 . . . . . . . . . . . . . . . . . . . . . . . . . 20
2.5 T he Poggendorff Deception . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24
2.6 T he Sander Deception . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26
2.7 H ering’s Deception . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26
2.8 T he Zöllner Deception . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28
2.9 T he Tilting Aftereffect . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29
2.10 T he Fraser Deception . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30
2.11 T he Vertical Deception . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30
2.12 T -Shirts, Cross- and Longitudinal-Striped . . . . . . . . . . . . . . . . . . . . 33
2.13 T he Oppel-Kundt Deception . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33
2.14 T he Moon Deception . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34
2.15 T he Titchener Deception . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35
2.16 The Ebbinghaus Deception . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35
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