Download visual perception

An Introduction to Visual
Perception!
What is visual perception?
“visual perception is the end product of vision”
It can be described as the way the brain interprets what
the eyes see.
THE BRAIN
•The brain receives information from the
retina, then using a hierarchical method
processes this information using different
parts of the brain e.g. lateral geniculate
nucleus and the primary and secondary
visual cortex of the brain.
• The main problem with visual perception
is that it is not simply a translation of the
image seen by the retina, making it difficult
for scientists to explain what we actually
see.
• This can be altered by previous experiences.
• The Chairs theory
• It can effect the way you see a situation.
• The Taxi theory
• It is used in media to make you have the opinion of
someone that they want you to have.
• The Bad guys/good guys theory
Human Vision
• Human vision is not the only way the world is seen,
Animals see the world in different ways.
• some animals don’t even see the world but rely on
other senses e.g. bats and dolphins
• Flies have what’s known as composite eyes, a
TV run at 25 frames per second but to a fly this is
very slow.
• birds such as hawks can see up to 8 times
further than a human. The range of distance is
measured in dioptres, a child’s is 14, an old
persons is 1, however a diving bird’s vision is 50
dioptres.
• field of vision also is limited on a human to
between 160-240, where as a hare’s field of vision
is 360.
•Different creatures vary the amount of brain is
dedicated to vision, the octopus dedicates 50% to
sight but we still don’t know how other creatures
make sense of what there eyes see. No single
creature can see all what others can. We forget that
the human world of vision is only one such world.
Homo significans
The world is seen in different ways by different creatures, as humans
we put a large emphasis on visuals. We do not always believe our
eyes, we know that a pencil in a glass jar will look bent and that a
moon closer to the horizon will appear bigger and that there are such
things as optical illusions.
Humans as a species are driven by a desire to find meaning. This
relates to the title, because as humans we are all “homo significans”meaning makers.
This is proved with a few simple shapes and lines, that the mind
strives to find meaning in.
What do you see here:
Your more likely to see five pairs close together than 4 pairs more
spaced with a line either side spare. We do this because the brain puts
the closer objects together.
Hermann Von Helmholtz
•Hermann Von Helmholtz, seen as the
founder of visual perception studies
believed vision was a form of unconscious
inference, (Inference is the act or process
of deriving a conclusion based solely on
what one already knows)
•Two well known assumptions are that
light comes from above and that objects
are viewed from above, not below.
•Visual illusions are where this process
goes wrong e.g…
The Scintillating grid illusion

Black spots will seem
to appear very quickly
at the intersections.
Optical illusion


Focus on the black
dot and move your
head back and forth
This creates the
illusion that two
circles are moving
Gestalt Theory
o
o
o
The Gestalt Theory originally came about in the 1890’s.
Gestalt is German for “Shape/Form/Likeness”
There are 3 main Gestalt psychologists:
Max Wertheimer (Is credited as the founder of the movement
of Gestalt Psychology)
o Wolfgang Köhler
o Kurt Koffka
o
o
o
The concept of Gestalts Psychology was originally
foundered by an Austrian psychologist called Christian
Freiherr von Ehrenfels
The major problem with the Gestalt laws and principles are
that they are mainly descriptive and not explanatory.
Gestalt Theory
The Gestalt Principles can be split into 3 groups:
Figure and Ground
Similarity, Proximity, Common Fate and Good Continuity
• Closure, Area and Symmetry
•
•
Gestalt Theory
FIGURE AND GROUND
Figure and Ground explains how we put different elements
together to make one scene or a whole image.
o
o
“Figure” is the more dominant shape.
“Ground” can be referred to as the Background.
What do you see this image as?
o
A Goblet on a Black background
o
A Black Silhouetted Profile on a White background.
Once you have identified the figure, the rest of the
image becomes the ground.
The most famous “Figure and
Ground” image is the one by
the Danish psychologist
Edgar Rubin.
Camouflage is most likely a breakdown in the figure ground
the dominant shape is so much like the ground it
disappears from view.
Can you spot the bird?
perception. When
Gestalt Theory
SIMILARITY
When we have similar objects of size, shape and colour again we
form groups.
This image is grouped together
by colours
Squares and Circles
PROXIMITY
Gestalt Theory
When objects which are closer to each other we tend to associate them
together to form groups.
You will see columns rather than
rows
You will see rows rather than
columns
Real life example. MTV Music awards.
We group this image into 2 parts, the
top left this shows us this is the MTV
music awards, and the bottom right
which groups together the sponsors of
the awards.
Gestalt Theory
COMMON FATE
Objects which are facing the same direction or appear to be travelling in
the same direction are usually grouped together.
The arrows which are pointing in a
common direction are usually grouped
together.
Again the lines facing upwards tend
to be grouped together.
CONTINUITY
Gestalt Theory
Seeing things as a whole is important however seeing in a whole is not
necessarily what we are meant to see.
What do you see here?
CONTINUITY
Gestalt Theory
Seeing things as a whole is important however seeing in a whole is not
necessarily what we are meant to see.
What do you see here?
Well there are two answers.
Continuity makes us see 2 lines crossing
BUT
Is it actually 4 lines, A-O, O-D, C-O and O-B
CLOSURE
Gestalt Theory
If we have a large pattern with missing components we tend to fill in the missing
parts to create the image we actually see.
A.
B.
C.
D.
When joined you can see a triangle.
This image can be seen as an “S” shape
Looking at this object we tend to form a 3D sphere.
If you look closely this image looks like the snake.
These two images can be closed
together to form a circle and a square.
Real Life example. WWF Logo / IBM Logo
This image creates the
illusion of 3 letters, I, B and M
This image can be closed
to make a panda
AREA
Gestalt Theory
This principle shows us that when areas are overlapping, the smallest area is seen
as the figure and the larger is the ground. When we look at this object, we
see this as one object on top of the another instead of a hole in the larger area.
We can reverse this perception by adding shading.
On a black larger object we now see is hole.
Gestalt Theory
SYMMETRY
Objects which are symmetrical, we are more likely to group
them together.
This principle also describes looking at an image and perceiving it as a
whole figure instead of it’s individual parts.
What do you see here?
2 Overlapping diamonds
2 Large diamonds and 1 small diamond
2 L-Shapes and 1 diamonds
If you are viewing this according to the principle you are
Most likely viewing this as 2 overlapping diamonds.
Gestalt Views In Psychology
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Gestalt psychologist’s believe the problem of visual
perception should be considered as a whole.
Max Wertheimer believes that thinking happens in two
ways:



Productive thinking- is solving a problem with insight.
Reproductive thinking-is solving a problem with previous
experiences and what is already known.
Other Gestalts psychologist such as Perkins believes
insight deals with three processes:
1) Unconscious leap in thinking.
2) The increased amount of speed in mental processing.
3) The amount of short-circuiting which occurs in normal
reasoning.
Conclusion

Vision is not necessarily what we see but
how our brain interprets the world around
us, our own experiences can shape how
we perceive this world.
“Seeing is believing”
Any Questions?
Watch the black cross
To see the green circle