Prof. Greg Francis
Gestalt Psychology
PSY 310
Greg Francis
Lecture 14
This is a real object!
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Wilhelm Wundt

Established the first true psychology laboratory in 1879
 University of Leipzig (Germany)

Tried to identify basic elements of
perception

Structuralism

Similar to approaches in chemistry/physics
 Find basic elements of matter (molecules)
 Find basic elements of molecules (atoms)
 Find basic elements of atoms (protons, electrons)
 Find basic elements of….

Along the way you learn about how the basic elements
combine to have different properties
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PSY 310: Sensory and Perceptual Processes
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Prof. Greg Francis
Structuralism

The basic idea is the perception is based on
sensations
 Look at the title of your textbook and this class!


Sensations are supposed to be simpler responses
to stimuli
Sensations are identified by introspection
 “Looking” inward to identify the basic elements of the
experience
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Structuralism

If you take a bite of an apple, you might describe its basic
sensations as
 Cold, sweet, crisp

It would be a mistake to refer to it as
 apple
Purdue University
PSY 310: Sensory and Perceptual Processes
2
Prof. Greg Francis
Structuralism

If you could do this for lots of people and lots of stimuli, you
might identify the basic sensory elements of many different
perceptual experiences

Scientific reductionism

It never really worked out
 Different people report different basic sensory elements
 No set of basic sensory elements seemed to cover lots of
different perceptual experiences

The goal of reduction is still a strong part of perception, but
not along these lines
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Other problems


Some percepts seem problematic for the
structuralist approach
In structuralism, percepts are built of up sensations
 So sensations must be necessary to produce percept


What about a stimulus like this?
What sensation contributes
to the perception of the
illusory contour?
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PSY 310: Sensory and Perceptual Processes
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Prof. Greg Francis
Other problems




Likewise, there are stimuli where presumably
sensations are being gathered, but they do not give
rise to a percept
Motion Induced Blindness movie
For that matter, one seems to get entirely new kinds
of perceptual experiences from some stimuli
Apparent motion (demo)
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Ambiguous stimuli

There are thousands of stimuli that can be interpreted in
different ways
 Presumably they produce the same sensations, but different
percepts
Purdue University
PSY 310: Sensory and Perceptual Processes
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Prof. Greg Francis
Ambiguous stimuli

There are thousands of stimuli that can be interpreted in
different ways
 Presumably they produce the same sensations, but different
percepts
 Find the man playing the flute
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Ambiguous stimuli

There are thousands of
stimuli that can be
interpreted in different ways
 Presumably they produce
the same sensations, but
different percepts

Find the Dutch girl
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PSY 310: Sensory and Perceptual Processes
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Prof. Greg Francis
Ambiguous stimuli

There are thousands of stimuli that can be interpreted in
different ways
 Presumably they produce the same sensations, but different
percepts

It’s not just clever drawings

Much of perception involves ambiguity
 More than you realize

Motion
 noWobbleGlobe.mov
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Gestalt Psychology

The structuralists recognized these kinds of problems for
their approach, but they thought one could eventually deal
with them

Other people advocated an entirely different approach

German scientists (Wertheimer, Koffka, Kohler)

Gestalt is a German word that roughly means “whole”

Gestalt psychologists suggested that understanding
perception could not be done by breaking it down into parts,
but by considering the whole experience
 The whole is different than the sum of its parts.

One task of perception is to identify how to organize different parts
of a visual scene
 How to identify objects?
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PSY 310: Sensory and Perceptual Processes
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Prof. Greg Francis
Perceptual organization

What about the image or the visual system allows you to correctly
group different parts of the scene into objects?
 Similarity: color, texture, orientation
 Position
 Familiarity

Gestalt “laws” of perceptual organization
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Similarity

Can isolate effects
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PSY 310: Sensory and Perceptual Processes
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Prof. Greg Francis
Position

Can isolate the effect
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Familiarity

Having seen this image before, your perceptual organization is
different than the first time
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PSY 310: Sensory and Perceptual Processes
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Prof. Greg Francis
Good continuation

Object have boundaries

Generally the boundaries run smoothly
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Good continuation

Object have boundaries

Generally the boundaries run smoothly
Purdue University
PSY 310: Sensory and Perceptual Processes
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Prof. Greg Francis
Good continuation

Object have boundaries

Generally the boundaries run smoothly
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Common fate

Motion in a common direction is one example

Can be more complicated than just direction

Biomot.mov
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PSY 310: Sensory and Perceptual Processes
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Prof. Greg Francis
Pragnanz

“Good figure”

Law of simplicity
 The percept you see should be the simplest
interpretation of the scene
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Gestalt Laws



They are not really laws, but suggestions about
what the visual system might be doing
Most people do not really believe them in the
same way we believe the laws of physics or the
law of natural selection
In fact, it is fairly easy to show that the Gestalt
laws are not anywhere near a complete
description of perceptual organization
Purdue University
PSY 310: Sensory and Perceptual Processes
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Prof. Greg Francis
Impossible figures

What is the percept of this image?

Is this “good figure”?
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Impossible figures


This is a
photograph of
a real object
Do you see it
in the
“simplest” way
possible?
Purdue University
PSY 310: Sensory and Perceptual Processes
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Prof. Greg Francis
Impossible figures


This is a
photograph of a
real object
Do you see it in
the “simplest”
way possible?
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Conclusions

Structural psychology

Gestalt psychology

Rules of perceptual organization

Impossible figures
Purdue University
PSY 310: Sensory and Perceptual Processes
13
Prof. Greg Francis
Next time

Perceiving objects

Figure-ground relationships
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PSY 310: Sensory and Perceptual Processes
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