Perceptual Heuristics
& Gestalt Principles of Perception
Psychology 355: Cognitive Psychology
Instructor: John Miyamoto
04/07/2015: Lecture 02-2
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The Cognitive Side of Perception
• Unconscious inference is pervasive in perception
• Bottom Up & Top Down Processing
• Inverse Projection Problem
• Perceptual heuristics
• Gestalt Principles of Perception: Some examples
♦
Preliminary topic to object perception
Psych 355, Miyamoto, Spr '15
Bottom Up & Top Down Processing
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Bottom Up and Top Down Processing
• Bottom up processing – processing of current stimulation influences
what is perceived
• Top down processing – person’s background knowledge, learning and
expectations influence what is perceived.
Bottom up processing is data driven.
Top down processing is theory-driven,
knowledge-driven, and context-driven.
Example of top down processing:
Your knowledge of rectilinear solids
informs your perception.
Psych 355, Miyamoto, Spr '15
Examples of Top Down and Bottom Up Processing
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Examples of Bottom Up Processes
• Elementary feature detection, e.g., edge detectors, bar detectors,
motion detectors.
• The following color perception is bottom up:

Your perception of the red squares is dictated by the stimulus;
the perception is not influenced by prior expectations or beliefs.
• Similarly, the perceived motion
of the blue disk is bottom up.
It is controlled by the stimulus,
not by your beliefs or expectations.
Psych 355, Miyamoto, Spr '15
Example of Top Down Processing
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Examples of Top Down Processes
• When people see a plane crash, at least some witnesses
always claim to have seen flames coming from the engines.
♦
(Top-down when claim is false; either top-down or bottom up when
it is true.)
• Scene understanding involves both top-down and bottom-up
processing.
Psych 355, Miyamoto, Spr '15
Classroom Experiment
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Class Experiment: Demonstration of Top Down Processing
• Instructor:
Divide the classroom into a “left group” and “right group”.
• I will show you an image.
Briefly write down a label for what you see.
E.g., if you see a chair, write down “chair.”
• Left half of the room will close their eyes for the first image.
Right half of the room will close their eyes for the second image.
• Everyone will open their eyes and complete the experiment.
Psych 355, Miyamoto, Spr '15
Image 1a
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Students on Left – Eyes Open
Students on Right – Eyes Closed
Label this image “Image 1a”.
Write down a name for what you see.
Psych 355, Miyamoto, Spr '15
Image 1b
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Students on Left – Eyes Closed
Students on Right – Eyes Open
Label this image “Image 1b”.
Write down a name for what you see.
Psych 355, Miyamoto, Spr '15
Image 2
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Everybody’s Eyes Open
Label this image “Image 2”.
Write down a name for what you see.
Psych 355, Miyamoto, Spr '15
Collect Results of Class Demo Experiment
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Results of Classroom Experiment
• We will only collect data for what you saw in Image 2.
• People on the LEFT SIDE:
Raise your right arm if you wrote down
“mouse” or “rat” for Image 2?
Raise your left arm if you wrote down
“old man” or “man” or “face” for Image 2?
• People on the RIGHT SIDE:
Raise your right arm if you wrote down
“mouse” or “rat” for Image 2?
Raise your left arm if you wrote down
“old man” or “man” or “face” for Image 2?
Psych 355, Miyamoto, Spr '15
Show Images 1a, 1b, 2
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LEFT SIDE saw Image 1a
EVERYONE saw
Image 2
RIGHT SIDE saw Image 1b
Top Down Processing:
What you see in
Image 2 depends in part
on what you expect
from Image 1.
.
Psych 355, Miyamoto, Spr '15
Summary re Bottom Up & Top Down Processing
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Summary re Bottom Up & Top Down Processing
• What we see is usually the consequence of both top-down and
bottom-up processing.
• Remember Helmholtz’s unconscious inference.
Top down processes (inferences) fill in information
that is not present in the actual stimulus.
Psych 355, Miyamoto, Spr '15
Inverse Projection Problem
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Inverse Projection Problem
Inverse Project Problem: For any 2-dimensional image that is projected
onto the retina, there are infinitely many different 3-dimensional shapes that
could have produced that image.
How does the mind decide which shape actually produced the
2-dimensional projected image?
Psych 355, Miyamoto, Spr '15
Ambiguous Figures: The Ambiguous Box
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Example: Ambiguous Images
• Do you experience competing interpretations of the image?
(I.e., do you experience "Gestalt shifts in perception")
Box viewed from above,
versus
Box viewed from below
Psych 355, Miyamoto, Spr '15
Young/Old Woman
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Example: Ambiguous Images
• Do you experience competing
interpretations of the image?
(a.k.a. "Gestalt shifts in perception")
Young woman
mouth
versus
mouth
Old woman
Same Image Without the “Mouth” Labels
Psych 355, Miyamoto, Spr '15
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Example: Ambiguous Images
• Do you experience
competing interpretations
of the image? (a.k.a.
"Gestalt shifts in
perception")
Young woman,
versus
Old woman
Inverse Problem – How Does the Visual System Decide What is 3-D Object?
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How Does the Visual System Answer the Question:
What Is the Real Object
That Produces the Stimulation at the Retina?
Basic answers:
• The visual system makes a variety of unconscious inferences
(Helmoltz's idea).
• The visual system uses cues for object relations that usually work
(but the system can be fooled by a clever stimulus).
Psych 355, Miyamoto, Spr '15
What Is a Heuristic?
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What is a Heuristic?
• A heuristic is a reasoning strategy that is used to solve a problem,
make a decision or form a judgment about something.
• Perceptual heuristic: A strategy in perceptual information
processing that (typically) helps to determine the objective situation
that produced the immediate sensations.
• Heuristics are typically useful shortcuts.
• Heuristics are often adaptive, but they can lead to systematic errors.
Psych 355, Miyamoto, Spr '15
Craters versus Mounds
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Example: Craters or Mounds?
Typically Craters
Typically Mounds
“Light comes from above” assumption guides perception.
Psych 355, Miyamoto, Spr '15
Repeat this Slide with Ellipses that Pick Out Corresponding Craters and Bumps
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Example: Craters or Mounds?
Typically Craters
Typically Mounds
“Light comes from above” assumption guides perception.
Psych 355, Miyamoto, Spr '15
Why Idea of Unconscious Inference Is Important for Cog Psych
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2-D Artwork That Looks Like 3-D (Sketch)
Downloaded from: http://www.dailydot.com/entertainment/lego-chalk-army/
Work is attributed to: http://www.planetstreetpainting.com/
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2-D Artwork That Looks Like 3-D (Finished Product)
Downloaded from: http://www.planetstreetpainting.com/
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The Ames Room
• Look at
http://www.yorku.ca/eye/Ames%20room.htm
• Another example:
http://presurfer.blogspot.com/2007_0
5_01_archive.html
Psych 355, Miyamoto, Spr '15
Video of the Ames Room
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A Video Example of the Ames Room
Errol & Ricky: http://www.youtube.com/watch?v=5ic7QGjGEX8
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Where We Are Headed in the Perception Topic
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Where We Are Headed in the Perception Topic
• The point made by the previous slides:
Our perceptual system solves the inverse projection problem
by applying various perceptual heuristics.
♦
Perceptual heuristics are strategies that provide “best guesses” about
the stimulus object.
• Next: Gestalt Principles of Perception
Psych 355, Miyamoto, Spr '15
Gestalt Principles of Perception
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Inverse Projection Problem
Inverse Project Problem: For any 2-dimensional image that is projected
onto the retina, there are infinitely many different 3-dimensional shapes that
could have produced that image.
How does the mind decide which shape actually produced the
2-dimensional projected image?
Psych 355, Miyamoto, Spr '15
Ambiguous Figures: The Ambiguous Box
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The Gestalt Approach
• Emerged in early 20th century in response to structuralism.
(Structuralism claimed that perception was bottom up –
it was built up from simple, atomistic sensations.)
• Basic question of the Gestalt approach to perception:
What principles govern the grouping of the components of a
perceptual stimulus into an object or organized group of objects?
• Gestalt principles are sometimes called heuristics—these provide
“best guesses” about the stimulus object.
Psych 355, Miyamoto, Spr '15
Principle of Similarity
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Gestalt Principle of Similarity
• Similar things are grouped together.
• Similarity in lightness, shape, color,
size, and orientation cause grouping.
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Principle of Good Continuation
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Gestalt Principle of Good Continuation
• Connected points result in smoothly curving lines.
• Points are seen as they belong together.
• Lines follows smooth path.
Psych 355, Miyamoto, Spr '15
Figure-Ground Principle
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Figure-Ground Principle and the Principle of Smallness
Face is
background
• Figure/ground Principle –
ambiguous figure
The famous faces/vase figure.
Psych 355, Miyamoto, Spr '15
Face is
foreground
Principle of Smallness implies
that we should see vases on the
left and faces on the right
Escher Print #1
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Figure-Ground Example
• Downloaded from
http://www.worldofescher.com/gall
ery/A41L.html
• Maurits Cornelis Escher
Dutch graphics artist
1898 - 1972
• Figure-ground problem:
Separation of object
from background
Psych 355, Miyamoto, Spr '15
Escher Print #2
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Another Figure-Ground Example
• Downloaded from http://www.worldofescher.com/gallery/A11L.html
Psych 355, Miyamoto, Spr '15
Principle of Common Fate
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Tuesday, April 07, 2015: The Lecture Ended Here
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Gestalt Principle: Common Fate
• Principle of common fate: Things that are moving in the same
direction (at the same speed) appear to be grouped together.
• Go to website – look at it:
• http://tepserver.ucsd.edu/~jlevin/gp/time-example-common-fate/
This is a nice demonstration of the common fate principle. The
groups of lines or shapes are only visible as a group when they are
moving together.
♦
WARNING: The preceding demonstration requires a browser that has JAVA
activated. I don’t understand the technicalities, but there are
dangers (computer viruses) associated with the use of JAVA.
• If preceding example is not available,
try http://www.georgemather.com/MotionDemos/KDEQT.html: Kinetic depth effect
P 355, Miyamoto, Winter '09
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Examples of Gestalt Principle in Visual Design
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Examples of Gestalt Principles in the World of Visual Design
Principle of similarity implies that we
see the three left figures as a group.
Thus the right figure is an exception
(anomaly) so it stands out.
Principle of Figure/Ground
Psych 355, Miyamoto, Spr '15
Principle of continuation: We
"see" the motion of the leaf.
Principle of Simplicity
Summary: Evidence for Gestalt Principle of Perception - END
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Goldstein Figure 3.21
What Gestalt principles are used here to
create the illusion of a semi-transparent
woman?
• Principle of Good Continuation
• Principle of Similarity
Figure 3.21 Waves by Wilma Hurskainen
Psych 355, Miyamoto, Spr '15
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Goldstein Figure 3.21
What Gestalt principles are used here to
create the illusion of a semi-transparent
woman?
• Principle of Good Continuation
• Principle of Similarity
Figure 3.21 Waves by Wilma Hurskainen
Psych 355, Miyamoto, Spr '15
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Summary – Evidence for Gestalt Principles of Perception
• Phenomenological support
• Experimental evidence – image segmentation
(Not discussed in this lecture)
• Gestalt laws are perceptual heuristics
• Gestalt laws help to explain how the visual system solves
the inverse projection problem (inferring a specific reality from ambiguous inputs).
• Important in the theory of object perception
Psych 355, Miyamoto, Spr '15
END
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