1. Perceptual Heuristics & Gestalt Principles of Perception
Psychology 355: Cognitive Psychology Instructor: John Miyamoto 04/07/2015: Lecture 02-2
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2. 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
Bottom Up & Top Down Processing
Psych 355, Miyamoto, Spr '15

3. 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.
Examples of Top Down and Bottom Up Processing
Psych 355, Miyamoto, Spr '15

4. 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.
Example of Top Down Processing
Psych 355, Miyamoto, Spr '15

5. 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.
Classroom Experiment
Psych 355, Miyamoto, Spr '15

6. 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.
Image 1a
Psych 355, Miyamoto, Spr '15

7. Students on Left – Eyes Open Students on Right – Eyes Closed
Label this image “Image 1a”. Write down a name for what you see.
Image 1b
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8. Students on Left – Eyes Closed Students on Right – Eyes Open
Label this image “Image 1b”. Write down a name for what you see.
Image 2
Psych 355, Miyamoto, Spr '15

9. Label this image “Image 2”. Write down a name for what you see.
Everybody’s Eyes Open
Label this image “Image 2”. Write down a name for what you see.
Collect Results of Class Demo Experiment
Psych 355, Miyamoto, Spr '15

10. 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:
Show Images 1a, 1b, 2
Psych 355, Miyamoto, Spr '15

11. . LEFT SIDE saw Image 1a RIGHT SIDE saw Image 1b
Top Down Processing: What you see in Image 2 depends in part on what you expect from Image 1.
EVERYONE saw Image 2 .
Summary re Bottom Up & Top Down Processing
Psych 355, Miyamoto, Spr '15

12. 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.
Inverse Projection Problem
Psych 355, Miyamoto, Spr '15

13. Inverse Projection Problem
Object could be created by the larger more distant rectangle or the tilted trapezoid.
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? 13
Ambiguous Figures: The Ambiguous Box
Psych 355, Miyamoto, Spr '15

14. 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 14
Young/Old Woman
Psych 355, Miyamoto, Spr '15

15. Example: Ambiguous Images
Do you experience competing interpretations of the image? (a.k.a. "Gestalt shifts in perception")
Young woman
versus
Old woman
mouth
mouth 15
Same Image Without the “Mouth” Labels
Psych 355, Miyamoto, Spr '15

16. Example: Ambiguous Images
Do you experience competing interpretations of the image? (a.k.a. "Gestalt shifts in perception")
Young woman,
versus
Old woman 16
Inverse Problem – How Does the Visual System Decide What is 3-D Object?
Psych 355, Miyamoto, Spr '15

17. 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).
What Is a Heuristic?
Psych 355, Miyamoto, Spr '15

18. 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.
Craters versus Mounds
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19. Example: Craters or Mounds?
Typically Craters Typically Mounds
“Light comes from above” assumption guides perception.
Repeat this Slide with Ellipses that Pick Out Corresponding Craters and Bumps
Psych 355, Miyamoto, Spr '15

20. Example: Craters or Mounds?
Typically Craters Typically Mounds
“Light comes from above” assumption guides perception.
Why Idea of Unconscious Inference Is Important for Cog Psych
Psych 355, Miyamoto, Spr '15

21. 2-D Artwork That Looks Like 3-D (Sketch)
Downloaded from: Work is attributed to:
* See ‘E:\p355\IMAGES\2d.like.3d.ini.planetstreetpainting.jpg’ for the image.
Psych 355, Miyamoto, Spr '15

22. 2-D Artwork That Looks Like 3-D (Finished Product)
Downloaded from:
* See ‘E:\p355\IMAGES\2d.like.3d.planetstreetpainting-4.jpg’ for the image.
Psych 355, Miyamoto, Spr '15

23. The Ames Room Look at http://www.yorku.ca/eye/Ames%20room.htm
Another example:
Video of the Ames Room
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24. A Video Example of the Ames Room
Errol & Ricky:
Where We Are Headed in the Perception Topic
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25. 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
Gestalt Principles of Perception
Psych 355, Miyamoto, Spr '15

26. Inverse Projection Problem
Object could be created by the larger more distant rectangle or the tilted trapezoid.
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? 26
Ambiguous Figures: The Ambiguous Box
Psych 355, Miyamoto, Spr '15

27. 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.
A heuristic is a “rule of thumb” that provides a best-guess solution to a problem. Gestalt laws do not always result in accurate perceptions of the environment. Contrast with algorithm, which is a procedure that is guaranteed to solve a problem. 27
Principle of Similarity
Psych 355, Miyamoto, Spr '15

28. Gestalt Principle of Similarity
Similar things are grouped together.
Similarity in lightness, shape, color, size, and orientation cause grouping.
a a a a a a a a b c d e f g b b b b b b b a b c d e f g c c c c c c c a b c d e f g d d d d d d d a b c d e f g e e e e e e e a b c d e f g f f f f f f f a b c d e f g g g g g g g g a b c d e f g
(looks like rows) (looks like columns)
Principle of Good Continuation
Psych 355, Miyamoto, Spr '15

29. Gestalt Principle of Good Continuation
Connected points result in smoothly curving lines.
Points are seen as they belong together.
Lines follows smooth path.
Figure-Ground Principle
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30. Figure-Ground Principle and the Principle of Smallness
Face is Face is background foreground
Figure/ground Principle – ambiguous figure The famous faces/vase figure.
Principle of Smallness implies that we should see vases on the left and faces on the right
Escher Print #1
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31. Figure-Ground Example
Downloaded from ery/A41L.html
Maurits Cornelis Escher Dutch graphics artist
Figure-ground problem: Separation of object from background
Escher Print #2
Psych 355, Miyamoto, Spr '15

32. Another Figure-Ground Example
Downloaded from
Principle of Common Fate
Psych 355, Miyamoto, Spr '15

33. Tuesday, April 07, 2015: The Lecture Ended Here
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34. 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:
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 Kinetic depth effect 34
P 355, Miyamoto, Winter '09 34
Examples of Gestalt Principle in Visual Design
Psych 355, Miyamoto, Spr '15

35. 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 continuation: We "see" the motion of the leaf.
Principle of Figure/Ground
Principle of Simplicity
Psych 355, Miyamoto, Spr '15
Summary: Evidence for Gestalt Principle of Perception - END

36. 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 Waves by Wilma Hurskainen
Psych 355, Miyamoto, Spr '15

37. 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 Waves by Wilma Hurskainen
Psych 355, Miyamoto, Spr '15

38. 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
END
Psych 355, Miyamoto, Spr '15