Gestalt Principles of Perception
Psychology 355: Cognitive Psychology
Instructor: John Miyamoto
04/08/2015: Lecture 02-3
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Outline
• Gestalt Principles of Perception
• Lateral inhibition & feature representations in perception
• Phenomenological evidence for motion detectors in vision
Psych 355, Miyamoto, Spr '15
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Slide repeated from yesterday
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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Gestalt Principle of Similarity
Slide repeated from yesterday
• Similar things are grouped together.
• Similarity in lightness, shape, color,
size, and orientation cause grouping.
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Psych 355, Miyamoto, Spr '15
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Principle of Good Continuation
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Slide repeated
from yesterday
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.
Slide repeated from yesterday
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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Slide repeated from yesterday
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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Slide repeated from yesterday
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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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
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Psych 355, Miyamoto, Spr '15
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Goldstein Figure 3.21: Gestalt Principles Can Trick the Eye
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
Same Slide - No Arrows or Extra Lines
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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
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 Good Continuation:
We "see" the motion of the leaf.
Principle of Simplicity
Summary: Evidence for Gestalt Principle of Perception
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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
Examples of Visual Feature Detectors
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Examples of Visual Feature Detectors
• Hubel & Wiesel used single-cell recordings to demonstrate the
existence of feature detectors in the visual system.
• Lots of evidence for feature detectors:
♦
Single-cell recordings
♦
Visual illusions that can be explained by lateral inhibition (inhibition of
neighboring neurons)
♦
fMRI evidence (not discussed in this lecture)
• Many different types of neural feature detectors have been found:
edge and bar detectors, motion detectors, texture detectors, color
detectors, etc.
• Important Hypothesis: Many perceptual and cognitive processes are
based on feature representations.
Psych 355, Section, Spr '15
Lateral Inhibition
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Lateral Inhibition
• Cells that are ON-center/OFF surround
inhibit activity of adjacent cells when
the center is stimulated.
• Lateral inhibition refers to the effects of
inhibition on adjacent neurons,
especially when the inhibition enhances
the perception of edges, bars or other
patterns.
Psych 355, Section, Spr '15
Lateral Inhibition Plays a Role in Edge & Bar Detectors
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Hermann Grid
Stare at the grid.
What do you see?
Psych 355, Miyamoto, Spr '15
Apply Idea of Lateral Inhibition to Construction of Edge & Bar Detectors
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Two Perceptual Phenomena with the Hermann Grid
1) Phantom dark
spots appear at
the intersections
of the white
lines.
2) The dark spots
disappear when
you look directly
at them.
Why?
Psych 355, Miyamoto, Spr '15
Use Lateral Inhibition to Explain the Perception of the Hermann Grid
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Hermann Grid Illusion is Due to Lateral Inhibition?
We see phantom dark spots at the intersections to the side of
the focus of vision because .....
There is
more
lateral
inhibition
at the
intersection
than in the
middle of a
white bar.
Psych 355, Miyamoto, Spr '15
Receptive
fields are
smaller in the
fovea (center
of vision)
than away
from the
fovea.
Lateral Inhibition & Edge Detectors
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Edge Detectors and Bar Detectors in Visual Cortex
• Lateral inhibition helps
neurons to work together to
create edge and bar detectors.
• Lateral inhibition enhances the
perception of edges.
Anderson, Figure 2.07
Anderson, Figure 2.09
Psych 355, Miyamoto, Spr '15
More Evidence for Feature Detectors – Motion Aftereffects
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Evidence for Motion Detectors – Motion Aftereffects
• Waterfall Illusion (this is one of the original discoveries
that lead to the study of motion aftereffects)
http://www.georgemather.com/MotionMP4.html
Click on the "Waterfall Illusion"
• Expanding Buddha: http://www.michaelbach.de/ot/mot-adapt/index.html
♦
Set the display to "Full Screen". Choose whether you want the Buddha to
expand or contract. Then click "start."
• Motion aftereffects give evidence for motion detectors in the visual
system.
♦
Persistent activation of a motion detector reduces its sensitivity (adaptation).
When the motion is stopped, we “see” motion
in the opposite direction.
♦
These motion aftereffects support the general claim that there are
feature detectors in the visual system.
Psych 355, Miyamoto, Spr '15
Summary: Visual Feature Detectors
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Summary - Visual Feature Detectors
• Hubel & Wiesel used single-cell recordings to demonstrate the
existence of feature detectors in the visual system.
• Lots of evidence for feature detectors:
♦
Single-cell recordings
♦
Visual illusions that can be explained by lateral inhibition (inhibition of
neighboring neurons)
♦
fMRI evidence (not discussed in this lecture)
• Many different types of neural feature detectors have been found:
edge and bar detectors, motion detectors, texture detectors, color
detectors, etc.
• Important Hypothesis: Many perceptual and cognitive processes are
based on feature representations.
Psych 355, Miyamoto, Spr '15
END
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