Perceiving &
Recognizing
Objects (Chapter 5)
Wilhelm Wundt (1879):
Our PERCEPTION is
constructed from the
combinations of our
SENSATIONS
Copyright © 2002 Wadsworth Group. Wadsworth is an imprint of the
Wadsworth Group, a division of Thomson Learning
What is this object?
Can you “reverse frame?”
1. Cube floating over
dark circles?
• Cube seen through
(or behind) holes or
perforations?
Gestalt Psychology
In response to Wilhelm Wundt (1879) who proposed that
“perception” was a function of “sensation”
Gestalt psychologists were struck by the many ways in which our
perceptions transcend the simple sensations from which they are
built… and the importance of the “organization of perception”
"The whole is different/greater than the sum of the parts"
How do we “organize” (i.e., cluster, group, give meaning, prioritize)
our sensations into perception?
How do we “organize” (i.e., cluster, group, give meaning, prioritize)
our sensations into perception?
Gestalt Psychology - Perceptual Organization
"The whole is different than the sum of the parts"
Six Gestalt Laws of Perceptual Organization
1. “Pragnanz” – the law of “good figure,” “law of
closure” or “law of simplicity”
“Every stimulus pattern is seen in such a way that the
resulting structure is as simple as possible”
Related to the scientific concept of “parsimony:” In
selecting a criterion for deciding among scientific
theories or explanations, one should always choose
the simplest explanation of a phenomenon, the one
that requires the fewest leaps of logic.
Gestalt Laws
Pragnanz - good figure or simplicity
Gestalt Laws
Pragnanz - good figure or simplicity
Gestalt Laws
Pragnanz - good figure or simplicity
Good fit, closure, simplicity
Six Gestalt Laws of Perceptual Organization
2. Law of Similarity
“Similar things appear to be grouped together”
Circles and squares are
evenly spaced both
horizontally and
vertically, yet we “see”
vertical columns. Why?
Because we group
things that are similar.
Law of Similarity
Six Gestalt Laws of Perceptual Organization
3. Law of good continuation –
“Points that, when connected, result in straight or
smoothly curving lines are seen in such a way as to
follow the smoothest path.”
“Perceptual path of least resistance”
What defines these lines?
a  c? or a  b?
c  b? or c d?
Determined by smoothness
Six Gestalt Laws of Perceptual Organization
4. Law of proximity (or nearness) –
“Things that are near to each other appear to be
grouped together”
This guy doesn’t “belong”
Law of Proximity
Proximity defines propinquity (kinship)
Six Gestalt Laws of Perceptual Organization
5. Law of Common Fate
“Things that are moving in the same direction appear to
be grouped together” – choreography of movement
Six Gestalt Laws of Perceptual Organization
6. Law of familiarity (or meaningfulness) – “Things are
more likely to form groups if the groups appear familiar or
meaningful”
Meaningfulness (Familiarity)
Six Gestalt Laws of Perceptual Organization
6. Law of familiarity (or meaningfulness) – “Things
are more likely to form groups if the groups appear
familiar or meaningful” What do you see below?
Six Gestalt Laws of Perceptual Organization
6. Law of familiarity (or meaningfulness) – “Things
are more likely to form groups if the groups appear
familiar or meaningful” Find the hidden faces below
Six Gestalt Laws of Perceptual Organization
6. Law of familiarity (or meaningfulness) – “Things are
more likely to form groups if the groups appear familiar
or meaningful”
There are allegedly 12 faces
Elaborations of the “laws:” Palmer and Rock
• Principle of common region
• Principle of element connectedness
• Principle of synchrony
Elaborations of the “laws:” Palmer and Rock
• Principle of common region
• Principle of element connectedness
• Principle of synchrony
Elaborations of the “laws:” Palmer and Rock
• Principle of common region
• Principle of element connectedness
• Principle of synchrony
Elaborations of the “laws:” Palmer and Rock
• Principle of common region
• Principle of element connectedness
• Principle of synchrony
Elaborations of the “laws:” Palmer and Rock
• Principle of common region
• Principle of element connectedness
• Principle of synchrony
Gestalt Principles are “Heuristics:” the difference
between algorithms and principles (i.e., best guess, ruleof-thumb, source of hypothesis testing)
Likelihood principle - von Helmholtz
-we will perceive an object that is most likely
the cause of our sensory stimulation
(hypothesis testing)
How do we perceive objects in our world?
Summary of Gestalt rules
1.
2.
3.
4.
5.
6.
Good fit, closure, simplicity
Classical Gestalt
Similarity
“laws”
Good continuity
Proximity
Common fate
Familiarity (meaningfulness)
7. Common region
8. Connectedness
9. Synchrony
Modern Gestalt
“laws”
Remember, How do we perceive objects is dependent on
how we separate (segment, segregate) objects
Fundamental Gestalt question: How do we
separate (segment, segregate) objects
• Understanding “Figure-Ground”
• Are there properties of figure and ground?
Figure-Ground segregation
The figure is more “thing-like” than the ground
Figure-Ground segregation
What is this?
Figure-Ground segregation
1. “Figure” is perceived
as being “in front” of
the ground
2. “Ground” tends to be
perceived in the
surrounding pattern
3. “Figure” is perceived
as the smaller object
4. “Surroundedness”
Figure -Ground Segregation
Small things generally are seen as figure
Figure against the ground
Figure-Ground segregation
The ground is seen as unformed material and seems
to extend behind the figure…
The contour (i.e., lines/edges/endings) separating the
figure from the ground appears to belong to the figure.
Figure -Ground Segregation
Symmetrical areas tend to be seen as figure
Figure -Ground Segregation
Symmetry (i.e., both sides convex or concave) generally
is seen as figure
Symmetry is indicated in “parallelism”
Figure -Ground Segregation
Meaningful things generally are seen as figure
Figure -Ground Segregation
Meaningful things generally are seen as figure
Properties of Figure and Ground?
1.
“Thing-like” appearance
2.
Figure is perceived as “in front” of ground
3.
Ground is perceived by a surrounding stimulus (“surroundedness”)
4.
Figure is perceived as the smaller object
5.
Ground is unformed
6.
Contour “belongs” to the figure
7.
Figure is seen in the symmetry of forms (opposite-mirror images or
parallel images “belong” together)
8.
Meaningfulness of information can infer figure-ground
Alternative models (alternative “levels of analysis”)
to how we “construct” objects in perception
David Marr (1982) Vision
“Computational Approach” to object perception
Individual
Groups of
Features
Features
Retina, LGN,
Cortical Hypercolumns analyses
Objects
Extrastriate Cortical
regions
(Inferotemporal lobe,
V4 (color), etc.)
Scenes
Extrastriatal
“cross-talk” &
synchrony (IT,
MT, Parietal
lobe, feedback to
LGN, etc.)
Object Perception in Stages
Anne Treisman's "feature integration theory" (FIT)
Preattentive
Stage
identify
Primitives
(line/edge)
preattentive
"automatic"
processing
Focused Attention
Stage
attentional
devise
-focus on
some
features
Chapter 6: Attention
and Experiencing a
Coherent World
Pages 142-145
combine
features
or primitives
Perception
of three
dimensional
world
Compare to
memory
Identify Object
Object Perception in Stages
Treisman's "feature integration theory" (FIT)
identify
primitives
preattentive
"automatic"
processing
Preattentive Stage:
Visual system (retina, LGN,
Hypercolumns) analyzes features
such as curvature, orientation, length,
color, movement, etc.
“Non-conscious processes”
Preattentive Stage: Identify and analyze
“primitives” (i.e., features)
How do we see features? Method 1 “pop-out” boundaries
Example of when pop-out occurs: when there are
texturally different fields
Example of when pop-out occurs: when
there are different texture fields
Items that POP OUT are visual primitives
- line orientation, curvature, color,
depth, line ends, motion etc.
O
O
O
O
O
O O O
O
O
O
Why doesn't the red vertical bar POP OUT?
Because it requires attention and analysis
Object Perception in Stages
Treisman's "feature integration theory" (FIT)
identify
primitives
preattentive
"automatic"
processing
Focused attention:
attentional
devise
-focus on
some
features
Narrows the range
of what an
individual attends to
in the wider visual
array
Object Perception in Stages
Treisman's "feature integration theory" (FIT)
identify
primitives
preattentive
"automatic"
processing
Focused attention:
attentional
devise
-focus on
some
features
combine
features
or primitives
Narrows the range
of what an
individual attends to
in the wider visual
array
With narrowed
attention, features
are combined and
object is perceived
Object Perception in Stages
Treisman's "feature integration theory" (FIT)
identify
primitives
preattentive
"automatic"
processing
attentional
devise
-focus on
some
features
combine
features
or primitives
Perception
of three
dimensional
world
Compare to
memory
Identify Object
Focused Attention Stage: What if the
stimulus doesn’t just “pop-out?”
How do we see features? Method 2 visual search and
“back-end” processing of Feature Integration Theory
Need for combining & perceiving objects & using
cognitive processes (i.e., comparing to memory)
Focused Attention Stage: What if the
stimulus doesn’t just “pop-out?”
How do we see features? Method 2 visual search and
“back-end” processing of Feature Integration Theory
Combining & perceiving (c) requires both Ventral
(“what is it?”) and Dorsal (“where is it?”) pathways
and cross-talk of both
Example of when pop-out does NOT occur:
when comparison to memory is involved
Pop-Out in Visual Search - Anne Treisman
2 distractors
V
O
V
T
5 distractors
T
V
L
O
V V
V
V
T T
T
L T T
10 distractors
V V
V
O
V
V
V V V
V
V
T T
T
T
LT T
T
T T T
Reaction Time
To find a red vertical bar amongst
green vertical bars
2
5
10
Reaction Time
# of distractors
To find an "L" amongst "T"s
2
5
10
# of distractors
Anne Treisman’s conclusions about Basic Features
• Pop-out occurs with stimuli such as:
–
–
–
–
–
–
Curvature
Orientation
Line ends/lengths
Movement
Brightness
Direction of illumination
• These types of stimuli are processed largely at the
“beginning” of visual processing
– The preattentive stage
– Not yet at the stage to “form objects” per se
– Probably processed by the Retina, LGN & Striate cortex (V1)
Anne Treisman’s conclusions about “non-Basic”
Features
• Stimuli that don’t pop-out require more elaborate
analyses:
–
–
–
–
–
Ventral “what is it” pathway
Dorsal “where/how” pathway
Influenced by attentional factors
Influenced by motivational and circumstantial factors
Reliant on higher memory
• These types of stimuli are processed largely at the “end” of
visual processing:
–
–
–
–
Attentional factors involve several brain areas
At the stage of “formed objects” from combining features
Probably processed largely by the Extrastriatal areas
Cross-talk among several higher brain areas
Biederman's Recognition-by-Components (RBC)
1
3
2
4
“geons” – limited set
of elements of
geometric shapes
3
5
5
Biederman's Recognition-by-Components (RBC)
Biederman's Recognition-by-Components (RBC)
Cells in the Inferotemporal Lobe differentially
respond to different geometric shapes
If you can see most of the geons, you can
identify the object.
How do we parse our perceptual world?
• Neurological
– Dorsal (“where”) pathway
– Ventral (“what”) pathway
• Gestalt grouping rules
– Segregate, separate
– Figure-Ground
• Experience & knowledge
–
–
–
–
–
Faces
Geons
Viewpoint Effect
How we pay attention
Modifications of the Neurology
You can read this upside down!
VIEWPOINT EFFECT & VIEWPOINT
CONSTANCY
• Viewpoint effects: ability to perceive an object from a
different perspective (i.e., rotated or turned version from
the original object).
• Each image perceived activates a different set of receptors
on the retina;
– however, we perceive the different images as representing the
same object.
View-Based Theories
(Template theories)
• we mentally rotate the image until it matches a similar
representation already in our memory
• the representations in our memory that we already have are
simple (and/or abstract, i.e., what do you think of when you
think “dog”)
• should take longer for the perceiver to recognize the same
object the more that it is rotated from its normal and most
common representation.
• VIEWPOINT DEPENDENT
Notice anything different about these two pictures?
It’s the same person, with one small difference.
One image has been altered, but most people won’t see how until
they’re viewed upright.
Thank you Jon D.
• This is one example of the “inversion effect”
– it’s harder for the brain to process upside-down objects
than upright objects
– Effect is particularly strong for the perception of faces
How do we “organize” (i.e., cluster, group, give
meaning, prioritize) our sensations into perception?
1. Partly by non-conscious analysis of features
2. Partly by conscious analysis of features
3. Partly by what drives attention & memory
4. Partly by what we “know” about what we are perceiving
How we direct attention:
Stimulus Salience
How we direct attention:
Stimulus Salience
Attentional
Capture:
Analogous to
Treisman’s
“preattentive”
stage:
Lights,
movements,
sounds, contours,
etc.
How we direct attention:
Cognitive Factors
Active cognitive processes drive our attention
How we direct attention:
Cognitive Factors
Active cognitive
processes drive our
attention
How we direct attention:
Cognitive Factors
Active cognitive processes drive our attention: where is Justin
Beiber?
How we direct attention:
Cognitive Factors
Active cognitive processes drive our attention: where is Justin
Beiber?
And: Miley Cyrus
Or Rihanna?
• Attention –
– a concept of how we actively process information
present in our environment
• Think of attention as a highlighter –
– As we read through a book, the highlighted section
draws us in, causing us to focus on that area
– Attention allows us to “tune-out” information, sensations
and perceptions that are not relevant at the moment, and
instead focus on “important” information.
“Spotlight” of Attention
• Overt Attention: directing a sense
organ at a stimulus.
– Reading the words on this slide
• Covert Attention: processing
information outside of your direct
focus.
– Pointing your eyes toward this slide
while watching someone in your
peripheral vision
How do we parse our perceptual world?
• Neurological
– Dorsal (“where”) pathway
– Ventral (“what”) pathway
• Gestalt grouping rules
– Segregate, separate
– Figure-Ground
• Experience & knowledge
–
–
–
–
–
Faces
Geons
Viewpoint Effect
How we pay attention
Modifications of the Neurology
The “knowledge” problem
• Perception is more than just interpreting sensation
• How far have we come in the last 100+ years?
– Not very far (Gestalt “laws” still hold up)
– Exception is in the understanding of the
neurophysiology
• What’s missing: understanding the interplay
between “attention,” “knowledge” and
“perception”