Chapter 4: Perception

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Transcript Chapter 4: Perception

Cognition, Sixth Edition, Robert J. Sternberg
Chapter 2
Perception
Cognition, Sixth Edition, Robert J. Sternberg
What you want to remember
• Perception is more than photons
and pressure.
• Perception is divided from
cognition/emotion but they are
often intertwined.
• Perception follows laws and
heuristics.
Chapter 2
Cognition, Sixth Edition, Robert J. Sternberg
Chapter 2
Sensation
• Sensation - the registration of
physical stimuli
– Hearing - anatomy and function of the
ear
– Vision - anatomy and function of the eye
Cognition, Sixth Edition, Robert J. Sternberg
Chapter 2
Sensation
• What is the purpose of sensory
processing?
– To transform physical stimuli in the
environment into neural signals in the
brain
– Example (Hearing): Sound waves are
transformed into vibrations in the ear,
and the strength of those vibrations are
coded by sensory neurons
Cognition, Sixth Edition, Robert J. Sternberg
Chapter 2
Some Questions of Interest
• How can we perceive an object like
a chair as having a stable form,
given that the image of the chair on
our retina changes as we look at it
from different directions?
Cognition, Sixth Edition, Robert J. Sternberg
Chapter 2
Some Questions of Interest
• What are two fundamental
approaches to explaining
perception?
• What happens when people with
normal visual sensations cannot
perceive visual stimuli?
Cognition, Sixth Edition, Robert J. Sternberg
Chapter 2
Perception Is…
• The process of recognizing,
organizing, and interpreting
information
• How do you recognize these items?
Cognition, Sixth Edition, Robert J. Sternberg
Chapter 2
Basic Concepts (Gibson)
• Distal object
– Grandma’s face
• Informational medium
– Reflected light from Grandma’s face
• Proximal stimulation
– Photon absorption in the rod and cone
cells of the retina
• Perceptual object
– Grandma’s face
Cognition, Sixth Edition, Robert J. Sternberg
Chapter 2
Perceptual Basics
• Sensory adaptation
– Occurs when sensory receptors
change their sensitivity to the stimulus
– Constant stimulation leads to lower
sensitivity
• Our senses respond to change
• Perceptual training
Cognition, Sixth Edition, Robert J. Sternberg
Chapter 2
Perceptual Illusions
• Sometimes we
cannot perceive
what does exist
• Sometimes we
perceive things
that do not exist
Cognition, Sixth Edition, Robert J. Sternberg
Chapter 2
Perceptual Illusions
• Sometimes we
perceive what
cannot be there
Cognition, Sixth Edition, Robert J. Sternberg
http://www.vimm.it/cochlea/cochleapages/overview/history.htmChapter 2
Cognition, Sixth Edition, Robert J. Sternberg
Chapter 2
Figure 7.4
Figure 7.4 The basilar membrane of the human cochlea. High-frequency
sounds produce their maximum displacement near the base. Low-frequency
sounds produce their maximum displacement near the apex.
Cognition, Sixth Edition, Robert J. Sternberg
Chapter 2
Auditory Cortex
• Tonotopic organization in superior temporal lobe
Corresponds to
apex of cochlea
Primary
auditory
cortex
Secondary
auditory
cortex
Corresponds to
base of cochlea
Cognition, Sixth Edition, Robert J. Sternberg
Typical human range about 20 - 20 kHz
Audiograms for various species
Chapter 2
Cognition, Sixth Edition, Robert J. Sternberg
Chapter 2
Our Visual System
• Light travels through
the eye and focuses
on the retina
– Electromagnetic light
energy is converted
into neural
electrochemical
impulses
Cognition, Sixth Edition, Robert J. Sternberg
Chapter 2
Our Visual System
• Three main layers of
neural tissue in
retina
– Ganglion cells
– Amacrine cells,
horizontal cells,
bipolar cells
– Photoreceptors
• Rods and cones
Cognition, Sixth Edition, Robert J. Sternberg
Chapter 2
Visual Pathways in the Brain
• What/where hypothesis
– One path for identifying
• Temporal lobe lesions in
monkeys
– Can indicate where but not what
– Another for spatially locating
• Parietal lobe lesions in monkeys
– Can indicate what but not where
Cognition, Sixth Edition, Robert J. Sternberg
Chapter 2
Theories of Perception
• Bottom-up theories
– Parts are identified, put together, and
then recognition occurs
• Top-down theories
– People actively construct perceptions
using information based on
expectations
Cognition, Sixth Edition, Robert J. Sternberg
Chapter 2
Bottom-Up Processing Theories
•
•
•
•
Direct perception
Template theories
Feature-matching theories
Recognition-by-components theory
Cognition, Sixth Edition, Robert J. Sternberg
Chapter 2
Template Theories
• Basics of template theories
– Multiple templates are held in memory
– To recognize the incoming stimuli, you
compare to templates in memory until a
match is found
Search memory for a match
See stimuli
Cognition, Sixth Edition, Robert J. Sternberg
Chapter 2
Template Theories
• Weakness of theory
– Problem of imperfect matches
– Cannot account for the flexibility of
pattern recognition system
Search for match in memory
See stimuli
No perfect match in memory
Cognition, Sixth Edition, Robert J. Sternberg
Chapter 2
Feature-Matching Theories
• Recognize objects on the basis of a
small number of characteristics
(features)
– Detect specific elements and assemble
them into more complex forms
– Brain cells that respond to specific
features such as lines and angles are
referred to as “feature detectors”
Cognition, Sixth Edition, Robert J. Sternberg
Chapter 2
Pandemonium Model
• Four kinds of
demons
– Image demons
– Feature demons
– Cognitive demons
– Decision demons
Cognition, Sixth Edition, Robert J. Sternberg
Chapter 2
Physiological Evidence for
Features
• Hubel & Wiesel (1979)
– Simple cells detect bars or
edges of particular orientation
in particular location
– Complex cells detect bars or
edges of particular orientation,
exact location abstracted
– Hypercomplex cells detect
particular colors (simple and
complex cells), bars, or edges
of particular length or moving
in a particular direction
Cognition, Sixth Edition, Robert J. Sternberg
Chapter 2
Recognition-by-Components
(RBC) Theory
• Biederman (1987)
– Describes how 3D
images are identified
– Breaks objects down
into geons
– Objects are identified
by geons, relationship
between them
Cognition, Sixth Edition, Robert J. Sternberg
Chapter 2
Gibson’s Theory of Direct
Perception (Ecological psych)
• The information in our sensory
receptors is all we need to perceive
anything
– Do not need the aid of complex
thought processes to explain
perception
Cognition, Sixth Edition, Robert J. Sternberg
Chapter 2
Gibson’s Theory of Direct
Perception (Ecological psych)
• Use texture gradients as cues for
depth and distance
– Allows us to perceive directly the relative
proximity or distance of objects
Cognition, Sixth Edition, Robert J. Sternberg
Chapter 2
Top-Down Processing
(Constructive Approach)
• Perception is not automatic from raw
stimuli
• Processing is needed to build
perception
• Top-down processing occurs quickly
and involves making inferences,
guessing from experience, and basing
one perception on another
Cognition, Sixth Edition, Robert J. Sternberg
Chapter 2
Evidence for Top-Down
Processing
•Context effects
Context helps us to be able to recognize letters in many different
styles.
Context helps us to be able to recognize letters in many different styles.
Context helps us to be able to recognize letters in many different styles.
Cognition, Sixth Edition, Robert J. Sternberg
Chapter 2
Configural-Superiority Effect
• Objects presented in context are
easier to recognize than objects
presented alone
• Task: Spot the different stimuli,
press button
Cognition, Sixth Edition, Robert J. Sternberg
Chapter 2
Configural-Superiority Effect
Target
Composite
Measure reaction time
Target alone = 1884 Composite = 749
Target spotted faster in a context!
Cognition, Sixth Edition, Robert J. Sternberg
Chapter 2
Which Approach Is Right?
• Top-down or bottom-up
– Perhaps a bit of both
Cognition, Sixth Edition, Robert J. Sternberg
Chapter 2
Beginning of Gestalt psychology
• 1910 – Max Wertheimer on vacation
noticed that distal objects seemed to
move with the train; nearby objects
went past. Why?
• Study of apparent motion – why
stationary objects appear to move
Cognition, Sixth Edition, Robert J. Sternberg
Chapter 2
Apparent motion
• Phi phenomenon – flashing a vertical light that is
followed 50-60 msec later by a horizontal light
produces the appearance of movement. The light
appears to move from vertical to horizontal
• Movement only perceived if delay was 50 – 60
msec
• The perceptual experience had properties the
individual components did not
• 1st Gestalt paper presented in 1912
Cognition, Sixth Edition, Robert J. Sternberg
Basic premise of Gestalt
psychology
Chapter 2
• Humans are not passive receivers of
sensory information. Our perceptions
are active, lively, and organized
• We actively organize perceptions into
coherent wholes – today the process is
referred to as top-down or
conceptually driven processing
Cognition, Sixth Edition, Robert J. Sternberg
Chapter 2
Scientific Method
• Gestalt perspectives on scientific method reflect
their acceptance of field physics as a model for
psychology.
– They emphasized the physical
environment.
– They used experience to guide analysis in
psychology.
– They started research with
phenomenological investigation.
– They accepted a broad range of methods
in psychology.
Cognition, Sixth Edition, Robert J. Sternberg
Chapter 2
Mind and Brain
•
Gestalt perspectives on mind and brain reject
reductionistic and linear models of mind.
–
–
–
–
Köhler argued for models of mind based in natural
systems.
He used models of mind based in the brain.
He described models in terms of free dynamics.
Köhler advocated isomorphism (ex. psychophysical
isomorphism).
•
There is a structural correspondence between experience
and underlying brain processes.
Cognition, Sixth Edition, Robert J. Sternberg
Chapter 2
Key terms in gestalt psychology:
Geographical versus behavioral
environment
• Geographical environment – the
physical world
• Behavioral environment – our
interpretation of the physical world
• Our interpretation or organization can
produce a behavioral world that is very
different from the physical world
• Illusions, dreaming, fantasies
Cognition, Sixth Edition, Robert J. Sternberg
Chapter 2
Gestalt’s View of Perception
• Basic tenet
– “The whole is more than a sum of its
parts”
• Law of Prägnanz
– Individuals organize their experience in
as simple, concise, symmetrical, and
complete manner as possible
Cognition, Sixth Edition, Robert J. Sternberg
Chapter 2
Cognition, Sixth Edition, Robert J. Sternberg
Chapter 2
Cognition, Sixth Edition, Robert J. Sternberg
Chapter 2
Perception is not just detection
• Perception is not just about detecting
color or shape.
• Perception is about organizing visual
information.
• How do we organize visual
information?
Cognition, Sixth Edition, Robert J. Sternberg
Müller-Lyer-illusion
Ponzo illusion
Chapter 2
Cognition, Sixth Edition, Robert J. Sternberg
Chapter 2
Or when do we fail to organize
visual information?
Cognition, Sixth Edition, Robert J. Sternberg
Chapter 2
Gestalt’s Principles of Visual Perception
Cognition, Sixth Edition, Robert J. Sternberg
Chapter 2
• Closure
Cognition, Sixth Edition, Robert J. Sternberg
Chapter 2
Gestalt’s Principles of Visual Perception
• Figure-ground
– Organize perceptions by
distinguishing between a figure
and a background
• Proximity
– Elements tend to be grouped
together according to their
nearness
• Similarity
– Items similar in some respect tend
to be grouped together
Cognition, Sixth Edition, Robert J. Sternberg
Chapter 2
The figure represents “some thing.”
The contours belong to the figure rather than to the
ground.
Cognition, Sixth Edition, Robert J. Sternberg
Chapter 2
Which one if the figure and which is the ground?
This is easy.
The figure tends to have solid and continuous surface.
Cognition, Sixth Edition, Robert J. Sternberg
Chapter 2
Gestalt’s Principles of Visual Perception
B
Continuity
Based on smooth continuity,
which is preferred to abrupt
changes of direction
Closure
Items are grouped together if
they tend to complete a figure
Symmetry
Prefer to perceive objects as
mirror images
A
D
C
Cognition, Sixth Edition, Robert J. Sternberg
Chapter 2
Cognition, Sixth Edition, Robert J. Sternberg
Chapter 2
Rules for Linking Contours
• Good continuation: group elements to
form smoothly continuing lines
Cognition, Sixth Edition, Robert J. Sternberg
Chapter 2
The Relatability Principle
Cognition, Sixth Edition, Robert J. Sternberg
Chapter 2
Meaning in the Edges
• Non-accidental features provide clues
to object structure
Cognition, Sixth Edition, Robert J. Sternberg
Chapter 2
Is the Whole Seen Before the
Parts?
• Global superiority effect (Navon, 1977)
Cognition, Sixth Edition, Robert J. Sternberg
Chapter 2
Complex listening: several
concurrent sound sources
• Auditory scene analysis
• “cocktail-party effect”
Cognition, Sixth Edition, Robert J. Sternberg
Chapter 2
Stream segregation
Cognition, Sixth Edition, Robert J. Sternberg
Chapter 2
Continuity
Cognition, Sixth Edition, Robert J. Sternberg
Chapter 2
Grouping by
similarity
Cognition, Sixth Edition, Robert J. Sternberg
Chapter 2
Tactile illusions
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Cognition, Sixth Edition, Robert J. Sternberg
Chapter 2
Depth Perception
• The ability to see the world in three
dimensions and detect distance
– Vision only has a two-dimensional view
– We must interpret the information given to
perceive depth
– We take flat images and create a threedimensional view
– Optical illusions demonstrate that this
interpretation does not always have to be
correct
Cognition, Sixth Edition, Robert J. Sternberg
Chapter 2
Monocular Depth Cues
• Texture gradients
– Grain of item
• Relative size
– Bigger is closer
• Interposition
– Closer are in front of other objects
Cognition, Sixth Edition, Robert J. Sternberg
Chapter 2
Monocular Depth Cues
• Linear perspective
– Parallel lines converge in distance
• Aerial perspective
– Images seem blurry farther away
• Motion parallax
– Objects get smaller at decreasing
speed in distance
Cognition, Sixth Edition, Robert J. Sternberg
Chapter 2
Binocular Depth Cues
• Binocular convergence
– Eyes turn inward as object moves
toward you; brain uses this
information to judge distance
• Binocular disparity
– Each eye views a slightly different
angle of an object; brain uses this to
create a 3D image
Cognition, Sixth Edition, Robert J. Sternberg
Chapter 2
Agnosias, Ataxias, & Cognition
• Demonstrate the modularity of
cognition
• Help us to understand what brain
locations are associated with
different types of higher-level
processing
• Provide us with a model of how
normal processing must work
Cognition, Sixth Edition, Robert J. Sternberg
Chapter 2
Deficits in Perception
• Disruption of the “what” pathway
– Inability to recognize and identify objects or
people, despite having knowledge of the
characteristics of the objects or people
• Disruption of the “how” pathway
• Cannot use vision to guide movement
• Unable to reach for items
Cognition, Sixth Edition, Robert J. Sternberg
Chapter 2
Fusiform Gyrus in Temporal
Lobe
• Implicated in pattern
recognition
• Studies illustrate it is
active in facial
recognition
• However, also active
if high expertise in
any item (birds, cars)
recognition
Cognition, Sixth Edition, Robert J. Sternberg
Chapter 2
Evidence for Separate Systems
• Prosopagnosia
– Inability to recognize faces after brain
damage
– Ability to recognize objects is intact
• Associative agnosia
– Difficulty with recognizing objects
– Can recognize faces
Cognition, Sixth Edition, Robert J. Sternberg
Chapter 2
Psychophysics
• the measurement of sensory
experiences
• Webers Law
Δφ = cφ
φ = Stimuli
• Fechners Law
Ψ = log φ Ψ = Sensation magnitude
Cognition, Sixth Edition, Robert J. Sternberg
Chapter 2
Perception or Attention
• Movement patterns / reflexes
• What cannot be unseen / heard
• Pop-out effect
• Change blindness
Cognition, Sixth Edition, Robert J. Sternberg
What you want to remember
• Perception is more than photons
and pressure.
• Perception is divided from
cognition/emotion but they are
often intertwined.
• Perception follows laws and
heuristics.
Chapter 2