PERCEPTION
Philip G. Zimbardo, Richard J. Gerrig
in
Psychology and Life, HarperCollins
•  Your perception of the world
–  relies on more than just the
information arriving at your
sensory receptors.
•  Your ability to transform and
interpret sensory information
–  your ability to have what you
know interact with what you
see – allows you to recognize
Madonna, Oprah Winfrey, and
Bill Clinton
•  Sensation
–  is what gets the show started,
but something more is needed
to make a stimulus meaningful
and interesting and, most
important, to make it possible
for you to respond to it
effectively
•  The processes of perception
–  provide the extra layers of
interpretation that enable you
to navigate successfully
through your environment
The role of perception
•  Is to make sense of
sensation
A percept
•  Is what is perceived
(the phenomenological,
or experienced
outcome of the process
of perception)
Distal and proximal
stimulus (what we perceive and
previous used informations)
•  also for hearing, touch
and taste
•  E.g. the apple
1) Sensing,
•  The conversion of
physical energy into
neural codes
recognized by the
brain
2) Organizing
•  An internal
representation of an
object is formed
and a percept of the
external stimulus is
developed
3) Identifying and
recognizing
•  Assign meaning to
percepts
•  To identify and
recognize
•  involves higher level
cognitive processes:
•  theories, memories,
values, beliefs, and
attitudes concerning
the objects
•  Illusions
•  Shared by most
people in the same
perceptual situation
•  Also in hearing and
taste
[Hallucinations]
•  Non shared perceptual
distortions that
individuals experience
as a result of unusual
physical or mental
states
Approaches to the study of
Perception
•  Nature or Nurture (learn)?
•  Most modern theories agree that your experience
of the world consists of a combination of nature
and nurture. But these theories disagree on the
size of the portions that make up this combination
–  Helmholts’ Classical Theory (1866)
–  The Gestalt Approach: Koffka-1935,
Köhler-1947, Wertheimer-1923
–  The Gibson’s Ecological Optics (1966, 1079)
A Unified Theory of Perception
•  What are the physiological mechanism
involved in perception?
•  Stimulus-driven, or bottom-up processing, works its way up
the brain, while expectation-driven, or top-down processing,
complements it.
•  What is the process of perceiving?
•  Central role of Gestalt Theories and new approaches and
conceptual problem solving
•  What are the properties of the physical world
that allow you to perceive?
•  Gibson’s theory – the environment makes available certain
types of information and your perceptual apparatus is
innately prepared to recover that information
Attention Process
•  Your focus of attention
•  determines the types of information that will be
most readily available to your perceptual
processes
•  What types of environmental stimuli require your
attention and how attention contributes to your
experience of those stimuli?
•  How attention functions to selectively highlight
objects and events in your environment?
Selective Attention
•  Determining
the focus of
attention
•  goal-directed
selection
•  stimulusdriven
capture
The Fate of Unattended Information
•  The limited
capacity of
mind
•  The filter theory
The Fate of Unattended Information
•  Unattended
objects are
sufficiently
processed by
your perceptual
system
•  So that they
become less
available for
later use
Unattended information and
selective attention
•  The selective attention works in two ways:
•  First your internal representations of the stimuli on
which you have focused attention become
highlighted in memory
•  Second your internal representations of the
unattended stimuli are somewhat suppressed.
Preattentive Processing and
Guided Search
•  Preattentive processing
•  It operates on sensory inputs before you attend to
them, as they first come into the brain from the
sensory receptors.
•  Guided Search
•  serial / parallel search
•  putting features together
Organizational Processes in
Perception (1)
•  The Gestalt theorists argued that what you
perceive depends on laws of organization, or
simple rules by which you perceive shapes and
forms
Organizational Processes in
Perception (2)
•  Region Segregation:
•  The first task of perceptual organization is to find
coherent regions within the mosaic of responses
•  The primary information for the region segregation
process comes from color and texture
•  Figure
•  Ground
•  Closure
Organizational Processes in
Perception (3)
•  Shape: figural goodness and reference
frames
•  Our tendency to perceive stimuli as complete,
balanced, and symmetrical, even when there are
gaps, imbalance, or asymmetry
•  Figural goodness:
•  simplicity, symmetry, and regularity
•  Good figures are more easely and accurately
perceived, remembered, and described than bad
ones
Figural Goodness and
Reference Frames
Principles of Perceptual Grouping
•  Gestalt Psychologist [Max Wertheimer 1923]
•  Law of proximity
•  Law of similarity (color, size, shape, orientation)
•  Law of common fate
à Law of pregnanz (good figure)
à The whole percept is different from the mere
collection of its parts
Spatial and Temporal Integration
Motion perception
Depth Perception
Depth Perception
Depth Perception
Depth Perception
Perceptual Constancies
Perceptual Constancies
Identification and Recognition
Processes (1)
Identification and Recognition
Processes (2)
Identification and Recognition
Processes (3)
Identification and Recognition
Processes (4)
Identification and Recognition
Processes (5)