Perception
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Perception
The process of selecting, organizing, and
interpreting sensory information, which enables us
to recognize meaningful objects and events.
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Selective Attention
Perceptions about objects change from moment to moment.
We can only focus on limited aspects of sensory input at
any given time
e.g. : “Cocktail Party Effect”
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Perceptual Illusions
Illusions provide good examples in
understanding how perception is organized.
Studying faulty perception is as important as
studying other perceptual phenomena.
Line AB is longer than line BC.
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Tall Arch
Rick Friedman/ Black Star
In this picture, the
vertical dimension
of the arch looks
longer than the
horizontal
dimension.
However, both are
equal.
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Perceptual Organization
How do we form meaningful perceptions
from sensory information?
We organize it. Gestalt psychologists
showed that a figure formed a “whole”
different than its surroundings.
called a “gestalt”
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Form Perception
Organization of the visual field into objects
(figures) that stand out from their surroundings
(ground).
Time Savings Suggestion, © 2003 Roger Sheperd.
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Perception in Brain

Our perceptions are a combination of
sensory (bottom-up) and cognitive (topdown) processes.
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Perceptual Interpretation
Immanuel Kant (1724-1804) maintained that
knowledge comes from our inborn ways of
organizing sensory experiences.
John Locke (1632-1704) argued that we learn to
perceive the world through our experiences.
How important is experience in shaping our
perceptual interpretation?
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Sensory Deprivation
Kittens raised
without exposure to
horizontal lines later
had difficulty
perceiving horizontal
bars.
Blakemore & Cooper (1970)
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Perceptual Set
Other examples of perceptual set.
Dick Ruhl
Frank Searle, photo Adams/ Corbis-Sygma
(a) Loch ness monster or a tree trunk;
(b) Flying saucers or clouds?
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Cultural Context
Context instilled by culture also alters
perception.
To an East African, the woman sitting is balancing a metal
box on her head, while the family is sitting under a tree.
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Perception Revisited
Is perception innate or acquired?
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The following factor(s) affect our detection of
weak signals:
a.
b.
c.
d.
e.
motivation
fatigue
expectations
all of the above
b & c but not a
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With respect to sensation and perception, it is fair
to say that :
a. experience plays no role
b. perception does not appear to involve any
inborn perceptual capacities
c. humans experience external stimuli as they are
with little processing by the brain
d. none of the above
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