Perception
The process of organizing and interpreting information,
enabling us to recognize meaningful objects and events.
Selective Attention
• The focusing of conscious awareness on a
particular stimulus.
Cocktail-party phenomenon
• The “cocktail party effect”
describes the ability to
focus one's listening
attention on a single talker
among a mixture of
conversations and
background noises, ignoring
other conversations.
– Form of selective attention.
• Listening to music and
studying?
– Headphone activity.
Cell Phones and Driving?
• Texting while driving is
now the leading cause
of death among
teenagers – surpassing
drinking and driving.
• More than 3,000 teens
die each year in crashes
caused by texting while
driving.
Why?
• Turn to a partner and
explain from a
psychological theory,
why your reaction time
decreases by more than
35% when texting and
driving.
• How could we convince
teens not to text and
drive?
Inattentional Blindness
Try the following:
• Card Trick
• Basketball Game
Inattentional Blindness
• Failing to see visible
objects when our
attention is directed
elsewhere.
• Look at the FedEx
truck in the next
picture. See anything?
• Now look again at the
next photo. See if you
notice it now.
Show Brain Games “Pay Attention” (0-9:00)
Illusions
Ames Room
Illusions of Perceived Size-Distance
Parked Cars
Ponzo Illusion
Illusions of Perceived Size-Distance
Muller-Lyer Illusion
Illusions of Perceived Size-Distance
Horizon Moon
Illusions of Size-Distance Relationship
High moon on
a clear night.
Other Illusions
"Optical illusion disc
(1833) which is spun
displaying the illusion of
motion of a ball with a
wedge-shaped piece
missing passing through
a hoop and of a monkey
swinging on branches of
a tree and a zebra
jumping through an
opening between two
trees in a circle at the
outer edge of the disc."
Gestalt Psychology
• Gestalt means “an organized whole.”
• These psychologists emphasize our tendency to
integrate pieces of information into meaningful
wholes.
Gestalt Psychology
• To perceive forms, we must
organize the visual field into
objects (figures) that stand
out from their surroundings
(ground).
• This is figure-ground
perception.
Gestalt Psychology
• Gestalt psychologists focused on how we GROUP objects
together.
• We innately look at things in groups and not as isolated
elements. A form of Top-Down Processing.
• Proximity (group objects that are close together as being
part of same group).
• Similarity (objects similar in appearance are perceived as
being part of same group).
• Continuity (objects that form a continuous form are
perceived as same group).
• Closure (we fill gaps in if we can recognize it).
• Marching Band Example
Gestalt Psychology
Depth Perception
• The ability to see objects in three dimensions
although the images that strike the retina are
two dimensional.
• Allows us to judge distance.
Depth Cues
• Eleanor Gibson and her
Visual Cliff Experiment
for depth perception.
• If you are old enough to
crawl, you are old enough
to perceive depth.
• We see depth by using
two cues that
researchers have put in
two categories:
• Monocular Cues
• Binocular Cues
Monocular Cues
• You really only
need ONE eye to
use these (used by
artists to show
depth).
• Linear Perspective
• Interposition
• Relative size
• Texture gradient
• Relative Motion
Monocular Cues
• Interposition: if something is blocking
our view, we perceive it as closer.
• Relative Size: if we know that two objects
are similar in size, the one that looks smaller
is farther away.
• Linear Perspective: parallel lines
seem to converge with distance.
Monocular Cues
• Texture Gradient: the coarser it looks
the closer it is.
• Relative Motion: things that are closer
appear to move more quickly.
Binocular Cues
• We need BOTH of our
eyes to use these cues.
• Retinal Disparity - as an
object comes closer to us,
the differences in images
between our eyes becomes
greater (Like the Sausage
Finger trick).
• Convergence - degree to
which our eyes turn inward
to focus on an object.
Motion Perception
• Stroboscopic effect
(flip book effect).
• Phi phenomenon
(blinking neon lights;
like the marquee in
front of the school).
Perceptual Constancy
• Perceiving objects as unchanging even as
illumination and retinal images changes.
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Types of Constancy
Shape Constancy
Size Constancy
Lightness Constancy
(ex. A white piece of
paper indoors reflects
considerably less light
than does a black lump of
coal outside on a bright,
sunny day. Yet the paper
looks white, and the coal
black.)
Sensory Deprivation
• What happens when vision is restricted
from birth?
• If their sight is restored, they can
perceive figure from ground and colors, but
they lack the experience to recognize
shapes, forms and complete faces.
• Critical Period – for some aspects of
sensory and perceptual development.
Perceptual Adaptation
• In vision, the ability to adjust to an
artificially displaced or even
inverted visual field.
Perceptual Set
• Mental predisposition to perceive
one thing and not another.
• What you see in the center
picture is influenced by a
perceptual set. Based on schemas.
Face Schemas
• The famous Mona Lisa . . . frown or smile?
Context Effects
• Based on the immediate context.
• How you perceive the box in the
following picture depends on the
context defined by the rabbits.
Human Factors Psychology
• Human factors
psychologists help
others by:
• Developing products that
maximize usability.
• Working to improve
worker safety and
efficiency.
Extrasensory Perception
• Extrasensory perception (ESP): the
ability to perceive events without
using normal sensory receptors.
• Parapsychology: the field that studies
ESP and other paranormal phenomena.
Types of ESP
– Telepathy: the ability to read minds
– Clairvoyance: the ability to perceive
objects or events
– Precognition: the ability to predict the
future
– Psychokinesis: the ability to move objects
There Is Little Scientific Evidence
for Extrasensory Perception
• Reasons for skepticism:
– Many published ESP studies have used
flawed research methodologies or failed to
detect outright fraud by those they were
testing.