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Perception
The process of organizing and interpreting information, enabling us to recognize
meaningful objects and events.
• At any moment our awareness focuses, like a
flashlight beam, on only a limited aspect of all
that we experience.
• Inattentional blindness – failing to see visible
objects when our attention is directed
elsewhere. Awareness Test
– Change blindness
– Change deafness
– NBC news clip
– Pop-out phenomenon – something strikingly
different & stands out.
Selective Attention
Selective Attention: Cocktail-party phenomenon
• The cocktail party effectdescribes 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.
Auditory Illusions
If the sounds do not work click here for link.
Perceptual Illusions
• visual capture: when vision competes against
other senses, vision usually wins.
• Example: watching a movie, sound coming
from behind us in a theater. We perceive the
people on screen as talking, making the noise,
because our vision overpowers our hearing.
Perceiving Images
The first step in perceiving
an image is determining
the figure and ground.
organization of the visual
field into objects
(figures) that stand out
from their surroundings
(ground)
Gestalt and the Urge to Organize
Gestalt Psychology• Gestalt psychologists focused on
how we GROUP objects together.
• We innately look at things in groups and not as isolated elements.
• 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 (like top-down processing…we fill gaps in if we can recognize it)
http://graphicdesign.spokanefalls.edu/tutorials/process/gestaltprinciples/gestaltprinc.htm
Motion PerceptionHow does the brain recognize an object is moving?
How does it interpret the direction of movement?
Brain interprets shrinking
objects as receding
and enlarging objects
as approaching
Stroboscopic Effect
the perception of motion
produced by a rapid succession of
slightly varying images (animation,
movies)
Phi phenomenon
an illusion created when two or
more adjacent lights blink on and
off in succession, creating the
perception of movement (lighted
signs, illusions)
Perceptual Constancythe ability to perceive an object is the same even as the illumination and
retinal image changes.
Shape Constancy- perception that shape of an object
doesn’t change just because image on the retina
does.
Perceptual Constancy
• Size constancy – perception that an object’s
size remain the same even as the retinal
image changes.
• Color Constancy – the perception that familiar
objects have a consistent color, even if
changing illuminations alter the wavelength
reflected.
Perceptual Constancy
Lightness constancy – the perception that
familiar objects have a constant lightness,
even while illumination varies.
Visual Cliff – used to check for depth
perception. (Gibson & Walk, 1960)
Depth Perception
• Monocular Depth Cues
– Linear perspective (parallel lines appears to converge on a vanishing point)
– Relative height (more distant objects are higher)
– Relative size (more distant objects are smaller)
Depth Perception
• Monocular Depth Cues
– Relative clarity (objects
in the distance appear
hazy)
– Overlap/interposition
(continuous outlines
appear closer)
Depth Perception
• Monocular Depth Cues
– Texture gradient
(texture details, like
roughness, diminish
with distance)
Depth Perception
• Monocular Depth Cues
– Light and shadow
How many monocular depth cues
can you identify here?
HOMEWORK:
• Draw a picture that incorporates at least four
monocular depth cues as discussed in the
book and lecture. Label the monocular depth
cues in your drawing.
Depth Perception
• Monocular Depth Cue
– Motion parallax (or relative motion) – Distant
objects will appear slow in comparison with close
objects even when the two are moving at the
same speed
– Think of an airplane traveling overhead.
Depth Perception
• Binocular depth cues – require two eyes
– Retinal disparity – the greater the difference
between the images on your two retina, the closer
the object (“camera 1, camera 2”, “finger
sausage”, hole in the hand)
– Convergence – the greater your eye muscles must
strain (or converge) to focus on an object, the
closer the object (notice how hard your eyes
strain when you focus on the tip of your nose).
Size-distance relationship
When other monocular cues tell us
an image is further away, it actually
appears larger.
Moon illusion
� Perceptual Set
� a mental predisposition to perceive
one thing and not another
What do you see?
SCHEMAS
• our perceptual set is developed through
schemas, the concepts that we form through
experiences. They help us organize our
perceptions. If an atheist or Buddhist saw that
wall, they’d probably see nothing. A devout
Christian would be more likely to see virgin
mary.
FUN with Perceptual Sets
-Our EXPERIENCE shapes our perceptions
FUN with Perceptual Sets
-Our EXPERIENCE shapes our perceptions
FUN with Perceptual Sets
-Our EXPERIENCE shapes our perceptions
• TIME FLIES I CANT THEYRE TOO FAST
MacDonald MacHenry MacMahon
Machinery
�FOLK CROAK SOAK
FUN with Perceptual Sets
-Our EXPERIENCE shapes our perceptions
Context Effects
Extrasensory Perception
• Telepathy – mind reading
• Clairvoyance – perceiving remote events
• Precognition – Knowing things before they
happen
• Telekinesis (psychokinesis) – moving objects
with one’s mind (not technically ESP)