Perception
 How


do we define it?
How we recognize and interpret stimuli
Top down processing…
 Remember,
expectations and previous
experiences play an influential role…
Selective Attention
 Our
senses can take in approximately
11,000 bits of information at a time
BUT…
We can only focus on one thing at a time…
Neisser’s Basketball Study
 Inattentional



Blindness
Focusing on one stimulus prevents us from
noticing others
The dancing gorilla (bear)
Texting and driving!
2 readers, one listener….
 Cocktail

Party Effect
Can listen to only one voice at a time
• Can notice gender
• Can detect name
Just how much do we notice?
 Change

blindness
We fail to notice changes in our environment
(when we are focusing on something else)
Pop Outs!
 Striking
distinctions grab our attention
Perceptual Illusions
 Mislead
us by playing on the way we
organize and interpret our sensations
(challenges our schema!)
 Reveal how we normally organize our
sensations (thus clues to mechanisms of
perception)

Visual Capture: Vision is our dominant sense
(effects how we perceive our other senses)
• McGurk Effect (Youtube/edu)
Perceptual Organization
 Visual Agnosia
 See
all parts of an image, but not the
whole, (or meaning)
Gestalt (“form”)
 “The
whole is greater than the sum of its
parts”


We tend to see, or group images as a whole,
not as individual or isolated parts
A natural, or innate form of perception
Gestalt: (How we group objects)
 Figure
and ground (sometimes can be
reversible)
Gestalt
 Proximity
Gestalt
 Similarity
Gestalt
 Continuity
Gestalt
 Closure
Depth Perception
 Binocular


Cues (interplay of two eyes)
Retinal Disparity: each eye sees object from
slightly different angle (brain computes
difference in vision to judge depth)
Convergence: eyes move together as item
gets closer (brain detects convergence of
eyes as measure of depth)
 The
Finger Sausage!
Depth Perception
 Monocular
Cues
 Relative Size
Monocular Cues
 Linear
perspective
Monocular Cues
 Texture
gradient
Monocular Cues
 Interposition
Monocular Cues
 Relative
Height
Monocular Cues
 Relative
Clarity
Monocular Cues
 Relative
Motion (The faster it moves…)
Monocular Cues
 Light
and Shadow
Motion Perception
 Phi
Phenomenon
 Troxler
Effect
 With loss of sight- motion is usually first to
be restored
Perceptual Constancy
 Perceiving
an object as unchanging
despite a change in stimulus
 Key factors: Experience, Expectation
(Rules of perception)
 Size

Constancy:
As stimulus changes, we literally see
changing size, but we know size has not
changed due to experience and context of
objects surroundings
Size Constancy
http://www.eruptingmind.com/depth-perception-cues-other-forms-of-perception/
Shape Constancy
 We
know shape is constant even though
our angle and thus vision of object
changes
Lightness (Color) Constancy
 We
see objects as having consistent color,
even as changing conditions alter the
wavelength reflecting off the object.
http://www.psy.ritsumei.ac.jp/~akitaoka/light5e.html
Perceptual Set
 “To
believe it is to see it”
 A mental predisposition

Experiences give us a perceptual set, or
assumptions that influence how or what we
see…
Context Effect
 The
context in which a stimulus appears
affects how we perceive it…


“…eel is on the wagon.”
“…eel is on the orange.”
Sensory Deprivation / Restored Vision
 Adults
with vision for first time (cataract
surgery)



Have Sense of colors, detect figure from
ground
No depth perception, no perceptual
constancy (cortical cells not developed)
*Much of perception is learned during
critical period in early development
Perceptual Adaptation
 Our
perception can adapt to change in
stimuli, environment
 Inverted
goggles!!
Perceptual Constancy
pages 250-262
 Shape
constancy
 Size constancy
 Light constancy
 Sensory
Deprivation and Restored Vision
 Perceptual Adaptation
 Perceptual Set
 Context Effects