Perception- Part 2
Change Blindness
What does this say?
Call me….
703-855-78S2
Top-Down vs. Bottom Up
Re-Cap of Perspective:
Perceptual Constancy
• Perceptual Constancy- Tendency for perceptions of
objects to remain relatively unchanged in spite of
changes in raw sensations
– Brightness Constancy: piece of white paper does not
change when it moves from am dimly lit room to a brightly
lit room
– Color constancy: colors do not seem to change much in
spite of different conditions of light
– Size constancy: dollar bill from 1 foot and 10 feet with
seem different in size, however we do not perceive it as
different because familiar objects do not change in
perceived size as different distances
– Shape constancy- a penny seen straight on is circular, from
an angle it’s oval however we continue to perceive it as
circular
Perceptual Organization: Gestalt
 Visual Capture
 tendency for vision to dominate the other
senses
 Gestalt--an organized whole
 tendency to integrate pieces of information
into meaningful wholes
Perceptual Organization: Gestalt
 Grouping
 the perceptual tendency to organize stimuli into
coherent groups
 Grouping Principles
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proximity--group nearby figures together
similarity--group figures that are similar
continuity--perceive continuous patterns
closure--fill in gaps
connectedness--spots, lines, and areas are seen
as unit when connected
Re-Cap: Depth Perception
• Texture Gradient- texture of objects more severe up
close
• Linear Perspective- images cast smaller images on
retina when they are more distant, parallel lines appear
to grow closer further away
• Superposition- Closer objects tend to be partially in
front of distant objects
• Shadowing- shadow suggest depth of object
• Speed of movement- objects further away move across
the field vision slower
• Aerial Perspective- distant objects look hazy
• Accommodation- shape of lens of eye changes to focus
on visual images
Philosophers have debated the
origin of our perceptual abilities:
Is it nature or nurture?
What do you think?
Beliefs
• German philosopher Immanuel Kantknowledge comes from our inborn ways of
organizing sensory experience
• British philosopher John Locke- through our
experiences we also learn to perceive the
world
Could a person who is blind from birth
distinguish this visually if they gained
sight as an adult?
Critical Period
• Critical period of vision is at birth through
infancy of humans, cats, monkeys
Cataracts
• Definition: an eye disease in which the lens
becomes covered in an opaque film that
affects sight, eventually causing total loss of
sight.
Perceptual Adaption
• With vision, the ability to adjust to an
artificially displaced or even inverted visual
field
– Example: wearing a new pair of glasses (may be
fuzzy at first, a few hours or days, eyes will adjust)
Perception and the Human
Factor
 Human Factors Psychology
 explores how people and machines interact
 explores how machine and physical environments can be
adapted to human behaviors
Perceptual Set: Human Factors
10
Altitude
(thousands
of feet)
Pilot’s perceived
descent path
8
6
Altitude looks
this much higher
4
Actual
descent
path
2
0
20
18
16
14
12
10
8
6
4
Distance from runway (miles)
2
Is it really possible?
Is There Extrasensory
Perception?
 Extrasensory Perception
 controversial claim that perception can occur
apart from sensory input
 telepathy
 clairvoyance
 precognition
 Parapsychology
 the study of paranormal phenomena
 ESP
 psychokinesis
Claims of paranormal
phenomena include astrological
predictions, psychic healing,
communication with the dead,
and out-of-body experiences
ESP
Three types of ESP:
1. Telepathy- mind to mind communication
2. Clairvoyance- perceiving events as they are taking
place
3. Precognition- perceiving future events
Also associated with ESP, psychokinesis (“mind over
matter”
• http://viscog.beckman.illinois.edu/djs_lab/de
mos.html
• www.grand-illusions.com
• http://www.mindhacks.com/
• http://psych.hanover.edu/Krantz/tutor.html
• http://users.skynet.be/J.Beever/pave.htm
• http://philomel.com/musical_illusions/
• http://www.audiodesignline.com/204300429
Activity
• Take out a piece of paper and something to
write with
• On that piece of paper you are going to write
a paragraph about someone you know
-You may not choose a family member
- You may not use their name or how you
know them
- Identify how they have helped you learn
a life lesson