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

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 Kant- knowledge 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

Actualdescent

path

Pilot’s perceiveddescent path

Altitude looksthis much higher

20 18 16 14 12 10 8 6 4 2Distance from runway (miles)

10

8

6

4

2

0

Altitude(thousands

of feet)

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/demos.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