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)