Unit 4 Perception - PowerPoint Presentation

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Unit 4 Perception Perception pt. 2

http://www.psychologie.tu-dresden.de/i1/kaw/diverses%20Material/www.illusionworks.com/index.html

http://www.eyetricks.com/scary_optical_illusion2.htmSlide2

Difference Thresholds

Any smallest detectable change in a stimulus:How much does the volume have to increase before you can tell that the music playing from your stereo has become louder

How much do the laces on your hiking boots need to be loosened so that they feel slightly less tight

Can you notice the difference when you turn the volume up one bar on the TV?Slide3

Sub-Threshold

Subliminal

When stimuli are below one’s absolute threshold for conscious awareness

0

25

50

75

100

Low

Absolute

threshold

Medium

Intensity of stimulus

Percentage

of correct

detections

Subliminal

stimuliSlide4

Sensory Adaptation

Sensory Adaptation (Habituation) is diminished sensitivity to constant and unchanging stimulationOne example of sensory adaptation occurs when you dive into a swimming pool filled with cold water. At first, the water seems frigid, but if you stay in for a while you will eventually get used to it…

Can you think of another example of habituation?

How about when driving on the highway? Why don’t we feel our underwear all day? Slide5

Signal Detection Theory

Predicts

how and when we detect the presence of a faint stimulus (signal) amid background stimulation (noise)

Assumes

that there is no single absolute threshold

Detection

depends partly on person’sexperienceexpectationsmotivation

level

of fatigueSlide6

Signal Detection

How soon would you notice an incoming text? Fairly quickly if

You are expecting a particular messageIt is important that you detect it, and

You are alertSlide7

Stare at the black dot in the middle. You should see the outer edges of the circle fade away!

Troxler’s

fading

It occurs because even if our eyes move a little when we are fixating a point, away from that point, in the perception field, the movements aren’t large enough to observe other elements; in conclusion the neurons remain focused on the main object and our visual system doesn’t involve new ones for the other elements.Slide8
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Chapter 8

http://www.michaelbach.de/ot/

Are the red lines parallel?Slide10

http://www.thedesignwork.com/65-amazing-optical-illusion-pictures/Slide11
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http://www.michaelbach.de/ot/col_lilacChaser/index.htmlSlide13

Afterimages following bright lights or adapting stimuli of excessively longer alternating patterns (contingent perceptual aftereffect, CAE), are the effects on the eyes or brain of excessive stimulation of a specific type - brightness, tilt,

colour

, movement, and so on. The theory is that stimuli have individual dedicated neural paths in the visual outer wall of an organism for the early stages of visual processing; repetitive stimulation of only a few channels misleads the visual system.Slide14
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Young lady or Old lady?Slide17

What influences our perceptions?Slide18

'lateral inhibition' - the term used to describe the complex way in which the cells on the back of the retina respond to areas of black and white. There is, however, little point in explaining the theory. Why? Because a few years ago it was shown to be completely untrue, and thus the explanation for the illusion remains a mystery...Slide19

Context Effects

For example, if a constant noise was made and it was disrupted by the phrase, “ill is on the duck” your brain would most likely make “ill”, “bill.” All this change is meant to satisfy the perceptual set element of our brains. I myself have had stuff like this happen to me. Walking in on conversation or being distracted usually ends up with me hearing something different.

Context effect

is the influence that our environment plays on us intellectually, emotionally, and sometimes even physically.

 "Context" is close in meaning to "environment,"Slide20

Brain Games 1

http://www.youtube.com/watch?v=PN1NAiM55hU&feature=relatedSlide21

Auditory Illusions

If the sounds do not work click here for link.Slide22
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Amazingly the "blue" spirals actually have the same color as the green. In other words no blue exists in the illusion; it only exists in your mind.Slide25
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Perceptual Interpretation

Perceptual Adaptation

(vision) ability to adjust to an artificially displaced visual field

prism glasses

Perceptual Set

a mental predisposition to perceive one thing and not anotherSlide27

Perceptual Set: Schemas

What you see in the center is influenced by perceptual setSlide28

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Perceptual Organization

When vision competes with our other senses, vision usually wins – a phenomena called

visual capture.

How do we form meaningful perceptions from sensory information?

We organize it. Gestalt psychologists showed that a figure formed a “whole” different than its surroundings.Slide29

Proximity

Seeing 3 pair of lines in A

Similarity

Seeing columns of orange and red dots in B

Continuity

Seeing lines that connect 1 to 2 and 3 to 4 in C

ClosureSeeing a horse in D

Psychology, 4/e by Saul Kassin ©2004 Prentice Hall

Perceptual Organization

Gestalt Laws of GroupingSlide30
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Continuity

Continuation

 – Leads the eye along a path. The principles of continuation is used to lead the viewers attention to a certain area or to connect an object to a specific actionSlide33

Closure

 – The eyes fill in the missing gaps to make the image/object whole.Slide34

Proximity

Continuation

 – Leads the eye along a path. The principles of continuation is used to lead the viewers attention to a certain area or to connect an object to a specific actionSlide35
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Depth Perception is the ability to judge the distances of objects, which also allows us to see them in three dimensions

Visual Cliff

Depth perception enables us to judge distances.

Visual Cliff:

   E.J. Gibson and R.D. Walk  This tool was originally developed to determine if infants had developed depth perception. A visual cliff is created by connecting a transparent glass surface to an opaque patterned surface. The floor below has the same pattern as the opaque surface. This apparatus creates the visual illusion of a cliff, while protecting the subject from injury.

Innervisions

Later research has demonstrated, however, that children as young as three-months are able to perceive the visual cliff. Slide37
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How do we see depth?

MONOCULAR CUE—HOW IT WORKS

Aerial Perspective

Objects that are near seem crisper and clearer; far away objects appear fuzzier.

Height in Plane

Objects that are farther away appear higher in the visual scene.

Interposition

Objects that are nearer block objects that are farther away.

Linear Perspective

Lines that are parallel (e.g., railroad tracks) look like they come to a point in the distance. The farther the lines, the closer they are.

Motion Parallax

When you are moving and you fixate on a spot, objects closer to you than that spot appear to move in the direction opposite to your motion; objects farther than that spot appear to move in the same direction as you are moving.

Relative Size

If two objects are of the same size, the closer one is bigger.

MONOCULAR CUE—HOW IT WORKS

Aerial Perspective

Objects that are near seem crisper and clearer; far away objects appear fuzzier.Height in PlaneObjects that are farther away appear higher in the visual scene.

InterpositionObjects that are nearer block objects that are farther away.Linear Perspective

Lines that are parallel (e.g., railroad tracks) look like they come to a point in the distance. The farther the lines, the closer they are.Motion ParallaxWhen you are moving and you fixate on a spot, objects closer to you than that spot appear to move in the direction opposite to your motion; objects farther than that spot appear to move in the same direction as you are moving.

Relative SizeIf two objects are of the same size, the closer one is bigger.Slide39

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Binocular Cues:

Depth cues such as retinal disparity that depends on the use of two eyes.

Retinal disparity:

Images from the two eyes differ. Try looking at your two index fingers when pointing them towards each other half an inch apart and about 5 inches directly in front of your eyes. You will see a “finger sausage” as shown in the inset.Slide40

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Binocular Cues

Convergence:

Neuromuscular cues. When two eyes move inward (towards the nose) to see near objects and outward (away from the nose) to see faraway objects.Slide41

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Monocular Cues

Relative Size:

If two objects are similar in size, we perceive the one that casts a smaller retinal image to be farther away.Slide43

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Monocular Cues

Interposition:

Objects that occlude (block) other objects tend to be perceived as closer.

Rene Magritte,

The Blank Signature,

oil on canvas,

National Gallery of Art, Washington. Collection of

Mr. and Mrs. Paul Mellon. Photo by Richard

Carafelli

.Slide44

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Monocular Cues

Relative Clarity:

Because light from distant objects passes through more light than closer objects, we perceive hazy objects to be farther away than those objects that appear sharp and clear.Slide45

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Monocular Cues

Texture Gradient:

Indistinct (fine) texture signals an increasing distance.

© Eric Lessing/ Art Resource, NYSlide46

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Monocular Cues

Relative Height

:

We perceive objects that are higher in our field of vision to be farther away than those that are lower.

Image courtesy of Shaun P. Vecera, Ph. D.,

adapted from stimuli that appered in Vecrera et al., 2002Slide47

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Monocular Cues

Relative motion:

Objects closer to a fixation point move faster and in opposing direction to those objects that are farther away from a fixation point, moving slower and in the same direction. Slide48

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Monocular Cues

Linear Perspective:

Parallel lines, such as railroad tracks, appear to converge in the distance. The more the lines converge, the greater their perceived distance.

© The New Yorker Collection, 2002, Jack Ziegler

from cartoonbank.com. All rights reserved.Slide49

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Monocular Cues

Light and Shadow:

Nearby objects reflect more light into our eyes than more distant objects. Given two identical objects, the dimmer one appears to be farther away.

From “Perceiving Shape From Shading” by Vilayaur

S. Ramachandran. © 1988 by Scientific American, Inc.

All rights reserved.Slide50

Motion perception

Phi Phenomenon: with a succession of lights that creates the impression of, say, a moving arrow.Slide51

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Perceptual Constancy

Perceiving objects as unchanging even as illumination and retinal images change. Perceptual constancies include constancies of shape and size.

Shape ConstancySlide52

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Size-Distance Relationship

The distant monster (below, left) and the top red bar (below, right) appear bigger because of distance cues.

From Shepard, 1990

Alan Choisnet/ The Image Bank

Size Constancy:Slide53

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Perceptual Constancies

From Shepard, 1990

Alan Choisnet/ The Image Bank

Size Constancy:Slide54

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Perceptual Adaptation

Visual ability to adjust to an artificially displaced visual field, e.g., prism glasses.

Courtesy of Hubert DolezalSlide55

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Students recognized a caricature of Arnold Schwarzenegger faster than his actual photo.

Features on a Face

Face schemas are accentuated by specific features on the face.

Kieran Lee/ FaceLab, Department of Psychology,

University of Western AustraliaSlide56

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Eye & Mouth

Eyes and mouth play a dominant role in face recognition.

Courtesy of Christopher Tyler

Portrait artists understood the importance of this recognition and therefore centered an eye in their paintings.Slide57

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To an East African, the woman sitting is balancing a metal box on her head, while the family is sitting under a tree.

Cultural Context

Context instilled by culture also alters perception. Slide58

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

psychokinesisSlide59

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Claims of ESP

Telepathy:

Mind-to-mind communication. One person sending thoughts and the other receiving them.

Clairvoyance:

Perception of remote events, such as sensing a friend’s house on fire.

Precognition:

Perceiving future events, such as a political leader’s death.Slide60

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Premonitions or Pretensions?

Can psychics see the future? Can psychics aid police in identifying locations of dead bodies? What about psychic predictions of the famous Nostradamus?

The answers to these questions are NO! Nostradamus’ predictions are “retrofitted” to events that took place after his predictions.Slide61

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Putting ESP to Experimental Test

In an experiment with 28,000 individuals, Wiseman attempted to prove whether or not one can psychically influence or predict a coin toss. People were able to correctly influence or predict a coin toss 49.8% of the time.Slide62

Subliminal Stimulation

Below one’s absolute threshold for conscious awareness.Show clip

Does this work?

Yes and No

Slide studies showed some emotional reactivity

(called priming a response).

The effects are subtle and fleeting.