Myers’ PSYCHOLOGY

Chapter 6 Perception

What is Perception?

Plato – we perceive objects through our senses with our mind

Construct the outside world inside our heads Detect physical energy (bottom-up) and then

encode it into neural signals – this is SENSATION

We must then select, organize and interpret (top-down) our sensations – this is PERCEPTION

Perception Perceptions come at us

all the time The circles to the right

can be organized into several different images

Our minds switch back and forth

Our attention is selective

Selective Attention

Selective AttentionAwareness is like the beam of a

flashlight – only shines one certain areas at one time

In truth – we have a very limited aspect 11 billion bits of info at a time and we

can process 40 of them

Cocktail Party Effect

You have the ability to attend to only one voice among many

We are aware of other people and conversations but we cannot pay attention to them.

Our attention is divided

Multitasking?

Is there is a such thing as multi-tasking?

Do you think we can truly multi-tasking?

Let’s Listen: For your reference:

http://www.npr.org/player/v2/mediaPlayer.html?action=1&t=1&islist=false&id=95256794&m=95304837

Let’s test it!

“The Myth of Multitasking”

Follow the directions from the video using sheet that I have handed you

Write down how many seconds you are at off to the side when you finish each step

3 consequences Take longer Mistakes increase Stress increases Thoughts???? True???

http://davecrenshaw.com/multitasking-example/

Conclusions

Our attention is dividedWe cannot do 2 things at onceSwitching gears costs time and

results in mistakesInattentional blindness – failing to

see an object when our attention is directed elsewhere

Inattentional Blindness/Selective Attention

Video

Other Similar Phenomena

Change blindnessChange deafnessChoice blindnessChoice-blindness blindnessSee page 239 in book for more

explanation of these

Change Blindness

End Day 1

Perceptual Illusions

Illusions help us understand how we organize stimuli into meaningful perceptions

Have fascinated scientists for a long time

Which line is longer?AB or BC?

St. Louis ArchTaller than it is wide?

Visual Capture

Vision is our predominate senseWhen it competes with other senses

– it wins!

Perceptual Organization: Gestalt

To go from sensation to perception we must organize the information that we have received. How do we organize that information

Group of German scientists studied this Gestalt is German word for “form” or

“whole” We organize information by

integrating them into meaningful wholes

Taking a Look Backwards

Parts are 8 blue circles and white lines

When we view them together we see the cube

This is gestalt theory

Steps Needed to Form Perception

1. Figures and Ground – perceive an object as distinct from its surroundings

2. Grouping – Stimuli have to be grouped together based on basic features

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

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Perceptual Organization: Grouping Principles

Perceptual Organization: Closure

Gestalt grouping principles are at work here.

Perceptual Organization: Grouping Principles

Gestalt grouping principles are at work here.

Doghouse is NOT complete, but we perceive that it is

Closure and continuity

Perceptual Organization: Depth Perception

Depth Perception ability to see objects in three dimensions allows us to judge distance We see 2D and our minds transform it to 3D

Binocular cues (that help us perceive depth) Retinal disparity Convergence

Binocular Cues: Retinal Disparity and Convergence

Eyes are 2.5 inches apartRetina receives 2 slightly different imagesBrain compares the difference between them – aka

retinal disparity3D filmmakers exaggerate the retinal disparity by

manipulating camerasConvergence is a neuromuscular cue caused by the

way our eyes turn in when we view objects near usBrain notes angles of convergence and the more

inward strain the closer the object is

Monocular Cues

Monocular cues – available to each eye separately relative size

Further away = smaller interposition

If one object blocks another we perceive it as closer

relative clarity hazy object seen as more distant

texture coarse --> close fine --> distant

Monocular Cues 2 Relative Height - higher = farther

We pour less liquid into a tall, skinny glass than a short, fat glass

• We assume the tall glass holds more• St. Louis Arch explained by this?

Relative motion – as we move, objects that are stable appear to moveLooking at a car window

Linear Perspective – Parallel lines appear to converge with distance (railroad tracks)

Light and shadow Closer objects reflect more light Dimmer one seems further away

Day 3

Perceptual Constancy We must first perceive objects as having a distinct

form, location and motion Then…we must recognize the object without being

deceived by changes in shape, size, brightness, and color

Perceptual constancy allows us to do this Allows us to see an object is unchanging despite

changing stimuli Top-down process Identify things despite angle, distance, and illumination Information reaching your eyes has been sent to your

brain where neurons work together to extract the essential features that are then compared with stored images and identified

Perceptual Constancy

Shape and Size Constancies Even when the shape of an object seems to change

we perceive the original form of the familiar object Open door – no matter what angle we view it from –

we know it is a door Car – no matter the distance we are from it, we

know its relative size Size-Distance Relationship

Moon looks larger on the horizon than high in the sky

We can be lead astray (i.e. moon illusion)

Perceptual Organization

Perceptual Constancy

Light Constancy We perceive objects as having a

constant lightness even when illumination varies

Relative luminance – the amount of light an object reflects relative to its surroundingsSquares A and B are identical in

color, but B is received as lighterOur visual system computes

brightness and color relative to surroundings and context

Perceptual Organization and Other Senses Applies to other senses Why a ticking clock turns into a pattern Unfamiliar language we have trouble hearing when one

word turns to another and think that they just talk too fast

But we organize things to make sense THEDOGATEMEAT

What do you see? The dog ate meat? The do gate me at We go with what makes sense based on what we know

And the Debate Comes Again

Is perception nature or nurture?Do we learn to perceive?So…how important is experience and

how much does it shape our perceptual interpretations?

Sensory Deprivation and Restored Vision

If you are born blind and knew the difference between two items because of touch, when your vision was restored as an adult would you be able to see the difference between the 2 objects?

Studies suggest that there is a period for normal sensory and perceptual development

Nurture seems to sculpt what nature has endowed

Perceptual Adaptation

Perceptual adaptation is what makes the world seem normal again when sensory input changes

After getting new glass, one may feel disoriented for a few days, but then it adjusts within a few days

Perceptual Set

Experiences, assumptions, and expectations give us a perceptual set

Mental predisposition Once we have

formed the wrong idea – we have trouble seeing the reality

Schemas

Through experience we form concepts, or schemas

We use our schemas to interpret and organize unfamiliar information

When we face ambiguous moving objects in the sky, we use schemas to help us “process” it Different people have different schemas It’s a bird! It’s a plane! It’s Superman!

Facial recognition attuned to expressive eyes and mouths (see Madonna pic on pg 259)

Context Effects

A given stimuli may trigger radically different perceptions partly due to differing schemas, but also because of immediate context.

Our minds can work backwards in time to allow a later stimuli to determine how we receive and earlier one

Top down influences perception as much as bottom up does.

Emotional Contexts

Emotional contexts also color our social perception

If a team has a history of aggressive play, then referees who are told before will give more penalties than normal.

Experience helps construct perception So…nature or nurture? Both?

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

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 (mind over matter – levitating

a table)