visual imagery. visual imagery what is it? what’s it like? what’s it for?

Visual Imagery

Visual imagery

• What is it?

• What’s it like?

• What’s it for?

Imagery

• What shape are Snoopy’s ears?

• If you were driving from Gilmer to the corner and the gate was down, what would be the shortest detour?

• What color is a bee’s head?

• Is a leopard’s tail more than half the length of its body?

Imagery

Most people report “looking” at a mental picture to answer such

questions.

This implies (but doesn’t prove) that there is a type of representation that is quasi-pictorial, that is, has some of the properties of a picture.

Analog vs. proposition: “A ball is on a box”

on (ball,box)

Proposition• Relation• Syntax• Truth value• Abstract• Not spatial

Analog• No distinct relation• No syntax• Truth value only when

described• Concrete• Spatial medium

How do we know that there are images?

• Big controversy through the 1970’s

• Basic answer is that imagery has a lot of properties that you would predict it would have if it were quasi-pictorial, that propositions wouldn’t have.

Property 1: Rotation

Same (rotated)Or different (mirror)

Property 1: Rotation

Time to answer question related to angle of rotation: easy to interpret as imaging the pieces rotating.

Property 2: Size zooming

Property 2: size zooming

Property 3: Scanning

Property 3: Scanning

Property 4: Brain locus

Language centers

Visual centers

What’s imagery like?

In many ways, it’s like perception

(but in some ways not)

Memory representations

Visual experience “screen”

Early perceptual processes

Perky (1910)

Confusability (Perky, 1910)

People confused imagery and perception.

Like perception: Confusability (Perky, 1910)

Like perception: interference

High imagery: “A nudist devouring a bird”Low imagey: “The intellect of Einstein was a miracle”

Visual interfering task: subjects see a 1 or 2 on a computer screen & must say which digit not appear

Auditory interfering task: subjects hear a “1” or “2” and must say the other digit.

Control group: no task

Atwood, 1971

Atwood results

0

10

20

30

40

50

60

70

80

90

High Imagery Low Imagery

ControlVisualAuditory

visual interfering task = big effect on high imagery pairsauditory interfering task = big effect on low imagery pairs.

Visual

Spatial

Like perception: separation of “what” and “where”

color questions (“what color is the outside of a pineapple?”

size comparisons (“which is bigger, a popsicle or a pack of cigarettes?”)

Letter rotationMental scanning

Visual imagery: Spatial Imagery

Damage to ventral impairs visual imagery, damage to dorsal impairs spatial imagery

Imagery not like perception: distortions

• Which city is further North, Rome or Philadelphia?

• Which city is further East, Chicago, or Minneapolis?

• Which city is further South, Mexico City or Panama City?

• Which city is further west, Reno, or San Diego?

Imagery not like perception: distortion

Imagery not like perception: distortion

Reno

San Francisco

San Diego

65% of Bay Area students got it wrong

Imagery not like perception: distortion

Reno

San Francisco

San Diego

Tilted figures tend to be remembered as more vertical or horizontal than they really are

Imagery not like perception

Study this so that you could draw it.

Imagery not like perception

Before you draw it. . . Rotate it 90 degrees clockwise—can you tell what it is?

Now draw it.

Finke et al (1989)

Inspection allows you to determine what a visual image is.

Imagine the letter “B.” Rotate it 90 degrees counterclockwise. Put a triangle directly below it having the same width and pointing down. Remove the horizontal line. What is it?

Imagine the letter “B.” BRotate it 90 degrees counter clockwise.

B

Put a triangle directly below it having the same width and pointing down

B

Remove the horizontal line

People get the transformations right about 60% of the timeIf they get the transformations right, they name the image 60% of the time.

Image inspection

Images can be inspected to some extent, but it is not as effective as perception

What is imagery for?

• Memory

• Make implicit knowledge conscious

• Prepare for future actions

Memory

Concrete

Con

cre

te

Abstract

Ab

stra

ctFirs

t W

ord

Second Word

trumpet- potato

democracy- tire

shell- intellect

miracle- justice

Dual coding model (Paivio)Abstract nouns: can be coded only verbally.Concrete nouns: can be coded verbally or in terms of images.

Does bizarreness help?

It seems to; data conflict a bit from study to study, but overall answer seems to be “yes.”

Make implicit knowledge conscious

We are a visual species, and it makes sense for memory to follow

perception.

What might be ways to code the world other than vision?

Make implicit knowledge conscious

• Is the writing on the Coca-Cola logo cursive?

• Which is closer to the ground, the tip of a horse’s tail, or the knee on it’s back leg?

• Which is larger, a tennis ball, or the rounded part of a light bulb?

This is information that was in the image, and so can be extracted, but was not encoded, per se.

Example--will the bed fit in the alcove?

Prepare for future actions