Visual Imagery Visual imagery What is it Whats

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 quasipictorial, that is, has some of the properties of a picture.

Analog vs. proposition: “A ball is on a 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 Visual centers Language 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

Confusability (Perky, 1910) Perky (1910)

Like perception: Confusability (Perky, 1910) People confused imagery and perception.

Like perception: interference Atwood, 1971 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 results visual interfering task = big effect on high imagery pairs auditory interfering task = big effect on low imagery pairs.

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

Visual imagery: color questions (“what color is the outside of a pineapple? ” size comparisons (“which is bigger, a popsicle or a pack of cigarettes? ”) Spatial Imagery Letter rotation Mental scanning 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 65% of Bay Area students got it wrong Reno San Francisco San Diego

Imagery not like perception: distortion Tilted figures tend to be remembered as more vertical or horizontal than they really are Reno San Francisco San Diego

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?

Rotate it 90 degrees counter clockwise. B B Put a triangle directly below it having the same width and pointing down B Imagine the letter “B. ” Remove the horizontal line People get the transformations right about 60% of the time If 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

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 What might be ways to code the world other than vision? We are a visual species, and it makes sense for memory to follow perception.

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.

Prepare for future actions Example--will the bed fit in the alcove?