Mental Imagery

Chapter 10

Historical Overview

3 basic ages of mental imagery: – the prescientific period known as the

philosophic period – the measurement period – the cognitive and neurocognitive period

Current debate...

Is visual imagery really visual or is it governed by general-purpose cognitive processes?– When I “image” a tree, the same (or very

similar) neurons/processes are activated as when I originally saw the tree

– Representations used in imagery are not the same as those used in real perceptions.

3 Theories...

1. Pavio’s Dual-Coding Hypothesis

2. Conceptual-Propositional Hypothesis

3. Functional-Equivalency hypothesis

Paivio's Dual-Coding Theory The basic tenant of this theory is that

information is mentally represented either in a verbal system or a nonverbal (analogical) system (or both).– Each system contains different kinds of information.

– Each concept is connected to other related concepts in the same system and the other system.

– Activating any one concept also leads to activation of closely related concepts.

Basic Result: Paivio (1971)

Give S's a long list of pictures or words to remember.

Later, test memory with either a recall or recognition memory test. – S's recall more pictures than words.

Basic Result: Paivio (1971)

Explanations:

1) The Imagen system has superior memory abilities to the Logogen system.

2) Representing ideas in both systems is superior to representing ideas in only one system.

Basic Result: Paivio (1971) which of the explanations is correct?

– Compare: • Memory for Verbalizable and Nonverbalizable

pictures. • High-Imagability words (e.g., DESK) and Low-

Imagability words (e.g., EFFORT). • S's instructed to form mental images of words

and S's not instructed to form images of words. Results: Across all these situations, the

evidence consistently supports claim that having two representations = superior memory.

Can using dual coding ever interfere with/disrupt memory? Schooler & Engstrom-Schooler (1990)

– S's are shown a videotaped robbery. (This creates a visual memory.)

– S's then either: 1) Are asked to imagine the robber.

2) Are asked to describe the robber.

3) Are asked to do a series of math problems.

– S's complete a recognition memory test picking the robber out of a lineup of eight persons.

Results:Creating two codes can disrupt memory for information that is only represented in one code.

Another example: Wilson & Schooler (1991)

S's tasted different kinds of strawberry jam and either:– thought about it's taste– described it's taste.

S's then rated the quality of each jam.

conceptual-propositional hypothesis (Anderson and Bower) Taking conservation approach, claimed

wasn’t scientifically viable to suggest that memories are carried in memory like photos

conceptual-propositional hypothesis (Anderson and Bower) we store interpretations of events,

whether they be verbal or visual, rather than the imaginal components. – Anderson and Bower explain that concrete

concepts are coded by a rich set of predicates that bind concepts together. ..."the only difference between the internal representation for a linguistic input and a memory image is detail of information"

conceptual-propositional hypothesis (Anderson and Bower) Anderson and Bower’s conceptual-

propositional hypothesis is a good model theoretically – The hypothesis does have trouble

accounting for some imaginal processes

Functional-equivalency

The functional-equivalency hypothesis was first proposed by Shepard and Kosslyn and states that imagery and perception are extremely similar. – Shepard and Kosslyn introduced mental

rotation of visual stimuli in memory. • Relationship between time required for a

specific mental rotation and the actual degrees of rotation

Functional-equivalency

Conclusion… Visual images reflect internal

representations that operate in a way that is analogous to the functioning of the perception of physical objects.

Neurocogntitive Evidence Many studies haven been done to

obtain neurocognitive evidence for supporting the concept of mental imagery. – People who have damage to the left

hemisphere have trouble with verbal memory while patients with damage to the right hemisphere have trouble with visual material.

findings support dual-coding hypothesis

Neurocogntitive Evidence

– Different areas of brain are associated with different cognitive tasks

– visual imaginal tasks and vision seem to be situated in similar locations in the brain

– visual imaginal tasks, which require associative knowledge, activate brain regions affiliated with memory and vision

Support functional-equivalency

cognitive map

a map that allows us to navigate through the world. – Thorndyke and Hays-Roth (1982) found

two types of knowledge that are used in moving about from day to day:Route Knowledge and Survey Knowledge.

cognitive map Route knowledge is the knowledge that

we draw on for getting around. – If I gave someone directions to my house, I

am using Route Knowledge. Survey Knowledge is knowledge that

allows us to know understand the general spatial relationships that are involved.– I could tell the person that my house was

south of the University.

cognitive map

Mental maps tend to be biased by the person drawing them. – In a map drawn by a student in Australia,

the Australian continent was at the top of the map instead of the bottom.

Synesthesia: The Sound of Colors Synesthesia is a condition where

sensations usually experienced in a single modality are experienced in two modalities. – This conditiongive psychologists some very

interesting data and research. – Some examples of synesthesia are

receiving an auditory signal or sensation in a visual modality, where it obviously shouldn’t be.

Synesthesia: The Sound of Colors

Seeing the words to OVER THE RAINBOW, a form of synesthesia.