Visual imagery
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Visual Imagery. Imagery. Forming a picture in the mind without sensory input Mental imagery Visual imagery Paivio , Smyth and Yuille (1968 ) Subject studied word-pairs with each member varying in imagery High-High ( H-H ) High-Low ( H-L ) Low-High ( L-H ) Low-Low ( L-L )

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Visual Imagery

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Visual imagery

Visual Imagery


Imagery

Imagery

  • Forming a picture in the mind without sensory input

    • Mental imagery

    • Visual imagery

  • Paivio, Smyth and Yuille (1968)

    • Subject studied word-pairs with each member varying in imagery

      • High-High (H-H)

      • High-Low (H-L)

      • Low-High (L-H)

      • Low-Low (L-L)

    • Concrete words were

      remembered better than

      abstract words


Imagery1

Imagery

  • Dual Coding Theory (Pavio, 1971)

Sensory Systems

representational

connections

Logogens (lexical entries)

Images

referential

connections

Verbal Processes

Non-Verbal Processes


Imagery2

Imagery

  • Are visual images different from verbal codes?

  • Kosslyn (1975)

    • Sentence verification task [A 1 has 2 . ]

    • Semantic association between 1 and 2 varied

      • A mouse has a back.

      • A mouse has whisker.

    • Subject told to for mental image of object or not


Scanning mental images

Scanning Mental Images

  • Kosslyn(1973)

    • Mental scanning task

      • Focus on part of a mental image (or real picture)

      • Locate another part of the object


Scanning mental images1

Scanning Mental Images

  • Shepard and Metzler (1971)


Imagery debate

Imagery Debate

  • Do mental images exist?

  • Can we actually scan them, like a real picture?

  • Tacit knowledge explanation

    • Subjects may behave how they think that they should

    • Subjects unconsciously use knowledge of spatial relations

  • ZenonPylyshyn

    • Are visual images supported by spatial relationships or propositional relationships?

    • Spatial, or depictive, relationships

    • Propositional relationships


Imagery debate1

REAR DECK

CABIN

FRONT DECK

(behind)

(behind)

(rear of)

(top front of)

(side of)

(attached to)

MOTOR

WINSHIELD

PORTHOLE

ANCHOR

(bottom of)

(front of)

PROPELLER

HANDLE

Imagery Debate

  • Propositional theory (Pylyshyn, 1973)

    • Mental images are stored as propositions between parts

      • “All knowledge, including spatial knowledge and memory for images, can be expressed in semantically-based propositions.”

      • Explains mental scanning results of Kosslyn (1973)

*each link-node is a propositional relationship


Imagery debate2

Imagery Debate

Propositional Representation

Spatial (depictive ) Representation

“Sarah Palin

is on top of

the dinosaur.”


Evidence for spatial relations in mental images

Evidence for Spatial Relations in Mental Images

  • To show evidence for spatial relations

    • Performance (RTs) must vary as a function of distance

    • Distances cannot be confounded with propositional links

  • Kosslyn, Ball and Reiser (1978)

    • Subjects encode a map into memory

    • Scan between two points

      • Spatial relationships prediction?

      • Propositional theory prediction?


Evidence for spatial relations in mental images1

Evidence for Spatial Relations in Mental Images

  • Kosslyn, Ball and Reiser (1978)

    • Scanning time linearly related to the distance between points

    • Evidence favors spatial relations


Evidence for spatial relations in mental images2

Evidence for Spatial Relations in Mental Images

  • Kosslyn (1975)

    • Does size of mental image influence judgments of features?

    • Imagine animals side-by side and answer questions about one

      • Spatial relationships prediction?

      • Propositional theory prediction?


Evidence for spatial relations in mental images3

Evidence for Spatial Relations in Mental Images

  • Kosslyn (1975) Results

    • RTs were influenced

      by size of objects in the

      ‘mental visual field’

    • Features more distinct


Evidence for spatial relations in mental images4

Evidence for Spatial Relations in Mental Images

  • Neural Evidence?

    • LeBihanet al. (1993)

      • Perception and imagery

        activate visual cortex

      • Increased cerebral blood flow

        in visual cortex when mentally

        scanning


Evidence for spatial relations in mental images5

Evidence for Spatial Relations in Mental Images

  • Galiset al. (2004)

    • Spatial judgments about physical pictures or imagined pictures

    • Measured BOLD signals in an fMRI


How accurate are mental images

How Accurate are Mental Images?

  • Relational information is distorted in mental maps

  • Stevens & Coupe (1978)

    • Asked subjects about where one geographical location was with respect to another

      • Example: Is San Diego east

        or west of Reno, Nevada?


How accurate are mental images1

How Accurate are Mental Images?

  • Tversky (1981)

    • Subjects drew map of the

      western hemisphere, with certain

      cities

Miami

Santiago


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