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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


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


Imagery

  • Dual Coding Theory (Pavio, 1971)

Sensory Systems

representational

connections

Logogens (lexical entries)

Images

referential

connections

Verbal Processes

Non-Verbal Processes


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

  • Kosslyn(1973)

    • Mental scanning task

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

      • Locate another part of the object


Scanning Mental Images

  • Shepard and Metzler (1971)


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


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 Debate

Propositional Representation

Spatial (depictive ) Representation

“Sarah Palin

is on top of

the dinosaur.”


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 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 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 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 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 Images

  • Galiset al. (2004)

    • Spatial judgments about physical pictures or imagined pictures

    • Measured BOLD signals in an fMRI


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 Images?

  • Tversky (1981)

    • Subjects drew map of the

      western hemisphere, with certain

      cities

Miami

Santiago


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