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Cognitive Processes PSY 334. Chapter 4 – Perception-Based Knowledge Representation. Midterm Results . Top score = 40 Top score for curve = 40. Verbal Imagery vs Visual Imagery. The mind operates upon internal representations of knowledge.

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Cognitive Processes PSY 334

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Cognitive ProcessesPSY 334

Chapter 4 – Perception-Based Knowledge Representation

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Midterm Results

Top score = 40 Top score for curve = 40

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Verbal Imagery vs Visual Imagery

  • The mind operates upon internal representations of knowledge.

  • How is visual information (imagery) represented in memory?

  • Paivio’s Dual-Code Theory – memory is better if we encode information visually and verbally.

    • Separate representations are maintained for verbal and visual information.

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Behavioral Evidence for Dual Codes

  • Santa compared linear and spatial arrays of:

    • Three geometric objects

    • Three names of geometric objects

  • Subjects were asked whether the arrays contained the same objects or names.

  • Subjects were faster when shapes were in the same spatial arrangement but faster when words were linear.

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Santa’s Results

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Evidence From Brain Imaging

  • Subjects were asked to mentally rehearse:

    • A word jingle

    • Navigating their neighborhood

  • Increased blood flow occurred in different areas of the brain, depending upon the task.

  • The same brain areas were active as when actually speaking or seeing.

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Brain Evidence for Dual Codes

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Mental Rotation

  • Shepard – two-dimensional and three-dimensional mental images are rotated in the same way as actual objects.

    • The more an object is rotated, the longer it takes to respond in a same/different task.

  • Georgopoulos et al. – measured neurons firing in monkey brains when moving a handle.

    • Intermediate cells fire showing rotation.

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Shepard & Metzler’s Results



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Image Scanning

  • Brooks – subjects scanned imagined diagrams (like letter F) and noted outside corners, or sentences noting nouns.

    • Respond by saying “yes” or “no”

    • Tap left hand for “yes,” right hand for “no”

    • Point to Y or N on a sheet

  • Scanning a sheet for Y’s & N’s conflicted with scanning the mental image.

    • Conflict is spatial not visual.

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Mentally imagine the F and scan the outline beginning at the *.

Point to Y if an outside corner is present or N if not.

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Pointing Was Slowest

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Comparing Visual Quantities

  • Time to make a judgment decreases as the difference in size between objects increases.

    • The smaller the difference the longer it takes to make a judgment.

  • Which is larger:

    • moose or roach, wolf or lion?

  • The same pattern emerges when asked to judge actual differences, line lengths.

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Which is bigger?

The closer in size, two animals are, the longer it takes to decide which is bigger.

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Two Types of Imagery

  • Images involving visual properties (what) -- impaired with temporal damage.

  • Images involving spatial properties (where) – impaired with parietal damage.

  • Bilateral temporal lobe damage:

    • Difficulty judging color, size, shape.

    • No deficit in mental rotation, image or letter scanning, judgment of relative positions.

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Are Images Like Perception?

  • A series of experiments to compare perception and imagery:

    • Imagining transformations of mental images vs perceived stimuli.

    • Ponzo illusions occur with imagery.

    • Difficulty with reversible figures – depends on instructions, harder.

  • MRI plots show same brain activity.

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Similar Brain Activity

Fusiform face area

Parahippocampal place area

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Is Imagery Epiphenomenal?

  • Does imagery play a functional role in thinking or is it a subjective side-effect?

  • Kosslyn et al. showed that subjects could make judgments about arrays held in mind:

    • Which has longer stripes?

    • Visual regions (V17)became active duringimagery.

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Cognitive Maps

  • Two kinds of maps:

    • Route map – indicates places and turns, but not all landmarks.

    • Survey map – shows all relevant portions of space, not just route.

  • Adults produce survey maps, kids produce route maps.

  • Survey maps more versatile.

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  • Disneyland to Cal Poly Pomona via Yahoo Maps


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  • Navigation is complicated by the need to tie together different kinds of mental representations.

  • Egocentric representation – space “as we see it”

  • Allocentric representation – not specific to a particular viewpoint

    • Most maps are allocentric

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Types of Representations



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Thinking About Maps

  • People rotate physical maps to fit their egocentric perspective.

    • When the map itself cannot be rotated, extra processing time shows that people rotate an image of the map in their heads.

  • Cognitive maps show no orientation effects.

  • Allocentric representations are maintained by the hippocampus.

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Map Distortions

  • Which is farther east: San Diego or Reno?

  • People make wrong guesses because they reason from the positions of the states, not cities.

  • Relative positions of larger areas are compared, not details – hierarchical chunking.

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Which is farther East: San Diego or Reno?

Which is farther North: Seattle or Montreal?

Which is farther West: the Atlantic or the Pacific entrance to the Panama Canal?

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Translating Verbal Descriptions

  • Subjects were asked to read passages, rotate themselves and make judgments:

    • Fastest when making above-below judgments, slower with right-left.

  • Verbal directions (survey or route) are as good as using actual maps.

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Franklin & Tversky’s Study

Some directions are faster to interpret verbally and orient ourselves in than others.

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Overlap of Visual Perception and Visual Imagery

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