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Visual Imagery

Visual Imagery. Psychology 355: Cognitive Psychology Instructor : John Miyamoto 05/22/2014 : Lecture 08-3.

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Visual Imagery

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  1. Visual Imagery Psychology 355: Cognitive PsychologyInstructor: John Miyamoto05/22/2014: Lecture 08-3 This Powerpoint presentation may contain macros that were used to create the slides. The macros aren’t needed to view the slides. If necessary, you can disable the macros without any change to the presentation.

  2. Outline • Finish preceding lecture: Multimodal representations of objects. • Imagery Debate – Do mental images play a functional rolein human cognition? • Evidence in favor of the functional role of imagery. • Are perception and imagery similar processes? • Behavioral evidence • Neuropsychological evidence Many examples presented today support a general hypothesis: • Brain activity when imagining an object are similar to brain activity when perceiving the object. • Brain activity when categorizing an object is similar to brain activity when interacting with the object. Review – Visual Images, What Are They? Psych 355, Miyamoto, Spr '14

  3. Visual Images – What Are They? • Mental imagery: Experiencing a sensory impression in the absence of sensory input • Visual imagery: “seeing” in the absence of a visual stimulus Table Showing the Pro and Con View of the Functional Importance of Imagery Psych 355, Miyamoto, Spr '14

  4. The Debate Over Mental Imagery Same Slide with Emphasis Rectangles Psych 355, Miyamoto, Spr '14

  5. The Debate Over Mental Imagery Review: Basic Pattern of Argument in the Imagery Debate Psych 355, Miyamoto, Spr '14

  6. Basic Approach to Arguing for the Functional Role of Mental Imagery • Find behavioral or neuropsychological evidence that is ... • easy to explain if we assume that humans possess and use perception-based representations, but ... • hard to explain if we assume that we have only propositional representations. • In general, these arguments are not air tight, but they can be strong and convincing. • Example of Ptolmaic circles in astronomy Review: Shepard's Mental Rotation Study Psych 355, Miyamoto, Spr '14

  7. Shepard's Mental Rotation Experiments • TASK: As quickly as possible, decide whether the two figures have the same shape or different shapes. • Mental rotation experiments: Influential argument for the importance of mental imagery in cognitive processes. Review: Mental Rotation Experiment - Results Psych 355, Miyamoto, Spr '14

  8. Mental Rotation - Results • Response time for "identical" figures is a linear (straight-line) function of the angle of rotation between the figures. • Result is easy to explain if subjects are rotating a mental image. • Result is hard to explain if mental representation is exclusively propositional. 3-D Rotation 2-D Rotation Mean Reaction Time (sec.) Mean Reaction Time (sec.) Angle of Rotation (Degrees) Image Scanning – Kosslyn's Experiment with Island Map Psych 355, Miyamoto, Spr '14

  9. Mental Scanning (Image Scanning) Response Time (sec) Distance (cm) • Figure 10.4: Image scanning is discussed in Goldstein, pp. 273 - 274. • Subjects study the map of the island. Then take it away. • Using only the mental image of the island, imagine a dot moving from one point to another, e.g., from the mountain to the tree. Push a button when you are done. Zooming In or Zooming Out on a Mental Image Psych 355, Miyamoto, Spr '14

  10. Zooming In and Zooming Out on a Mental Image Top: Imagine a rabbit next to an elephant. Yes or No: Does the rabbit have whiskers? Bottom: Imagine a rabbit next to a fly. Yes or No: Does the rabbit have whiskers? Same Slide with Results Added Psych 355, Miyamoto, Spr '14

  11. Zooming In and Zooming Out on a Mental Image Top: Imagine a rabbit next to an elephant. Yes or No: Does the rabbit have whiskers? Bottom: Imagine a rabbit next to a fly. Yes or No: Does the rabbit have whiskers? RT result is hard to explain if you assume that information is retrieved from a semantic network without imagery. RT = 2,020 ms slower RT = 1,870 ms faster Can Imagery Prime Perception Psych 355, Miyamoto, Spr '14

  12. Can Imagery Prime Perception? • Priming – Stimulus A can prime Stimulus B if A is similar to B. Why? Theoretical reason is that A and B activate similar brain areas or processes, so the recent activation by A facilitates the processing of Stimulus B. • Question: Can imagining a visual representation prime the perception of a real visual stimulus? Farah, M. J. (1985). Psychophysical evidence for a shared representational medium for mental images and percepts. Journal of Experimental Psychology: General, 114, 91-103. Farah's Demonstration that Imagery Can Prime Perception Psych 355, Miyamoto, Spr '14

  13. Images Can Act as Primes for Real Visual Displays H H Step (a): Create mental image of H or T while staring at a blank screen. Step (b): After forming a good image, subject presses a button that causes 2 screens to be displayed one after the other. One screen has an H or a T, the other screen is blank. Task: Say whether the letter was on the 1st or the 2nd screen. Results of Farah's Experiment Psych 355, Miyamoto, Spr '14

  14. Farah’s Imagery Priming Paradigm Imagine the letter H inside the rectangle. A sequence of two slides will follow rapidly at the click.You must identify whether the letter is in the 1st or 2nd slide. The stimulus sequence will start on the next key press. Two Stimuli in SlowSuccession (Automatic Advancing of the Slides) Psych 355, Miyamoto, Spr '14

  15. Farah’s Imagery Priming Paradigm Psych 355, Miyamoto, Spr '14

  16. Farah’s Imagery Priming Paradigm H Psych 355, Miyamoto, Spr '14

  17. Was the Letter on the First or Second Slide • Answer: Second slide Another Trial of Farah’s Experiment – Except that the Slide Advance is Faster Psych 355, Miyamoto, Spr '14

  18. Same Experiment - The Next Trial is Faster Imagine the letter Tinside the rectangle. A sequence of two slides will follow rapidly at the click.You must identify whether the letter is in the 1st or 2nd slide. The stimulus sequence will start on the next key press. Two Stimuli in Rapid Succession (Automatic Advancing of the Slides) Psych 355, Miyamoto, Spr '14

  19. Farah’s Imagery Priming Paradigm H Psych 355, Miyamoto, Spr '14

  20. Farah’s Imagery Priming Paradigm Psych 355, Miyamoto, Spr '14

  21. Was the Letter on the First or Second Slide • Answer: First slide Graph of Results of Farah’s Experiment Psych 355, Miyamoto, Spr '14

  22. Results: Images Act as Primes for Real Visual Displays % Correct Detection Results: When mental image is same as target, percent correct is higher. Interpretation: Forming the mental image requires similar brain activity to actual perception. Thereforeforming the mental imageprimes the perception of the target. Conclusion: Imagery Plays a Functional Role in Cognition Psych 355, Miyamoto, Spr '14

  23. Yes – Mental Imagery Plays a Functional Role in Cognition • Lots of evidence – easy to explain if we postulate that people use mental imagery; hard to explain if we claim that people only use propositional representations. • Next Question: How similar are perception and imagery? Overview of Neuropsychological Evidence for Similarity Between Perception & Imagery Psych 355, Miyamoto, Spr '14

  24. Neuropsychological Evidence for Similarity Between Perception & Mental Imagery • Neuropsychological studies show similar patterns for perception or imagining particular types of objects: Faces, scenes, baseballs, etc. • single cell studies • fMRI studies • This evidence for mental imagery is correlational. Do the observed brain patterns result from functionally important processes? • fMRI & single cell studies can't answer this question. • TMS study can demonstrate the causal role of perception and imagery in task performance. Single-Cell Evidence for Similarity Between Perception & Imagery Psych 355, Miyamoto, Spr '14

  25. Single-Cell Studies of Perception & Imagery • Kreiman, Koch & Fried (2000)Single-cell recording inmedial temporal lobeas precursor to surgeryfor epilepsy. • Cell is sensitive to perception andmental image of baseballs, butnot to faces. ImaginetheBaseball PerceivetheBaseball Same Slide with Emphasis on Face Stimuli Psych 355, Miyamoto, Spr '14

  26. Single-Cell Studies of Perception & Imagery • Kreiman, Koch & Fried (2000)Single-cell recording inmedial temporal lobeas precursor to surgeryfor epilepsy. • Cell is sensitive to perception andmental image of baseballs, butnot to faces. PerceivetheFace ImaginetheFace Same Slide with Final Comment re Selectivity of Other Individual Cells Psych 355, Miyamoto, Spr '14

  27. Single-Cell Studies of Perception & Imagery • Kreiman, Koch & Fried (2000)Single-cell recording inmedial temporal lobeas precursor to surgeryfor epilepsy. • Cell is sensitive to perception andmental image of baseballs, butnot to faces. • Also found other cells that were selective for perception & imagery of animals, famous people, and food. Similarity in fMRI Activation During Perception & Imagery Psych 355, Miyamoto, Spr '14

  28. Location of the fusiform face area and parahippocampalgyrus • Graphic from the article: Haynes, J-D., & Rees, G. (2006). Decoding mental states from brain activity in humans. Nature Reviews Neuroscience, 7, 523-534. Parahippocampal place area (PPA) and Fusiform face area (FFA) Diagram of BrainFrom the Side Facing Left Next: fMRI Results for Face & Place Recognition P 355, Miyamoto, Winter '09

  29. fMRI Study of Face and Place Perception/Imagery Subjects either view or imagine a face or place . FFA: Fusiform face area. Specialized for faces. PPA: Parahippocampal place area. Specialized for representing location info. % Signal Change % Signal Change Imagine Perception Next: Look at Just the Upper Left Quadrant of this Graph P 355, Miyamoto, Winter '09

  30. fMRI Study of Face and Place Perception/Imagery Subjects view a face or place . Face stimulus activates FFA; place stimulus does not. FFA: Fusiform face area. Specialized for faces. PPA: Parahippocampal place area. Specialized for representing location info. % Signal Change % Signal Change Imagine Perception Next: Look at Just the Lower Left Quadrant of this Graph P 355, Miyamoto, Winter '09

  31. fMRI Study of Face and Place Perception/Imagery Subjects view a face or place . Place stimulus activates PPA; face stimulus does not. FFA: Fusiform face area. Specialized for faces. PPA: Parahippocampal place area. Specialized for representing location info. % Signal Change % Signal Change Imagine Perception Next: Discuss Results for the Left Half of this Graph P 355, Miyamoto, Winter '09

  32. fMRI Study of Face and Place Perception/Imagery Subjects view a face or place . Face stimulus activates FFA; place stimulus does not. FFA: Fusiform face area. Specialized for faces. PPA: Parahippocampal place area. Specialized for representing location info. % Signal Change % Signal Change Imagine Perception Next: Look at Just the Lower Left Quadrant of this Graph P 355, Miyamoto, Winter '09

  33. fMRI Study of Face and Place Perception/Imagery Subjects view a face or place . Place stimulus activates PPA; face stimulus does not. FFA: Fusiform face area. Specialized for faces. PPA: Parahippocampal place area. Specialized for representing location info. % Signal Change % Signal Change Imagine Perception Next: Discuss Results for the Left Half of this Graph P 355, Miyamoto, Winter '09

  34. fMRI Study of Face and Place Perception/Imagery FFA: Fusiform face area. Specialized for faces. PPA: Parahippocampal place area. Specialized for representing location info. % Signal Change % Signal Change Imagine Perception Face and place stimuli have opposite effects on FFA and PPA. Double dissociationwhen perceiving faces or places. Next: Discuss the Right Half of the Graph P 355, Miyamoto, Winter '09

  35. fMRI Study of Face and Place Perception/Imagery FFA: Fusiform face area. Specialized for faces. PPA: Parahippocampal place area. Specialized for representing location info. % Signal Change % Signal Change Imagine Perception Face and place stimuli have opposite effects on FFA and PPA. Double dissociationwhen imagining faces or places. Do Neurological Impairments Have Equivalent Effects on Perception & Imagination? P 355, Miyamoto, Winter '09

  36. Do Neurological Impairments Have Similar Effects on Perception and Imagery? • Kosslyn's TMS study supports this hypothesis.(Kosslyn’s TMS study will be discussed in section.) • What about permanent neurological impairments due to lesions or strokes? Reminder re Hemispatial Neglect – Transition to HemiSpatial Neglect in Imagery Psych 355, Miyamoto, Spr '14

  37. Hemispatial Neglect (Goldstein calls this "unilateral neglect") Hemispatial Neglect(Unilateral Neglect):A deficit of attention in which one entire half of a visual scene is simply ignored. The cause of unilateral neglect is often a stroke that has interrupted the flow of blood to the right parietal lobe. Figure to the right: Patient’s copy of an image (model) shows systematic deficits. This slide is based on instructional material that was downloaded from the Pearson Publisherswebsite (http://vig.prenhall.com) for Smith & Kosslyn (2006; ISBN 9780131825086). The patient’s copy in the right column neglects the left side of the visual field (opposite to the side of brain damage). Unilateral Neglect in Perception & Images Psych 355, Miyamoto, Spr '14

  38. Left Unilateral Neglect in Perception & Images Bisiach, E., & Luzzatti, C. (1978). Unilateral neglect of representational space. Cortex, 14, 129-133. • Patient with left unilateral neglect was asked to imagine himself standing at one end of the Piazza del Duomo in Milan. • Patient neglected left side of the visual image (in his description) just as he neglected the left side in actual perception. Transition to Question: Are Perception & Imagery Always Similar? Psych 355, Miyamoto, Spr '14

  39. Are Perception & Imagery Always Similar? Due to brain injury, Patient CK has visual agnosia (inability to recognize objects) Figure (a) – incorrect identifications • Dart labeled “feather duster” • Tennis racquet labeled “fencer’s mask” • Asparagus labeled “rose twig with thorns” Figure (b) – drawings from memory • Outline of England • Guitar Figure (b) – If you show CK his drawings at a later time, he cannot recognize (label) what they are. Figure 10.19 (p. 284). (a) Pictures incorrectly labeled by CK who had visual agnosia. (b) Drawings from memory by CK. From study by Behrmann, Moscovitch, & Winocur (1994). (a) (b) Dissociations Between Perception & Imagery Psych 355, Miyamoto, Spr '14

  40. Thursday, May 22, 2014: The Lecture Ended Here Psych 355, Miyamoto, Spr '14

  41. Dissociations Between Imagery & Perception Same Slide without Emphasis Rectangles Psych 355, Miyamoto, Spr '14

  42. Dissociations Between Imagery & Perception Diagram Showing Bottom Up & Top Down Processing of Images Psych 355, Miyamoto, Spr '14

  43. When Are Perception & Imagery Similar? When Are They Different? • Behrmann et al. (1994) point out that perception is more bottom up; Imagery is more top down. Same Slide with Explanation of Behrmann’s Hypothesis Psych 355, Miyamoto, Spr '14

  44. When Are Perception & Imagery Similar? When Are They Different? • Hypothesis: • CK's injury blocks the bottom up input for object perception. • RM injury blocks the top down construction of a mental image. Conclusion - END Psych 355, Miyamoto, Spr '14

  45. Conclusion • Mental manipulation of images is similar to perception of scenes as they undergo the analogous physical alterations. • Perception and imagery engage similar cognitive processes, but they are not perfectly equivalent. END Psych 355, Miyamoto, Spr '14

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