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Localization of Function: Example of Face Perception then Gestalt Principles of Perception

Localization of Function: Example of Face Perception then Gestalt Principles of Perception. Psychology 355: Cognitive Psychology Instructor : John Miyamoto 4/8 /2014: Lecture 02-2.

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Localization of Function: Example of Face Perception then Gestalt Principles of Perception

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  1. Localization of Function: Example of Face PerceptionthenGestalt Principles of Perception Psychology 355: Cognitive PsychologyInstructor: John Miyamoto4/8/2014: Lecture 02-2 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 • Localization of function • fMRI Example: Face perception versus place perception • Perceptual heuristics • Gestalt principles of perception Lecture probably ends here Localization of Function Psych 355, Miyamoto, Spr '14

  3. Localization of Function • Specific functions are served by specific areas of the brain • Cognitive functioning breaks down in specific ways when areas of the brain are damaged • Brain imaging can identify areas of the brain that serve specific functions. Diagram of Areas of the Brain Psych 355, Miyamoto, Spr '14

  4. Lobes of the Left Hemisphere Head is facing LEFT Lobes of the Cerebral Cortex (continued) Psych 355, Miyamoto, Spr '14

  5. Next: fMRI Evidence for Brain Areas with Specialized Perceptual Functions O'Craven, K., & Kanwisher, N. (2000). Mental imagery of faces and places activates corresponding stimulus-specific brain regions. Journal of Cognitive Neuroscience, 12, 1013-1023. FFA: Fusiform face area. Specialized for faces.(“ventral occipito-temporal cortex”) PPA: Parahippocampal place area. Specialized for representing location info.(“ventromedial cortical region”) Graphic Showing Location of FFA & PPA Psych 355, Miyamoto, Spr '14

  6. Location of the fusiform face area and parahippocampal gyrus Graphic from http://labnic.unige.ch/nic/htms/fmri.html • 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) Fusiform face area (FFA) Diagram of BrainHead Facing Left fMRI Results for Face & Place Recognition Psych 355, Miyamoto, Spr '14

  7. O’Craven & Kanwisher – Research Hypotheses • Research Goal: To test the claim that the fusiform face area is specialized for face perception. • Prediction: FFA will be activated by face stimuli but not by location stimuli. PPA will be activated by location stimuli but not by face stimuli. Psych 355, Miyamoto, Spr '14

  8. fMRI Study of Face and Place Perception FFA: Fusiform face area. Specialized for faces. PPA: Parahippocampal place area. Specialized for representing location info. % Signal Change % Signal Change Perception Subjects views a face for 4 seconds or a place for 4 seconds. Look at Just the Upper Half of this Graph Psych 355, Miyamoto, Spr '14

  9. fMRI Study of Face and Place Perception FFA: Fusiform face area. Specialized for faces. PPA: Parahippocampal place area. Specialized for representing location info. % Signal Change % Signal Change Perception Subjects views a face or a place . Face stimulus activates FFA; place stimulus does not. Look at Just the Lower Half of this Graph Psych 355, Miyamoto, Spr '14

  10. fMRI Study of Face and Place Perception FFA: Fusiform face area. Specialized for faces. PPA: Parahippocampal place area. Specialized for representing location info. % Signal Change % Signal Change Perception Subjects views a face or a place . Place stimulus activates PPA; face stimulus does not. Point Out that There Is a Double Dissociation Psych 355, Miyamoto, Spr '14

  11. fMRI Study of Face and Place Perception FFA: Fusiform face area. Specialized for faces. PPA: Parahippocampal place area. Specialized for representing location info. % Signal Change % Signal Change Perception Face and place stimuli have opposite effects on FFA and PPA. Double dissociation! Supports claim that FFA serves face perception and PPA serves spatial perception Define Double Dissociation; Discuss Double Dissociation Psych 355, Miyamoto, Spr '14

  12. Double Dissociation in Neuropsychology Suppose you are studying the function of two brain areas, A and B. Physiological results exhibit a double dissociationwith respect to areas A and B if ... • one class of stimuli activates area A and fails to activate area B; • a different class of stimuli activates area B and fails to activate area A. Example: • Viewing faces activates FFA but not PPA; • Viewing places activates PPA but not FFA. Repeat of fMRI Graph with Arrows that Emphasize on Double Dissociation Psych 355, Miyamoto, Spr '14

  13. fMRI Study of Face and Place Perception FFA: Fusiform face area. Specialized for faces. PPA: Parahippocampal place area. Specialized for representing location info. % Signal Change % Signal Change Perception Face and place stimuli have opposite effects on FFA and PPA. Double dissociation! Supports claim that FFA serves face perception and PPA serves spatial perception Controversy over the Specialization of FFA for Faces Psych 355, Miyamoto, Spr '14

  14. Is the FFA Truly Specialized for Faces? • Is FFA activity associated with face perception specifically?Or is it associated with perception in a domain of high expertise and enormous practice? • Gauthier, Skudlarski, Gore & Anderson (2000) Bird experts show increased FFA activity when viewing bird images. Car experts show increased FFA activity when viewing car images. BUT bird and car experts show greatest FFA activity when viewing faces. New Topic: Cognitive Side of Perception & Gestalt Principles Psych 355, Miyamoto, Spr '14

  15. The Cognitive Side of Perception • Bottom Up & Top Down Processing • Inverse Projection Problem • Gestalt Principles of Perception: Some examples • Preliminary topic to object perception Bottom Up & Top Down Processing Psych 355, Miyamoto, Spr '14

  16. Bottom Up and Top Down Processing • Bottom up processing – processing of current stimulation influences what is perceived • Top down processing – person’s background knowledge, learning and expectations influence what is perceived. Bottom up processing is data driven. Top down processing is theory-driven, knowledge-driven, and context-driven. Example of top down processing:Your knowledge of rectilinear solidsinforms your perception. Examples of Top Down and Bottom Up Processing Psych 355, Miyamoto, Spr '14

  17. Examples of Bottom Up Processes • Elementary feature detection, e.g., edge detectors, bar detectors,motion detectors. • The following color perception is bottom up:  Your perception of the red squares is dictated by the stimulus;the perception is not influenced by prior expectations or beliefs. • Similarly, the perceived motion of the blue disk is bottom up. It is controlled by the stimulus,not by your beliefs or expectations. Example of Top Down Processing Psych 355, Miyamoto, Spr '14

  18. Examples of Top Down Processes • When people see a plane crash, at least some witnesses always claim to have seen flames coming from the engines. • (Top-down when claim is false; either top-down or bottom up when it is true.) • Scene understanding involves both top-down and bottom-up processing. Classroom Experiment Psych 355, Miyamoto, Spr '14

  19. Class Experiment: Demonstration of Top Down Processing • Instructor: Divide the classroom into a “left group” and “right group”. • I will show you an image. Briefly write down a label for what you see.E.g., if you see a chair, write down “chair.” • Left half of the room will close their eyes for the first image.Right half of the room will close their eyes for the second image. • Everyone will open their eyes and complete the experiment. Image 1a Psych 355, Miyamoto, Spr '14

  20. Students on Left – Eyes OpenStudents on Right – Eyes Closed Label this image “Image 1a”. Write down a name for what you see. Image 1b Psych 355, Miyamoto, Spr '14

  21. Students on Left – Eyes ClosedStudents on Right – Eyes Open Label this image “Image 1b”. Write down a name for what you see. Image 2 Psych 355, Miyamoto, Spr '14

  22. Everybody’s Eyes Open Label this image “Image 2”. Write down a name for what you see. Collect Results of Class Demo Experiment Psych 355, Miyamoto, Spr '14

  23. Results of Classroom Experiment • We will only collect data for what you saw in Image 2. • People on the LEFT SIDE: Raise your right arm if you wrote down “mouse” or “rat” for Image 2? Raise your left arm if you wrote down “old man” or “man” or “face” for Image 2? • People on the RIGHT SIDE: Raise your right arm if you wrote down “mouse” or “rat” for Image 2? Raise your left arm if you wrote down “old man” or “man” or “face” for Image 2? Show Images 1a, 1b, 2 Psych 355, Miyamoto, Spr '14

  24. . LEFT SIDE saw Image 1a RIGHT SIDE saw Image 1b Top Down Processing:What you see in Image 2 depends in part on what you expect from Image 1. EVERYONE saw Image 2 Summary re Bottom Up & Top Down Processing Psych 355, Miyamoto, Spr '14

  25. Summary re Bottom Up & Top Down Processing • What we see is usually the consequence of both top-down and bottom-up processing. • Remember Helmholtz’s unconscious inference.Top down processes (inferences) fill in information that is not present in the actual stimulus. Inverse Projection Problem Psych 355, Miyamoto, Spr '14

  26. Inverse Projection Problem Inverse Project Problem: For any 2-dimensional image that is projected onto the retina, there are infinitely many different 3-dimensional shapes that could have produced that image. How does the mind decide which shape actually produced the 2-dimensional projected image? Ambiguous Figures: The Ambiguous Box Psych 355, Miyamoto, Spr '14

  27. Example: Ambiguous Images • Do you experience competing interpretations of the image? (I.e., do you experience "Gestalt shifts in perception") Box viewed from above, versus Box viewed from below Young/Old Woman Psych 355, Miyamoto, Spr '14

  28. Example: Ambiguous Images • Do you experience competing interpretations of the image? (a.k.a. "Gestalt shifts in perception") • Young woman, • versus • Old woman mouth mouth Same Image Without the “Mouth” Labels Psych 355, Miyamoto, Spr '14

  29. Example: Ambiguous Images • Do you experience competing interpretations of the image? (a.k.a. "Gestalt shifts in perception") • Young woman, • versus • Old woman Inverse Problem – How Does the Visual System Decide What is 3-D Object? Psych 355, Miyamoto, Spr '14

  30. How Does the Visual System Answer the Question: What Is the Real ObjectThat Produces the Stimulation at the Retina? Basic answers: • The visual system makes a variety of unconscious inferences(Helmoltz's idea). • The visual system uses cues for object relations that usually work (but the system can be fooled by a clever stimulus). What Is a Heuristic? Psych 355, Miyamoto, Spr '14

  31. What is a Heuristic? • A heuristic is a reasoning strategy that is used to solve a problem, make a decision or form a judgment about something. • Perceptual heuristic: A strategy in perceptual information processing that (typically) helps to determine the objective situation that produced the immediate sensations. • Heuristics are typically useful shortcuts. • Heuristics are often adaptive, but they can lead to systematic errors. Craters versus Mounds Psych 355, Miyamoto, Spr '14

  32. Example: Craters or Mounds? "Light Comes From Above" Principle Psych 355, Miyamoto, Spr '14

  33. Example: Craters or Mounds? • People usually see craters on the left image, mounds in the right image. • “Light comes from above” assumption shapes perception 3-D Artwork Psych 355, Miyamoto, Spr '14

  34. Example: Craters or Mounds? • People usually see craters on the left image, mounds in the right image. • “Light comes from above” assumption shapes perception 3-D Artwork Psych 355, Miyamoto, Spr '14

  35. 2-D Artwork That Looks Like 3-D (Sketch) Downloaded from: http://www.dailydot.com/entertainment/lego-chalk-army/ Work is attributed to: http://www.planetstreetpainting.com/ Psych 355, Miyamoto, Spr '14

  36. 2-D Artwork That Looks Like 3-D (Finished Product) Downloaded from: http://www.planetstreetpainting.com/ Psych 355, Miyamoto, Spr '14

  37. The Ames Room • Look at http://www.yorku.ca/eye/Ames%20room.htm • Another example: http://presurfer.blogspot.com/2007_05_01_archive.html Video of the Ames Room Psych 355, Miyamoto, Spr '14

  38. A Video Example of the Ames Room Errol & Ricky: http://www.youtube.com/watch?v=5ic7QGjGEX8 Where We Are Headed in the Perception Topic Psych 355, Miyamoto, Spr '14

  39. Where We Are Headed in the Perception Topic • The point made by the previous slides: Our perceptual system solves the inverse projection problem by applying various perceptual heuristics. • Perceptual heuristics are strategies that provide “best guesses” about the stimulus object. • Next: Gestalt Principles of Perception • Tomorrow: Object Perception • The Recognition-By-Components (RBC) Theory of Object Perception • Many Gestalt principles contribute to the RBC theory. Gestalt Principles of Perception Psych 355, Miyamoto, Spr '14

  40. Will the Lecture End Here? Tuesday, April 08, 2014: The Lecture Ended Here Psych 355, Miyamoto, Spr '14

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