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Perceptual Processes I: Visual and Auditory Recognition

Chapter 2. Perceptual Processes I: Visual and Auditory Recognition. Introduction. visual stimuli previous knowledge perception – pattern recognition – object recognition (1/10 sec) interpretation. Background on Visual Object Recognition. The Visual System

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Perceptual Processes I: Visual and Auditory Recognition

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  1. Chapter 2 Perceptual Processes I: Visual and Auditory Recognition

  2. Introduction • visual stimuli previous knowledge • perception – pattern recognition • – object recognition • (1/10 sec) • interpretation Cognition 7e, Margaret Matlin Chapter 2

  3. Background on Visual Object Recognition • The Visual System • distal stimulus = what is “out there” • proximal stimulus = active retina cells • iconic memory = visual sensory memory • occipital lobe - - primary visual cortex • inferotemporal cortex Cognition 7e, Margaret Matlin Chapter 2

  4. Cerebral Cortex Cognition 7e, Margaret Matlin Chapter 2

  5. Background on Visual Object Recognition • Organization in Visual Perception Gestalt Psychology • figure • ground • ambiguous figure-ground relationship Explanation for figure-ground reversal • adaptation of neurons in visual cortex • people try to solve the visual paradox Cognition 7e, Margaret Matlin Chapter 2

  6. Figure-Ground Relationship Cognition 7e, Margaret Matlin Chapter 2

  7. Background on Visual Object Recognition • Organization in Visual Perception Illusory Contours (subjective contours) • early stages of processing - interpretation • later stages of processing - understanding Cognition 7e, Margaret Matlin Chapter 2

  8. Illusory Contours Cognition 7e, Margaret Matlin Chapter 2

  9. Background on Visual Object Recognition • Theories of Visual Object Recognition Template-Matching Theory • templates • compare stimulus to templates until a match is found • Problems • inflexible • only works for isolated letters, numbers, objects Cognition 7e, Margaret Matlin Chapter 2

  10. Background on Visual Object Recognition • Theories of Visual Object Recognition Feature-Analysis Theory • distinctive features • Eleanor Gibson's research • time to decide if two letters are different (p. 40) • recognizing letters and numbers on envelopes Cognition 7e, Margaret Matlin Chapter 2

  11. Background on Visual Object Recognition • Feature Analysis Theory of Visual Object Recognition • Hubel and Wiesel's research • single-cell recording technique • feature detector “cells” in primary visual cortex – respond to orientation of a visual stimulus Cognition 7e, Margaret Matlin Chapter 2

  12. Feature-Analysis Theory • Problems with Feature-Analysis approach • doesn't account for the relationship between features • doesn't explain recognition of more complex objects Cognition 7e, Margaret Matlin Chapter 2

  13. Background on Visual Object Recognition • Theories of Visual Object Recognition The Recognition-by-Components Theory • Irving Biederman • structural theory • Geons = 3-D shapes • combine geons to form objects • Problem • standard viewpoint vs. different viewpoint • Viewer-centered approach Cognition 7e, Margaret Matlin Chapter 2

  14. Geons Cognition 7e, Margaret Matlin Chapter 2

  15. Top-Down Processing and Visual Object Recognition • The Distinction Between Bottom-Up Processing and Top-Down Processing bottom-up processing top-down processing Top-down processing is especially strong when stimuli are incomplete or ambiguous. Top-down processing is also strong when a stimulus is registered for just a fraction of a second. Combining bottom-up and top-down processing Cognition 7e, Margaret Matlin Chapter 2

  16. Top-Down Processing and Visual Object Recognition • Top-Down Processing and Reading • We don't read letter-by-letter • Analyzing all the individual features in the letters of words would be too much work for the perceptual processes • We can still manage to read a sentence, even if some of the middle letters in a word have been rearranged or … • twlv mr ppl @ prty. Brng2 6pks br. Cognition 7e, Margaret Matlin Chapter 2

  17. Top-Down Processing and Visual Object Recognition • Top-Down Processing and Reading Word superiority effect • Say the letter • O • R • C Cognition 7e, Margaret Matlin Chapter 2

  18. Word superiority effect • Say the RED letter • COW • OAR • BACK • MRD • SEDT Cognition 7e, Margaret Matlin Chapter 2

  19. Top-Down Processing and Visual Object Recognition • Top-Down Processing and Reading • The context of a sentence facilitates the recognition of a word in a sentence • Rueckl and Oden's “bears/beans” study • both bottom-up and top-down processing operate in a coordinated fashion Cognition 7e, Margaret Matlin Chapter 2

  20. Rueckl & Oden’s “Bears/Beans” study Cognition 7e, Margaret Matlin Chapter 2

  21. Top-Down Processing and Visual Object Recognition • In Depth: Overactive Top-Down Processing and Occasional Errors in Object Recognition Change Blindness • fail to detect a change in an object or a scene • Simons and Levin's stranger-and-the-door study • Detecting the difference between two scenes • identify important changes more quickly • more likely to notice an improbable change • do not store a detailed representation of a scene • individual differences Cognition 7e, Margaret Matlin Chapter 2

  22. Top-Down Processing and Visual Object Recognition • In Depth: Overactive Top-Down Processing and Occasional Errors in Object Recognition Inattentional Blindness • fail to notice when an unexpected but completely visible object suddenly appears • Simons and Chabris' basketball study Cognition 7e, Margaret Matlin Chapter 2

  23. Top-Down Processing and Visual Object Recognition • In Depth: Overactive Top-Down Processing and Occasional Errors in Object Recognition Similarities between change blindness and inattentional blindness • both involve top-down processing • when an object appears that is not consistent with their concepts, expectations, and memory, people often fail to recognize this changed object (change blindness) or this new object (inattentional blindness) Cognition 7e, Margaret Matlin Chapter 2

  24. Top-Down Processing and Visual Object Recognition • In Depth: Overactive Top-Down Processing and Occasional Errors in Object Recognition ecological validity visual system is accurate in integrating the gist or general interpretation of a scene focus on what is important Theme 2: Our cognitive errors can often be traced to the use of a rational strategy Cognition 7e, Margaret Matlin Chapter 2

  25. Top-Down Processing and Visual Object Recognition • Ecological validity Why Seeing Is Often Not Believing Boston police officer Kenneth Conley was convicted of perjury and obstruction of justice because he claimed not to have seen a brutal police beating as he chased a murder suspect. The conviction was later overturned, but a new study re-examines his claim. (Handout) Cognition 7e, Margaret Matlin Chapter 2

  26. Face Perception Should be a challenging task Recognizing faces from different angles, in different settings, with different expressions • Recognizing Faces Versus Recognizing Other Objects Face perception as "special" Tanaka and Farah--facial features in context vs. isolation feature identification vs. holistic approach (Gestalt) Cognition 7e, Margaret Matlin Chapter 2

  27. Face Perception • Neuroscience Research on Face Recognition • Prosopagnosia – non-Gestalt • inferotemporal cortex • single-cell recording technique in monkeys • fMRI studies • brain's response to faces in upright and upside-down positions Cognition 7e, Margaret Matlin Chapter 2

  28. Face Perception • Applied Research on Face Recognition cashiers' judgments about ID photos (Kemp and colleagues 1997) security surveillance systems (Burton and colleagues 1999) • familiarity and expertise Cognition 7e, Margaret Matlin Chapter 2

  29. Face Perception • Individual Differences: Face Identification in People with Schizophrenia schizophrenia use of top-down processing in visual perception difficulty perceiving faces • same/different person • same/different emotion Cognition 7e, Margaret Matlin Chapter 2

  30. Speech Perception • Record sound vibrations of someone talking • Translate vibrations into a sequence of sounds that you perceive to be speech • English: 15 sounds/sec = 900 sounds/min • Distinguish the sound pattern of one word from all other irrelevant words • Separate voice of speaker from background noise, including other conversations Cognition 7e, Margaret Matlin Chapter 2

  31. Speech Perception • What is a speech sound? A “phone” is the smallest identifiable unit found in a stream of speech. (e.g., “k” in Kit vs. Skill) • What is a phoneme? The smallest unit of sound that enable meaning contrasts (e.g., “p” and “t” in Spill vs. Still) • How many sounds are there? Cognition 7e, Margaret Matlin Chapter 2

  32. Speech Perception • According to UCLA Phonetic Segment Inventory Database (UPSID), there are 770 sounds in the world’s languages • 47% are unique (i.e., occur in only one language) • Languages average 20 to 27 sounds • Approximately 44 phonemes in English • “Smallest” languages: Rotokas (New Guinea) and Mura (Brazil) with 11 phonemes each. • “Largest” language: !Xu‚) with 141 phonemes. • (a.k.a. !Kung – in parts of Namibia & Botswana) Cognition 7e, Margaret Matlin Chapter 2

  33. Speech Perception • Characteristics of Speech Perception Word Boundaries • Listeners can impose boundaries between words, even when these words are not separated by silence. • Example  Cognition 7e, Margaret Matlin Chapter 2

  34. Speech Perception • Characteristics of Speech Perception Word Boundaries Cognition 7e, Margaret Matlin Chapter 2

  35. Speech Perception • Characteristics of Speech Perception Variability in Phoneme Pronunciation • Phoneme pronunciation varies tremendously • pitch, tone, and rate • lack of precision, • sloppy pronunciation • coarticulation Cognition 7e, Margaret Matlin Chapter 2

  36. Speech Perception • Characteristics of Speech Perception Context and Speech Perception • Context allows listeners to fill in missing sounds. • Phonemic restoration • Warren & Warren's wheel/heel/peel study • Fail to notice mispronunciations • Role of top-down processing Cognition 7e, Margaret Matlin Chapter 2

  37. Speech Perception • Characteristics of Speech Perception • Visual Cues as an Aid to Speech Perception • Visual cues from the speaker’s mouth help us interpret ambiguous sounds. • McGurk effect Cognition 7e, Margaret Matlin Chapter 2

  38. Speech Perception • Theories of Speech Perception The Special Mechanism Approach • speech-is-special approach • humans are born with a specialized device that allows us to decode speech stimuli (phonetic module or speech module) • we process speech sounds more quickly and accurately than other auditory stimuli • categorical perception Cognition 7e, Margaret Matlin Chapter 2

  39. Speech Perception • Theories of Speech Perception The General Mechanism Approaches • humans use the same neural mechanisms to process both speech sounds and nonspeech sounds • speech as learned ability • event-related potential studies • phoneme judgment and visual cues Cognition 7e, Margaret Matlin Chapter 2

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