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Canada (158,223)
Psychology (9,573)
PSYB57H3 (369)
George Cree (102)


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University of Toronto Scarborough
George Cree

PSYB57 – Chapter 4: Representation and Knowledge in Long-term memory 1. Knowledge: info about the world (likely to be true, have a justification for believing) that is stored in memory, from everyday to the formal  interferences during perception! - Essential for the competent function of most mental processes: memory, language, thought, perception and attention - Roles (7): categorization and inference, action, perception and attention, memory, language and thought - Relies on representations!! (lays the groundwork for knowledge) Without knowledge (1) Unable to categorize things: ability to establish that a perceived entity belongs to a particular group of things that share key characteristics (camera – register images but unable to grasp what they mean) - Categorization allows you to draw inferences!! (2) No appropriate action; cannot complete the partial perception. - KNOWLEDGE AFFECTS PERCEPTION (3) No idea where to focus your attention (4) Lose the ability to understand language KNOWLEDGE ENABLES SOPHISTAICATED THOUGHT (Decision making, planning, problem solving, reasoning) 2. Representation: a physical state that stands for an object, event, or concept. (1) Must be intentional – constructed to stand for something else - Evolution entrusted part of the storage of info to unconscious automatic mechanisms in the brain (2) Must carry information – carry info about what it stands for  use info to recognize other things like it - can produce useful inferences about the other ones you encountered 3. 4 Possible Formats for Representation (1) Format (the type of its code) - Elements that make up a rep + how these elements are arranged, relies on characteristics of processes that operate on them to extract info (2) Modality-specific: make use of perceptual/motor systems (3) Amodal: residing outside the perceptual and motor modalities, lack of sensory stimulation (4) Content: info it conveys 4. Modality-specific: make use of perceptual/motor systems An image has 3 ELEMENTS, when taken together DETERMINE CONTENT: (1) Spatiotemporal window: a photograph taken of the scene does not capture everything in that scene, but only that part of it within a “Spatiotemporal window” (2) Stored (storage) units: each individual unit also has a spatiotemporal window. Captures the info within a bounded spatial and temporal region nested within a larger window. (Pixels if the camera is digital, laid out in a grid) (3) Stored information: collective info specifies the content of the image, resides implicitly in the image OCCIPITAL LOBES (V1 area, OCIPPITAL CORTEX): represent visual images, damage in right side  blindness in left visual field! - Pattern of brain activation on brain`s surface = same shape of that of the stimulus - Their spatial layout in the brain is similar to the layout of space in the environment - Mental images found in visual, motor & auditory system, they are interpreted depending on where you focus your attention, interpretation of the object varies. Mental images... – brain images are not as continuous and complete as photographs - Visual attention = responsible for this unevenness - Representations within a processing system that interprets them in specific ways 5. Meaningful entity: an object /event that plays an important role in an organism`s survival and pursuit of goods (frog being able to detect the bug  motor system to catch the bug) - Function of these pop`ns of neurons  detect entities in the world meaningful to frogs - They interpret regions of images as indicating the presence of a particular feature (meaningful sensory aspect of a perceived stimulus)  feature-detecting neurons active  categorize a region of an image as containing a meaningful feature of an object/event Feature detection accomplished NOT BY SINGLE NEURONS, BY POPN OF NEURONS  GRADED response!! (More reliable) NOT an all-or nothing response! As visual signals travel along pathways; from PRIMARY VISUAL CORTEX  OCCIPITAL LOBE  TEMPORAL & PARIETAL LOBES, various types of features are extracted (shape, orientation, color, movement of object)  popns of conjunctive neurons integrate info to establish a feature representation POPNS OF FEATURE-DETECTING NEURONS EXIST FOR ALL MODALITIES, NOT JUST VISION 6. Amodal words & symbols are 2 DIFFERENT THINGS, words stand for amodal symbols that underlie them. Amodal symbols: depend on will & discretion + describe the properties of and relations among meaningful entities in a scene - Lie outside the modalities + with no modality-specific characteristics, usually assumed to reside in knowledge systems  describe contents of a visual states BUT lie outside the visual system! 3 Types of Amodal Systems (1) Frames: a structure that specifies a set of relations that links objects in the environment (2) Semantic networks: rep essentially the same relations and objects in diagram form (3) Property lists: names the characteristics of the entities belonging to a category - Omit the relations btw properties (diff from (1) & (2)!) Properties in Property List Features in Modality-specific Records Symbols that rep properties are amodal Features are modal Captures relatively abstract aspects of an Tend to compare fundamental perceptual object details (edges, color, etc.) Complement images in that they categorize Record points of light or other sensory data regions of an image meaningfully Continue interpretive process Categorize elementary properties of images , in service of identifying meaningful entities 7. Statistical pattern in neural nets: offers greater scope than the amodal system - In TEMPORAL LOBES, become active to stand for an image - Neurons rep the stat patter = conjunctive neurons (1) Elements of a stat pattern can be viewed as neurons/popn of neurons that are on/off – fire/do not fire (2) In an amodal system a single amodal symbol typically reps a category, in a neural net multiple stats pattern can rep the same category Flexibility offered by varying statistical pattern reflects the reality of the world! (Not all cakes are exactly the same) Simulation: stat pattern can reactivate image and feature info even after the original scene is no longer present (the next day your friend reminds you how great the cake was) - Bottom-up processing through a perceptual system produces stat representation, In top-down manner, stat pattern partially reactivated features extracted from the cake  generate mental images, remember past events  re-enacts at least partially the original visual processing 8. Category knowledge: develops from (1) establishing representations of a category`s individual member, (2) integrating those representations (1) All category members become linked by virtue of the common stats units they share (2) Shared units constitute a stat rep of the category, not just of one member  means of retrieving category members from memory , reactivates the image and feature processing associated w/ a category member thereby stimulating it POWER OF CATERGORY KNOWLEDGE – captures and integrates diverse pieces of info about a category (know how to act + can predict what will happen based on experience) - Contains diverse info that goes beyond what is immediately before your eyes  draw many USEFUL INFERENCES + PERFO
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