representations n.
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  1. Representations

  2. “… vast quantity of on-going research dependent on Rs ... no scientist knows how mental Rs represent.” • Representing is a relation between two things whereby one stands in for other. • The stand-in = R (words + pictures) • Mental Rs - implemented in brain’s neural architecture (no one is quite sure how)

  3. Implementation = inverse of supervenience. Minds supervene on brains, brains implement minds (Dietrich 2007) • [Supervenience = no mental change without physical change] • Duality mental-physical pp. duality subject-object

  4. Pr. I of Cartesian psychology (Pr of R) Mind, cognition, and intelligence are to be explained in terms of R-l states and ways in which such states are manipulated and transformed. (Wheleer 05) Pr. II: Dichotomy S-O Rs and subject–object dichotomy are intimately interconnected. Rs are context independent (Wheeler 05) • Homuncularity is necessary for R.

  5. a R is something that acts as a stand-in in such a system. (Chemero 09, p. 55) • R and decouplability (offline cognition)(Clark): ‘‘capacity to use inner states to guide behavior in absence of environ-al feature [represented]’’ (‘97, p. 144; 08 p. 150)

  6. Contents and vehicles of Rs • Contents (meaning) = semantic value of a R • Contents – determined by object in world, the relation among Rs or both • Vehicles = syntactic structures or physical realization of objects that play role of Rs (carrying a content) (Eliasmith ‘07) • Contents = what Rs are Rs of • Vehicles = Rs themselves (Mandik 2003)

  7. Format of Rs: • Propositional (Fodor, Pylyshyn) • Image (Metzler, Shepard, Kosslyn) (ex: picture, maps) • Analogous (Mandler, Lakoff, Fauconnier) • Function = Carry information • Conceptual level - Symbolical Rs = Static + discrete → Computations

  8. Fodor/Pylyshyn - Correspondence Rs and neural patterns - not univocal (Fodor and Pylyshyn 1988) • Subconceptual “level” (connectionism) - Subsymbolic or distributed Rs - Content depend upon processing network + environment • Neural level = implemen. of conceptual Rs Vs. • Dynamical ST: no Rs/computations

  9. Debates – R on format or content Fodor/Pylyshyn • Compositionality • Productivity • Systematicity Smolensky • Implicit functional compositionality: assure the advantages of a compositional structure to the brain. (‘88)

  10. Dietrich and Markman (2003) • Cognition: Must use discrete Rs • Discrete Rs iff • contains more than one R (discrete and static) • categorize inputs enviroment (has internal states that impose classes of sameness on inputs) → semantic memory • Discrete Rs = contains more than one R, and Rs - bounded and uniquely identifiable (07) • Computationalism vs. dynamical systems approach ↔ difference discrete-continuous Rs

  11. 7 reasons for DiscreteRs – A cognitive system must: • Discriminate amond states in represented world • Acces specific properties of Rs • Combine Rs • Cog systems – combinatorial structure • Functional role among concepts • Have abstractions • Have non-nomic Rs

  12. Image Rs • Shepard and Metzler (1971); Kosslyn and Shwartz (1977); Funt (1980) Vs. • Skeptical (Pylyshyn 1984, 2002) • Numerous people (computational, psychological, and neurological): pictures + words

  13. Verbal description – information: man in chair is close to man with his head open, who is on a couch • Verbally infer that chair is close to couch. • Using pictorial R, however, no inference is necessary: we can just seethat • Finke, Pinker, and Farah (1989): Imagine the letter “Y.” Put a small circle at bottom of it. Add a horizontal line halfway up. Now rotate figure 180 degrees. (Thagard ’05)

  14. Visual Rs - accessible to different kinds of computations than verbal Rs: 1. Inspect 2. Find 3. Zoom 4. Rotate 5. Transform

  15. Kossylyn – Image Rs (IRs) • fMRI Wraga and Kossylyn (2003) “Seeing with mind eyes” + internal Rs → Perception without sensory input Mental imageries – transformation/manipulation 1) Scanning (Subject memorizing landmarks from a map: “faster away targets from initial landmark, longer took subjects to locate them” → IRs are depictive = preserve spatial extend)

  16. 2) Zooming (to see fine detail from an imaged object, subject can zoom it - “farther away the object appears in image, longer it takes to report correct answer”) 3) Rotation (Shepard et all.) (Two multiarmed objects, task being if those objects are same or not → subjects “mentally rotated one object into alignment with other”) Conclusion: Internal processes - analogous to physical processes

  17. Damage to occipital lobe impairs visual imagery. • Measurements of brain activity: people use visual mental imagery to perform tasks, brain areas used in visual perception become active. • Imagery relies on regions of cortex that are spatially organized in ways that correspond to structure of retina, networks of nerve cells that send impulses to brain. (Thagard 05, p. 106)

  18. Areas of brain immediately connected to retina – spatial organization = structurally similar to that of retina • Since these areas preserve some of spatial structure of objects presented to retina, their activation during imagery suggests that imagery involves picturelike Rs, not just verbal descriptions. • Dehaene et al. (‘99) behavioral + brainimaging experiments: mathematical intuition sometimes depends on visual and spatial Rs (Thagard 05)

  19. Pylyshyn: Propositional Rs (PRs) • Tacit knowledge of physical laws and objects: due to previous experience - Less time to rotate a longer distance than a shorter one • This knolwedge - stored in mind as abstract or languagelike form • Today accepted - 2 forms of Rs (Pavio et all “Imagery and verbal processes”, 1971)

  20. Fodor (2008) • Conceptual vs. nonconceptual Rs • Propozitional vs image Rs or • Discursive vs. Iconic (related to ‘pictorial’ and ‘continuous’) • Nature of iconic Rs - not conceptual • a R = compositional iff its syntactic structure + semantic content - determined by syntactic structure and semantic content of its constituent parts (p. 171)

  21. Discursive R • Every sentence = finite arrangement of constituents that are themselves either primitive or complex • Each complex constituent is a finite arrangement of ‘lexical primitives’ (words). • Lexical primitives have their syntactic and semantic properties intrinsically

  22. a R = syntactically compositional iff its syntactic analysis is exhaustively determined by grammar + syntactic analyses of its lexical primitives. • A discursive R = semantically compositional iff its semantic interpretation is exhaustively determined by its syntax + semantic interpretations of its lexical primitives

  23. (1) John loves Mary. (2) (JohnNP) (lovesv) (MaryNP)VP • Syntactic structure = (2), • Semantic interpretation = John loves Mary • The syntax + semantics - determined by: ‘John’ = noun, denotes John ‘loves’ = verb, denotes relation x loves y ‘Mary’ = noun, denotes Mary

  24. Semantic interpretation of a sentence (of any discursive representation) depends on way that properties of its lexical primitives interact with properties of its constituent structure.

  25. Iconic Rs (p. 173) • Picture principle: If P = a picture of X, then parts of P are pictures of parts of X • Pictures differ from sentences: icons don’t have canonical decompositions into parts; all the parts of an icon are ipso facto constituents (ex. Picture of a person) • No canonical decomposition • No constituent structure • Homogeneous (syntactic + semantic)

  26. Discursive Rs: decompose syntactically and semantically heterogeneous constituents) → logical forms • Iconic Rs: no decomposition → no logical forms → iconic symbols can’t represent things vs. discursive symbols can • Ex.: Propositions - distinction between negative-affirmative, quantified; hypothetical; modal • Pictures don’t have truth-conditions!

  27. Binding problem (B) • Visual information may be divided into separate processing streams in retina and LGN, but information streams might be reintegrated at some later stage of processing downstream from visual cortex. (Horst 07, p. 166) • We perceive one object (color, shape, etc.) vs. • Separate Rs in brain of color, form, motion.

  28. „Teoria de integrare a trăsăturii” (Treisman anii ’80 + 90) • Crick and Koch (1990): b. - through a kind of phase locking between the cells in different areas • Not explain why there is an experiential or phenomenological unity associated with phase binding. It provides a possible mechanism for how binding of information in two processing streams is achieved… (Horst 07)

  29. Milner (1974), von der Malsburg (1981), Singer (’90, ’00):“binding-by-synchrony” • Singer (2007):primele experimente • Coordonarea: prin sincronizarea activităţii diferitelor patternuri neuronale (patternurile au aceiaşi fază a oscilaţiilor – frecvenţa fiind de 40 Hz) → o singura R a obiectului • Maimuţele:sincronizarea nu depinde de problema legăturii, ci cel mult de selectivitatea găsirii marginii unui obiect („border-ownership”) (Yi Dong et al., 2008)