Representations

• “… vast quantity of on-going research dependent on Rs + on R, no scientist knows how mental Rs represent.”

• Representing - relation two things: one stands in for other. “stand-in” = R (words+pictures)

• Mental Rs - implemented in brain

• Implementation = Inverse of supervenience Minds supervene on brains, brains implement minds (Dietrich 2007)

• [Supervenience = No mental change without physical change]

Wheleer 05:

• Duality mental-physical pp. duality subject-object

• Pr. I of Cartesian psychology (Pr of R): Mind, cognition, and intelligence – explained in Rs (manipulated/transformed)

• Pr. II: Rs and subject–object dichotomy – interconnected

• Rs are context independent

Principle of explanatory disembodiment:

(Cartesian psychology)

• Informational contents carried by bodily sensations + primitive perceptual states - specified in bodily states → Reliable and flexible intelligent action = No agent’s physical embodiment [= off-line cognition]

• Homuncularity is necessary for R

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 realisation of objects that play role of Rs (carrying a content) (Eliasmith ‘07)

• Contents = What Rs are Rs of

• Vehicles = Rs themselves (Mandik 2003)

Format of Rs:

• Propositional (Fodor, Pylyshyn)

• Image (Metzler, Shepard, Kosslyn) (ex: picture, maps)

• Analogous (Mandler, Lakoff, Fauconnier)

• R = Stored information or stands-in for something

• Function = Carry information

• Conceptual level - Symbolical Rs = Static + discrete → Computations

• 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

• Fodor,Pylyshyn: Neural level = Implemen. of conceptual Rs

• Dynamical ST: No Rs/Computations

Debates – R on format or nature

Fodor/Pylyshyn • Compositionality • Productivity • Systematicity

Smolensky (‘88)• Implicit functional compositionality:

assure the advantages of a compositional structure to the brain

Dietrich and Markman ('03)

• Cognition: Must use discrete Rs

• Discrete Rs = A system have discrete Rs iff contains more than one R (discrete and static); + categorize inputs enviroment → 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

7 reasons for Discrete Rs: A cognitive system must:

1. Discriminate among states in represented world

2. Acces specific properties of Rs

3. Combine Rs

4. Cog systems – combinatorial structure

5. Functional role among concepts

6. Have abstractions

7. Have non-nomic Rs

Image Rs

• Shepard and Metzler (1971); Kosslyn and Shwartz (1977)

• Skeptical (Pylyshyn 1984, 2002)

• Numerous computational, psychological, and neurological: pictures + words

→

• 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 see that

Visual Rs - accessible to different kinds of computations than verbal Rs:

1. Inspect2. Find 3. Zoom 4. Rotate5. Transform

• 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)

Kossylyn – Image Rs (IRs)

• fMRI

Wraga and Kossylyn (2003): “MI”, 2 meanings: “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)

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

• Damage to occipital lobe impairs visual imagery.

• fMRI: Use of visual mental imagery - same brain areas in visual perception

• 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)

• Areas of brain immediately connected to retina – spatial organisation = Structurally similar to that of retina

→ Preserve some spatial structure of objects presented to retina, their activation during imagery suggests that imagery involves picture-like Rs

• Behavioral + brain-imaging experts: Mathematical intuition sometimes depends on visual and spatial Rs (Thagard 05)

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 knowledge - stored in mind as abstract or language-like form

• Today accepted - 2 forms of Rs (Pavio et all “Imagery and verbal processes”, 1971)

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)

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

• 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.

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)

• 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

Binding problem (B)

• Visual information - divided into separate processing streams in retina and LGN, but reintegrated later (Horst 07, p. 166)

• We perceive one object (color, shape, etc)

but

• Separate neural areas for color, form, motion.

• „Teoria de integrare a trăsăturii” (Treisman anii ’80 + 90)

• 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