Categories in the Brain Prototypicality, Subcategorization, Thinking Sydney Lamb Rice University lamb@rice.edu

1. Categories in the Brain Prototypicality, Subcategorization, ThinkingSydney Lamb Rice Universitylamb@rice.edu Shanghai International Studies University 5 November 2010 “to know is to categorize” Jeffrey Ellis

2. Topics in this presentation Phenomena associated with categories Information in the brain Six Hypotheses Explaining the phenomena associated with categories

3. Topics Phenomena associated with categories Information in the brain Six Hypotheses Explaining the phenomena associated with categories

4. Phenomena associated with categories No small set of defining features (with rare exceptions) Fuzzy boundaries Prototypical members and peripheral members Subcategories, and sub-subcategories, in hierarchical chains Categories are in the mind, not in the real world Categories and their memberships vary from one language/culture system to another Categories influence thinking, in both appropriate and inappropriate ways

5. Phenomena associated with categories: 1 No small set of defining features (with rare exceptions) The feature-attribute model fails Works for some mathematical objects, but doesn’t apply to the way people’s cognitive systems apprehend most things Example: CUP

6. Phenomena associated with categories: 2 No small set of defining features (with rare exceptions) Fuzzy boundaries Example: VEHICLE Car, truck, bus Airplane? Boat? Toy car, model airplane? Raft? Roller skate? Snowboard?

7. Fuzzy Categories No fixed boundaries Membership comes in degrees Prototypical Less prototypical Peripheral Metaphorical The property of fuzziness relates closely to the phenomenon of prototypicality

8. Phenomena associated with categories: 3 No small set of defining features (with rare exceptions) Fuzzy boundaries Prototypical members and peripheral members Prototypical CAR, TRUCK, BUS Peripheral: AIRPLANE, TOY CAR, RAFT, ROLLER SKATE, etc. Varying degrees of peripherality

9. Prototypicality phenomena The category BIRD Some members are prototypical ROBIN, SPARROW Others are peripheral EMU, PENGUIN The categoryVEHICLE Prototypical: CAR, TRUCK, BUS Peripheral: ROLLER SKATE, HANG GLIDER

10. Phenomena associated with categories: 4 No small set of defining features (with rare exceptions) Fuzzy boundaries Prototypical members and peripheral members Subcategories, and sub-subcategories, in hierarchical chains ANIMAL – MAMMAL – CARNIVORE – CANINE – DOG –TERRIER – JACK RUSSELL TERRIER – EDDIE Each subcategory has the properties of the category plus additional properties Smallest subcategory has the most properties

11. Phenomena associated with categories: 5 No small set of defining features (with rare exceptions) Fuzzy boundaries Prototypical members and peripheral members Subcategories, and sub-subcategories, in hierarchical chains Categories are in the mind, not in the real world In the world, everything is unique lacks clear boundaries changes from day to day (even moment to moment) Whorf: “kaleidoscopic flux”

12. Phenomena associated with categories: 6 No small set of defining features (with rare exceptions) Fuzzy boundaries Prototypical members and peripheral members Subcategories, and sub-subcategories, in hierarchical chains Categories are in the mind, not in the real world Categories and their memberships vary from one language/culture system to another English: French: bell cloche (of a church) clochette (on a cow) sonnette (of a door) grelot (of a sleigh) timbre (on a desk) glas (to announce a death)

13. Phenomena associated with categories - 7 No small set of defining features (with rare exceptions) Fuzzy boundaries Prototypical members and peripheral members Subcategories, and sub-subcategories, in hierarchical chains Categories are in the mind, not in the real world Categories and their memberships vary from one language/culture system to another Categories influence thinking, in both appropriate and inappropriate ways (B.L. Whorf)

14. Why? No small set of defining features (with rare exceptions) Fuzzy boundaries Prototypical members and peripheral members Subcategories, and sub-subcategories, in hierarchical chains Categories are in the mind, not in the real world Categories and their memberships vary from one language/culture system to another Categories influence thinking, in both appropriate and inappropriate ways

15. Why?Answer: Because of the structure of the brain No small set of defining features (with rare exceptions) Fuzzy boundaries Prototypical members and peripheral members Subcategories, and sub-subcategories, in hierarchical chains Categories are in the mind, not in the real world Categories and their memberships vary from one language/culture system to another Categories influence thinking, in both appropriate and inappropriate ways

16. Topics Phenomena associated with categories Information in the brain Six Hypotheses Explaining the phenomena associated with categories

17. How to explain? We have to examine how our information about categories is represented in the brain The brain is where our linguistic and cultural knowledge is represented This recommendation is in line with a suggestion first made to linguists by Norman Geschwind in 1964 Geschwind: a great neurologist Said that linguists should consider brain struc\ture

18. Sources of information about the brain Aphasiology Research findings during a century-and-a-half Brain imaging Neuroanatomy Other research in neuroscience E.g., Mountcastle, Perceptual Neuroscience (1998)

19. Some things that are now well established The brain is a network Composed, ultimately, of neurons Neurons are interconnected Axons (with branches) Dendrites (with branches) Activity travels along neural pathways Cortical neurons are clustered in columns Columns come in different sizes The smallest: minicolumn – 70-110 neurons Each minicolumn acts as a unit When it becomes active all its neurons are active Locations of various kinds of “information” Visual, auditory, tactile, motor, …

20. Deductions from known facts Everything represented in the brain has the form of a network (the “human information system”) Therefore a person’s linguistic and conceptual system is a network (part of the information system) Every lexeme and every concept is a sub-network Term: functional web(Pulvermüller 2002)

21. Concepts and percepts: Cortical representation Percept: one sensory modality Locations are known Auditory: temporal lobe Visual: occipital lobe Somatosensory: parietal lobe Concept: more than one sensory modality Higher level Angular gyrus, (?)temporal lobe, (?)SMG

22. Example: The concept DOG We know what a dog looks like Visual information, in occipital lobe We know what its bark sounds like Auditory information, in temporal lobe We know what its fur feels like Somatosensory information, in parietal lobe All of the above.. constitute perceptual information are subwebs with many nodes each have to be interconnected into a larger web along with further web structure for conceptual information

23. Topics Phenomena associated with categories Information in the brain Six Hypotheses Explaining the phenomena associated with categories

24. Topic 3 • Six Hypotheses • Functional webs • Cortical Columns • Nodal specificity • Adjacency • Extrapolation to humans • And to linguistic and conceptual structure • Hierarchy in functional webs • Cardinal nodes

25. Hypothesis I: Functional Webs A concept is represented as a functional web Spread over a wide area of cortex Includes perceptual information As well as specifically conceptual information For nominal concepts, mainly in Angular gyrus (?) For some, middle temporal gyrus (?) For some, supramarginal gyrus

26. Building a model of a functional web:First steps Each node in this diagram represents the cardinal node* of a subweb of properties For example C T M V *to be defined in a moment! C – Conceptual M – Motor T – Tactile V – Visual

27. Add phonological recognition For example, FORK Labels for Properties: C – Conceptual M – Motor P – Phonological image T – Tactile V – Visual C T M P V These are all cardinal nodes – each is supported by a subweb The phonological image of the spoken form [fork] (in Wernicke’s area)

28. Add node in primary auditory area For example, FORK Labels for Properties: C – Conceptual M – Motor P – Phonological image PA – Primary Auditory T – Tactile V – Visual C T M P PA V Primary Auditory: the cortical structures in the primary auditory cortex that are activated when the ears receive the vibrations of the spoken form [fork]

29. Add node for phonological production For example, FORK Labels for Properties: C – Conceptual M – Motor P – Phonological image PA – Primary Auditory PP – Phonological Production T – Tactile V – Visual C T M P PP V PA Arcuate fasciculus

30. Part of the functional web for FORK(showing cardinal nodesonly) Each node shown here is the cardinal node of a subweb T M C For example, the cardinal node of the visual subweb PP P V PA

31. An activated functional web(with two subwebs partly shown) T C PP PR PA V M C – Cardinal concept node M – Memories PA – Primary auditory PP – Phonological production PR – Phonological recognition T – Tactile V – Visual Visual features

32. Ignition of a functional web from visual input T C PR Art PA V M

33. Ignition of a functional web from visual input T C PR Art PA V M

34. Ignition of a functional web from visual input T C PR Art PA V M

35. Ignition of a functional web from visual input T C PR Art PA V M

36. Ignition of a functional web from visual input T C PR Art PA V M

37. Ignition of a functional web from visual input T C PR Art PA V M

38. Ignition of a functional web from visual input T C PR Art PA V M

39. Ignition of a functional web from visual input T C PR Art PA V M

40. Ignition of a functional web from visual input T C PR Art PA V M

41. Ignition of a functional web from visual input T C PR Art PA V M

42. Ignition of a functional web from visual input T C PR Art PA V M

43. Ignition of a functional web from visual input T C PR Art PA V M

44. Ignition of a functional web from visual input T C PR Art PA V M

45. Ignition of a functional web from visual input T C PR Art PA V M

46. Speaking as a response to ignition of a web T C PR Art PA V M

47. Speaking as a response to ignition of a web T C PR Art PA V M

48. Speaking as a response to ignition of a web T C PR Art PA V M From here (via subcortical structures) to the muscles that control the organs of articulation

49. An MEG study from Max Planck Institute Levelt, Praamstra, Meyer, Helenius & Salmelin, J.Cog.Neuroscience 1998

50. Hypothesis II: Nodes as Cortical Columns Information is represented in the cortex in the form of functional webs (Hypothesis I) A functional web is a network within the cortical network as a whole consisting of nodes and their interconnections connections represented in graphs as lines Nodes are implemented as cortical columns The interconnections are represented by inter-columnar neural connections and synapses Axonal fibers Dendritic fibers