Cognitive Science Concepts: Learning and Ambiguity Resolution

1. Revision Lecture Cognitive Science

2. Past papers Past papers Past papers

3. What is the answer to the question? The answer will nearly always involve: “How amazing it is that people so effortlessly, and rapidly, bring to bear a sophisticated repertoire of knowledge and skills. We’ll try to set out what that knowledge is.” Learning concepts and word meanings Disambiguating word meanings Combining word meanings

4. What are these knowledges? • Artifacts versus natural kinds • Essences • Syntax • Goals • Context • Intentions of others • World knowledge

5. Concept learning: Summary The terms concept/conceptual are used in different ways Some uses are highly simplified Concept learning involves wide ranging background knowledge, and may involve qualitative changes and re-organisations Computationally, working out how to bring to bear just the relevant knowledge, quickly, is key

6. Simple associations not enough • Goal direction / determining tendency • Essences for some types of concept (“natural kinds”) • Defining features present early for some concepts (robber) • Characteristic  defining for others (uncle)

7. Strategy for preparation Have some examples ready - some from the lectures eg Gavagai - modified from the lectures - alternative examples you’ve found from reading

8. Winston's arch learner

9. Strategy for exam Relate the examples to the core issues Critically evaluate the examples Weave them into one coherent narrative, rather than just a list of points

10. Learning word meaningsConstraints that might help 1. General expectations 2. Cognitive constraints 3. Language form (syntax) constraints 4. Pragmatic constraints 5. World knowledge

11. Critical evaluation • Which is the most important clue? • How do the constraints differ (eg whole object / taxonomic; calls for precision) • How would they work together? • Is there a precise model that shows they work at all? • Have the experiments got flaws?

12. Reading the original article To critically evaluate it is really useful to read the original articles

13. Ambiguity • Psycholinguistic evidence of multiple access, and early selection in limited situations • Computational models of sense selection processes • Psycholinguistic data on cerebral hemispheres

14. In short, how are lexical ambiguities resolved? Evidence from different kinds of method psycholinguistic, neuro, computational What does each contribute, what are the weaknesses of each? How can we use them to answer the psychological question: how do people do it?

15. Subordinate bias effect • If preceding context biases interpretation towards less frequent sense  Longer gaze duration • If preceding context is neutral  Unbalanced read as quickly as an unambiguous word, and balanced word-forms are read more slowly

16. SBE Roughly: • Less frequent senses take longer to ‘find’ • Most frequent selected in neutral context (but note, gaze duration not direct evidence)

17. SBE – Re-ordered access model • All meanings accessed in any context • In a neutral context the dominant sense is selected  unbalanced word-forms read more quickly • Context biases to subordinate sense, it becomes available at the same time as, and to the same extent as, the dominant sense, which is itself available because of its frequency competition slows reading

18. Strategy – have a model you can describe How does it relate to the evidence? What does it cover, allow for? What does it not manage to allow for?

19. Model to resolve correct meaning 2 Hirst (1987) Polaroid words automatic multiple access Complex system with several parts Word representations - active Blackboard World knowledge store – associative links

20. Vagueness and instantiation Barclay et al. (1974) heavy as a cue for piano or baby Hörmann (1983) how many is a few depends on context Interpretation a dynamic transaction with knowledge of the world

21. Ambiguity and vagueness • Ambiguity • Vagueness and instantiation • The ambiguity-vagueness spectrum

22. Combining concepts • Fuzzy set model • Selective Modification model • Semantic Interaction model • CARIN model • Dual-process model of noun-noun combination • knowledge and pragmatic factors

23. Pragmatics - Relevance Speaker chooses expression that requires least processing effort to convey intended meaning. Consequently, first interpretation recovered (consistent with the belief that the speaker intended it) will be the intended interpretation. If first interpretation not the correct one, then speaker should have chosen a different expression, for example by adding explicit information.

24. Clark and Clark (1979)Denominal verbs - "contextuals" Tom can houdini his way out of almost any scrape Sense can vary infinitely according to the mutual knowledge of the speaker and hearer Any mutually known property of Houdini, if speaker: "... has good reason to believe... that on this occasion the listener can readily compute [the intended meaning] ... uniquely... on the basis of their mutual knowledge..."

25. Pragmatic approaches emphasise cooperative and coordinated activity by both speaker and hearer. • Self-containment approach emphasises NN combination as a problem for the listener. • On pragmatic account, notion of an interpretation in isolation from any context is defective

26. What is the answer to the question? The answer will nearly always involve: “How amazing it is that people so effortlessly, and rapidly, bring to bear a sophisticated repertoire of knowledge and skills. We’ll try to set out what that knowledge is.” Learning concepts and word meanings Disambiguating word meanings Combining word meanings