Modelling the perceptual development of phonological contrasts with OT and the GLA

1. Modelling the perceptual developmentof phonological contrasts with OT and the GLA Paola Escudero p.r.escudero@reading.ac.uk Paul Boersma paul.boersma@hum.uva.nl Utrecht Institute of Linguistics May 14 2001

2. Introduction • The Language Acquisition task • The task in Phonological Acquisition • Mapping from acoustic input to discrete categories • E.g. • Overview of the talk • /I/ vs. /i/ in two English varieties • Modelling perception and its acquisition • Comparison with real listeners

3. Elspeth’s production environment(Scottish English)

4. Liz’s production environment(Southern English)

5. Elspeth’s and Liz’saverage production environments

6. Do Elspeth and Liz perceive [349 Hz, 74 ms] as “ship” or as “sheep”?

7. Why does perception have to depend on the production environment? • Answer: to optimise perception, the listener has to minimise the probability of perceptual confusion • The optimal perception strategy, therefore, is: likelihood maximisation, i.e. choose the most likely produced category, given a certain F1 & duration

8. Maximum likelihood strategy

9. The knowledge underlying Elspeth’s and Liz’ optimal perception

10. Initial stage of babies Elspeth and Liz

11. How is the knowledge acquired? • Answer: Little Elspeth learns by applying the GLA whenever she makes a categorisation error

12. How little Elspeth learns to perceive“ship” and “sheep” reliably (1)

13. How little Elspeth learns to perceive“ship” and “sheep” reliably (2)

14. How little Elspeth learns to perceive“ship” and “sheep” reliably (3)

15. How little Elspeth learns to perceive“ship” and “sheep” reliably (4)

16. How little Elspeth learns to perceive“ship” and “sheep” reliably (5)

17. How little Elspeth learns to perceive“ship” and “sheep” reliably (6)

18. How little Liz learns to perceive “ship” and “sheep” reliably (1)

19. How little Liz learns to perceive “ship” and “sheep” reliably (2)

20. How little Liz learns to perceive “ship” and “sheep” reliably (3)

21. How little Liz learns to perceive “ship” and “sheep” reliably (4)

22. How little Liz learns to perceive “ship” and “sheep” reliably (5)

23. How little Liz learns to perceive “ship” and “sheep” reliably (6)

24. Real vs. Simulated listeners

25. What about L1-Spanish Isabel, who moves to Scotland and then to Southern England?

26. Isabel’s production environment (Spanish)

27. Isabel’s adult perception (Spanish)

28. Isabel’s new production environment (Scottish English)

29. How Isabel learns to perceive“ship” and “sheep”

30. Isabel’s new production environment (Southern English)

31. How Isabel learns to perceive“ship” and “sheep”

32. Three types of real L2 categorisation Spectral reliance only Cue integration Duration reliance only

33. Summary • For our perception model, we assumed: • Perception is handled by an OT grammar • Its acquisition is handled by the GLA • L2 learners start by copying their L1 grammar • With these assumptions, we can model: • L1 Scottish and Southern English • L2 Scottish and Southern English, partially

34. Conclusion • Cue reliance depends on cue reliability, or a) Differences in the production environment account for differences in perception. b) Changes in the production environment lead to changes in perception. • The functional principle underlying this production-perception dependence is “minimisation of perceptual confusion”. • This functional principle follows from our formal modelling of the perception grammar.

35. Thank you for your attention!