Fall 2008
From Moving Articulators to Sound Structure
Freshman Honors Seminar V50.0233
Prof. Adamantios Gafos (ag63@nyu.edu), O.H. Tues 1–2:30 and by appt., 726 Broadway
Major
concepts / distinctions (elaboration / exemplification)
Broad structure of cognition (perception, computation,
action)
Computation ßà
Model = set of rules or equations whose output
or variables correspond to measurable quantities
Nature of computation / model = Symbolic,
Connectionist, Dynamical
Goodness of models: descriptive adequacy, elegance,
predictive power (explanatory adequacy)
Why model behavior?
Allows you to
check that your theory does account for a specific range of data.
You can still
do theory while being explicit.
Due to
complexity of the domain, different pieces of your theory may not be mutually
consistent. An explicit model allows you to check this.
Allows you to
uncover new issues, constraints or predictions imposed by the principles
guiding your model construction. That is, the model becomes a tool for
conducting more empirical work.
Representations = re-present sensory inputs to the
brain or higher mental levels after stimulus life expires
Components of any phonological theory = a theory of
representations + a theory of rules or constraints on the representations (
Phonological representations: flat (SPE-based matrix)
vs. structured (feature geometry)
Phonological representations: static (SPE-based
matrix, autosegments) vs. dynamic (Articulatory Phonology, Browman
& Goldstein 1986)
Static = Symbolic representations (distinctive features, autosegmental
representations, tone, segment-internal structure, skeleton)
Gestural representations (behavioral level, articulatory phonology, time in phonological
representations)
Auditory representations (neural level, Guenther's
DIVA model, nature of speech targets)
Reduction = “explain the facts of phonology in terms
of basic principles of the physical sciences”; (appeal) would end up with fewer
irreducible principles than we thought we ought to have at first sight.
Reduction (Type 1: level of description change as in
“phonology can be reduced to phonetics”; Type 2: level of description not
changed, as in deriving the effects of or replacing one mechanism by an
independently needed mechanism as in “spreading can be reduced to
correspondence”; ex. Type 1: Ohala, J. (1990). There is no interface between phonetics and
phonology: a personal view. Journal of Phonetics, 18, 153-171.
Closure: the higher levels are inextricably linked to
the lower levels
Emergence: higher levels exhibit properties that
cannot be expressed in the language of the lower level (H. Pattee
1973, S. Kauffman 1995). For phonology, see Sapir,
E. 1925. Sound patterns in language. Language 1 (2), 37-51.
Hierarchical organization of cognition (in Type 1
reduction, finding a phonetic basis of a phonological pattern does not preclude
existence of higher-level description and representation)
Symbolic computation = representations + processes
(algorithms)
Relation between discreteness & continuity
Interfaces or
transducers (symbolicßàcontinuous); Fodor
& Pylyshyn 1981, Harnad
1990
Fodor, J. A., & Pylyshyn, Z. W.
(1981). How direct is visual perception? Some
reflections on Gibson’s ‘ecological approach’. Cognition, 9,
139-196.
Harnad,
S. (1990). The symbol grounding problem. Physica D, 42, 335-346.
Dynamic laws
relating order parameters to control parameters
Context effects in cognition
General form of dynamical models
Non-linearity
Fixed points: attractors and repellers
Dynamic stability (preferred modes, patterns are
resistant to noise and exhibit small fluctuations around their mean states)
Change: control parameters can result in qualitative
changes in the dynamics
Performance = Data = F
(Competence) + Noise, F
= lawful link between competence and performance
(‘derivational theory of complexity’: sentences whose derivation involves more computations are more difficult to understand than sentences whose derivation involves fewer computations. Chomsky 1965, Fodor, Bever, & Garrett, 1974. More recent: the grammar is the parser, Phillips 1996; Hawking 2004 on grammatical principles (or as he calls them ‘conventions’) conventionalize domain general (but interacting and competing) performance factors such as efficiency.
Chomsky, N. (1965). Aspects of the theory of syntax.
Fodor, J. A., Bever, T., &
Garrett, M. F. (1974). The psychology of language: An introduction to
psycholinguistics and generative grammar.
Hawkins, J. A. (2004). Efficiency and Complexity in
Grammars.
Top-down vs. bottom-up information processing
Top-down approaches begin with
hypotheses about computational mechanisms (constraint ranking) and then ask how
such mechanisms might operate at the behavioral (vocal tract) / neural level
(cerebellum,
Bottom-up approaches attempt to
explain properties of the system by taking into account known properties of the
behavioral level (sensory and motor principles) or the neural level (cellular
and synaptic components) as accurately as possible