Change in the Adult Phonological Processing System by Learning Non-adjacent Phonotactic Constraints from Brief Experience: an experimental and computational study
Recent studies show that the adult phonological processing system
constantly changes as a result of word processing experience; adult
speakers can learn new sound patterns from brief experience processing
words that exhibit the sound patterns, and how they process words changes
as a result of learning. But how malleable is the phonological processing
system and what is the mechanism underlying the adaptation of the system to
recent processing experience? This dissertation presents experiments and
computational models that investigate whether adult speakers can learn
non-adjacent phonotactic constraints, and how their perception and
grammaticality judgment behavior change as a result of learning.
The experiments show that adults can learn phonotactic constraints that are
nonexistent in their language and which restrict co-occurrence of two
non-adjacent phonemes with one intervening phoneme. The results further
document evidence of the malleability of the adult phonological processing
system, and extend the range of learnable sound patterns since non-adjacent
phonological dependencies are assumed to be difficult to learn.
As a result of learning, the speakers judge phonotactically legal novel
words to be more grammatical than phonotactically illegal novel words. They
also perceive the legal ones more quickly and accurately than the illegal
ones. In addition, the experiments show that the effect of learning on
perception is greater when the learned phonotactic constraint restricts
co-occurrence of more confusable phonemes. This subtle effect of learning
on perception is expressed as the Perceptual Facilitation Hypothesis, which
provides a more detailed account of how the phonotactic knowledge functions
in the adult phonological processing system to change its perceptual behavior.
The experimental results are simulated with two computational models that
demonstrate how the adult phonological processing system adapts to recent
experience: how it comes to perceive legal sound sequences better than
illegal ones after repeatedly processing sequences embodying non-adjacent
phonotactic constraints, and how it learns the constraints from observing
the perceptual output and computes the probability of the perceived
phonological structure in judging its grammaticality. The models suggest
possible mechanisms that underlie the adaptation of the adult phonological
processing system and guide the direction of future research by providing
falsifiable predictions.
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