|Title:||U-shaped learning in language acquisition, and restrictions on error correction|
|Authors:||Joseph Stemberger, Barbara Bernhardt|
|Abstract:||Most theories of learning presuppose that a child's system
changes to become more like the adult system. Learning
algorithms are designed to yield that result. However,
children sometimes show u-shaped learning, in which some
aspect of the system becomes less like the adult system than it
had previously been. We explore one instance of u-shaped
learning in the morphology of one English-learning child,
involving (a) the development of word-final clusters,
(b) affix-checking in plurals and past-tense forms, and
(c) double-marking errors in plurals and past-tense forms.
We evaluate several approaches to learning, and conclude that
Tesar and Smolensky's approach cannot account for the
developmental changes, because constraint promotion appears
to be involved. Other approaches (Bernhardt and Stemberger;
Boersma and Hayes; connectionist approaches) fare better.
The data also argue that past tense forms and plurals are
processed within the same language subsystem (module) as
morphologically simple words.