No subject

[Kim Plunkett]

Please note that Jordan Pollack has kindly posted a recently
announced TR on the neuroprose directory under "plunkett.tr9020.ps.Z".
Just to remind you of the contents, the abstract follows:

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           From Rote Learning to System Building:
Acquiring Verb Morphology in Children and Connectionist Nets

                        Kim Plunkett
                    University of Aarhus
                          Denmark

                     Virginia Marchman
              Center for Research in Language
            University of California, San Diego

                          Abstract

The traditional account of the acquisition of  English  verb
morphology  supposes  that  a  dual  mechanism  architecture
underlies the transition from early rote learning  processes
(in  which past tense forms of verbs are correctly produced)
to the systematic treatment of  verbs  (in  which  irregular
verbs  are prone to error). A connectionist account supposes
that this transition can occur in a single mechanism (in the
form  of  a  neural  network) driven by gradual quantitative
changes in the size of the training set to which the network
is  exposed.  In  this  paper,  a  series  of simulations is
reported in which a multi-layered perceptron learns  to  map
verb  stems  to  past  tense forms analogous to the mappings
found in the English past tense  system.  By  expanding  the
training  set in a gradual, incremental fashion and evaluat-
ing network performance on both trained and novel  verbs  at
successive  points in learning, we demonstrate that the net-
work undergoes reorganizations that result in a shift from a
mode  of  rote  learning to a systematic treatment of verbs.
Furthermore, we show that this  reorganizational  transition
is  contingent  upon a critical mass in the training set and
is sensitive to the phonological sub-regularities character-
izing the irregular verbs. The optimal levels of performance
achieved in this series of simulations compared to  previous
work   derives  from  the  incremental  training  procedures
exploited in the current simulations.  The pattern of errors
observed  are  compared  to  those of children acquiring the
English past tense, as well  as  children's  performance  on
experimental studies with nonsense verbs. Incremental learn-
ing procedures are discussed in light of theories of  cogni-
tive  development.   It  is  concluded  that a connectionist
approach offers a viable alternative account of the acquisi-
tion  of English verb morphology, given the current state of
empirical evidence relating to processes of  acquisition  in
young children.