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[Kim Plunkett]

The following technical report is now available. For a copy,
email "psyklone at aau.dk" and include your ordinary mail address.

Kim Plunkett


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           Connectionism and Developmental Theory

                Kim Plunkett and Chris Sinha
               University of Aarhus, Denmark

                          Abstract

The main goal of this paper is to argue for an  ``epigenetic
developmental interpretation'' of connectionist modelling of
human cognitive processes, and to propose that parallel dis-
tributed  processing (PDP) models provide a superior account
of developmental phenomena than that offered by  cognitivist
(symbolic)  computational theories.  After comparing some of
the general characteristics of epigeneticist and cognitivist
theories, we provide a brief overview of the operating prin-
ciples underlying  artificial  neural  networks  (ANNs)  and
their  associated learning procedures.  Four applications of
different PDP architectures to developmental  phenomena  are
described. First, we assess the current status of the debate
between symbolic and connectionist accounts of  the  process
of  English  past  tense  formation.  Second, we introduce a
connectionist model  of  concept  formation  and  vocabulary
growth  and  show  how  it provides an account of aspects of
semantic development in early childhood. Next,  we  take  up
the  problem of compositionality and structure dependency in
connectionist nets, and demonstrate that PDP models  can  be
architecturally  designed  to capture the structural princi-
ples characteristic of human cognition. Finally, we review a
connectionist  model  of  cognitive development which yields
stage-like behavioural properties even though structural and
input assumptions remain constant throughout training. It is
shown how the organisational characteristics  of  the  model
provide a simple but precise account of the equilibration of
the  processes  of  accommodation  and  assimilation.    The
authors  conclude  that  a coherent epigenetic-developmental
interpretation of PDP modelling requires  the  rejection  of
so-called hybrid-architecture theories of human cognition.