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[Catherine Harris]

        CONNECTIONIST EXPLORATIONS IN COGNITIVE LINGUISTICS

                      Catherine L. Harris 
     Department of Psychology and Program in Cognitive Science
             University of California, San Diego


Abstract:

Linguists working in the framework of cognitive linguistics have
suggested that connectionist networks may provide a computational
formalism well suited for the implementation of their theories.  The
appeal of these networks include the ability to extract the family
resemblance structure inhering in a set of input patterns, to represent
both rules and exceptions, and to integrate multiple sources of
information in a graded fashion.  The possible matches between
cognitive linguistics and connectionism were explored in an
implementation of the Brugman and Lakoff (1988) analysis of the diverse
meanings of the preposition "over."  Using a gradient-descent learning
procedure, a network was trained to map patterns of the form "trajector
verb (over) landmark" to feature-vectors representing the appropriate
meaning of "over."  Each word was identified as a unique item, but was
not further semantically specified.   The pattern set consisted of a
distribution of form-meanings pairs that was meant to be evocative of
English usage, in that the regularities implicit in the distribution
spanned the spectrum from rules, to partial regularities, to
exceptions.  Under pressure to encode these regularities with limited
resources, the nework used one hidden layer to recode the inputs into a
set of abstract properties.  Several of these categories, such as
dimensionality of the trajector and vertical height of the landmark,
correspond to properties B&L found to be important in determining which
schema a given use of "over" evokes.  This abstract recoding allowed
the network to generalize to patterns outside the training set, to
activate schemas to partial patterns, and to respond sensibly to
"metaphoric" patterns.  Furthermore, a second layer of hidden units
self-organized into clusters which capture some of the qualities of the
radial categories described by B&L.  The paper concludes by describing
the "rule-analogy continuum".  Connectionist models are interesting
systems for cognitive linguistics because they provide a mechanism for
exploiting all points of this continuum.


A short version of this paper will be published in The Proceedings of
the Fifteenth Annual Meeting of the Berkeley Linguistics Society, 1989.

Send requests to:  harris%cogsci.ucsd.edu