paper available

[Robbie Jacobs]

The following paper is now available via anonymous ftp from the
neuroprose archive.  The paper has been accepted for publication
in the journal "Cognitive Science."  The manuscript is 44 pages.

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   Encoding Shape and Spatial Relations: The Role of Receptive
     Field Size in Coordinating Complementary Representations

   
          Robert A. Jacobs              Stephen M. Kosslyn
       University of Rochester          Harvard University


An effective functional architecture facilitates interactions among
subsystems that are often used together.  Computer simulations showed
that differences in receptive field sizes can promote such organization.
When input was filtered through relatively small nonoverlapping receptive
fields, artificial neural networks learned to categorize shapes relatively
quickly; in contrast, when input was filtered through relatively large
overlapping receptive fields, networks learned to encode specific shape
exemplars or metric spatial relations relatively quickly.  Moreover, when
the receptive field sizes were allowed to adapt during learning, networks
developed smaller receptive fields when they were trained to categorize
shapes or spatial relations, and developed larger receptive fields when
they were trained to encode specific exemplars or metric distances.  In
addition, when pairs of networks were constrained to use input from the
same type of receptive fields, networks learned a task faster when they
were paired with networks that were trained to perform a compatible type
of task.  Finally, using a novel modular architecture, networks were not
pre-assigned a task, but rather competed to perform the different tasks.
Networks with small nonoverlapping receptive fields tended to win the
competition for categorical tasks whereas networks with large overlapping
receptive fields tended to win the competition for exemplar/metric tasks.

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FTP-host:      archive.cis.ohio-state.edu
FTP-filename:  /pub/neuroprose/jacobs.rfield.ps.Z


Robbie Jacobs
robbie at psych.rochester.edu