TR: A PDP Framework for Object Permanence Tasks

[Yuko Munakata]

The following Technical Report is available both electronically from
our own FTP server or in hard copy form.  Instructions for obtaining 
copies may be found at the end of this post.

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                    Now You See It, Now You Don't:
              A Gradualistic Framework for Understanding
                   Infants' Successes and Failures
                      in Object Permanence Tasks

                 Yuko Munakata, James L. McClelland,
                 Mark H. Johnson, & Robert S. Siegler
                      Carnegie Mellon University

                    Technical Report PDP.CNS.94.2
                             May, 1994

3.5-month-old infants seem to show an understanding of the concept of
object permanence when tested through looking-time measures.  Why,
then, do infants fail to retrieve hidden objects until 8 months?
Answers to this question, and to questions of infants' successes and
failures in general, depend on one's conception of knowledge
representations.  Within a monolithic approach to object permanence,
means-ends deficits provide the standard answer.  However, the current
experiments with 7-month-old infants indicate that the means-ends
accounts are incomplete.  In the first two studies, infants were
trained to pull a towel or push a button to retrieve a distant toy.
Infants were then tested on trials with an opaque or transparent
screen in front of the toy.  Trials without toys were also included,
and the difference between Toy and No-Toy trials in number of
retrieval responses was used as a measure of toy-guided retrieval.
The means-ends abilities required for toy-guided retrieval in the
Transparent and Opaque conditions were identical, yet toy-guided
retrieval was more frequent in the Transparent condition.  A third
experiment eliminated the possibility that training on the retrieval
of visible toys had led infants to generalize better to the
Transparent condition.  To explain these data, an account of the
object permanence concept as a gradual strengthening of
representations of occluded objects is developed in the form of a
connectionist model.  The simulations demonstrate how a system might
come to form internal representations of occluded objects, how these
representations could be graded and strengthened, and how the
gradedness of representations could differentially impact upon looking
and reaching behaviors.


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Retrieval information for pdp.cns TRs:

unix> ftp 128.2.248.152                 # hydra.psy.cmu.edu
Name: anonymous
Password: <email address>
ftp> cd pub/pdp.cns
ftp> binary
ftp> get pdp.cns.94.2.ps.Z
ftp> quit
unix> zcat pdp.cns.94.2.ps.Z | lpr      # or however you print postscript

NOTE:  

The compressed file is 292340 bytes long.
Uncompressed, the file is 978382 byes long.

The printed version is 43 total pages long.

For those who do not have FTP access, physical copies can be requested from
Barbara Dorney <bd1q+ at andrew.cmu.edu>.