Contribute to Ongoing Psyc Commentary on Green
Stevan Harnad
harnad at coglit.soton.ac.uk
Mon Apr 27 09:24:08 EDT 1998
There is lively Commentary on Green's target article appearing
in Psycoloquy, a refereed electronic journal sponsored by the American
psychological Association. Further Commentary is invited.
(All submissions are refereed.)
URLs: US: http://www.princeton.edu/~harnad/psyc.html
UK: http://www.cogsci.soton.ac.uk/psyc
Address for submitting commentaries:
psyc at pucc.princeton.edu
Instructions at bottom of this message, preceded by latest commentary.
Green, CD. Are Connectionist Models Theories of Cognition?
PSYCOLOQUY 9(04) Tuesday 14 April 1998
ftp://ftp.princeton.edu/pub/harnad/Psycoloquy/1998.volume.9/
psyc.98.9.04.connectionist-explanation.1.green
Orbach, J. Do Wires Model Neurons?
PSYCOLOQUY 9(05) Wednesday 15 April 1998
ftp://ftp.princeton.edu/pub/harnad/Psycoloquy/1998.volume.9/
psyc.98.9.05.connectionist-explanation.2.orbach
O'Brien, GJ. The Role of Implementation in Connectionist Explanation.
PSYCOLOQUY 9(06) Sunday 19 April 1998
ftp://ftp.princeton.edu/pub/harnad/Psycoloquy/1998.volume.9/
psyc.98.9.06.connectionist-explanation.3.obrien
Green, CD. Lashley's Lesson Is Not Germane.
Reply to Orbach
PSYCOLOQUY 9(07) Wednesday 22 April 1998
ftp://ftp.princeton.edu/pub/harnad/Psycoloquy/1998.volume.9/
psyc.98.9.07.connectionist-explanation.4.green
Green, CD. Problems with the Implementation Argument.
Reply to O'Brien
PSYCOLOQUY 9(08) Saturday 25 April 1998
ftp://ftp.princeton.edu/pub/harnad/Psycoloquy/1998.volume.9/
psyc.98.9.08.connectionist-explanation.5.green
Young, ME. Are Hypothetical Constructs Preferred Over Intervening
Variables?
PSYCOLOQUY 9(09) Monday 27 April 1998
ftp://ftp.princeton.edu/pub/harnad/Psycoloquy/1998.volume.9/
psyc.98.9.09.connectionist-explanation.6.young
Grainger, J. & Jacobs, AM. Localist Connectionism Fits the Bill
PSYCOLOQUY 9(09) Monday 27 April 1998
ftp://ftp.princeton.edu/pub/harnad/Psycoloquy/1998.volume.9/
psyc.98.9.10.connectionist-explanation.7.grainger
----------
psycoloquy.98.9.10.connectionist-explanation.7.grainger Mon 27 Apr 1998
ISSN 1055-0143 (6 paragraphs, 8 references, 153 lines)
PSYCOLOQUY is sponsored by the American Psychological Association (APA)
Copyright 1998 Jonathan Grainger
LOCALIST CONNECTIONISM FITS THE BILL
Commentary on Green on Connectionist-Explanation
Jonathan Grainger
Centre de Recherche en Psychologie Cognitive, CNRS
Universite de Provence
Aix-en-Provence
France
grainger at newsup.univ-mrs.fr
Arthur M. Jacobs
Dept. of Psychology
Philips University of Marburg,
Marbug, Germany
jacobsa at mailer.uni-marburg.de
ABSTRACT: Green (1998) restates a now standard critique of
connectionist models: they have poor explanatory value as a result
of their opaque functioning. However, this problem only arises in
connectionist models that use distributed hidden unit
representations, and is NOT a feature of localist connectionism.
Indeed, Green's critique reads as an appeal for the development of
localist connectionist models as an excellent starting point for
building a unified theory of human cognition.
1. First, if we agree that theory development in psychological science
is ready for the shift from prequantitative verbal-boxological modeling
toward more formal modeling efforts, then the kinds of questions we
should be asking are: What kind of quantitative modeling is
appropriate? How should we evaluate its appropriateness? In other
words, the verbal theories of human memory discussed by Green (1998)
are not a serious alternative to whatever connectionism might offer.
They are at best a starting point for developing more formal accounts
of human memory. We have recently argued that localist connectionism
provides a promising framework for such an endeavor (Grainger & Jacobs,
1998).
2. Green (1998), as well as many other critics of connectionism,
appears to use the term connectionism as synonymous with trainable
networks with hidden units (often called PDP models, and typically
trained with backpropagation, Rumelhart, Hinton, & Williams, 1986).
Many connectionist models do not include hidden units. Some of these
are trainable (with Hebbian learning, for example), and some are
hardwired (e.g., McClelland & Rumelhart's, 1981, interactive activation
model). We refer to any connectionist model in which all processing
units can be unambiguously assigned a meaningful interpretation as
"localist connectionist." Note that, as in all connectionist models, all
processing units in localist connectionist models are identical; it is
only their position in the network that guarantees their unique
interpretation. The modeler can artificially label each of these units
in order to facilitate interpretation of network activity.
3. Grainger and Jacobs (1998) analyzed the advantages of adopting
a localist connectionist approach as opposed to the currently more
popular PDP approach. Here we will discuss only those points relevant
to the issues raised by Green (1998). Green identifies the close
connection between theoretical and observable entities as a critical
feature of traditional scientific theories. One must be able to link
transparently the theoretical entities of the theory to the observable
entities in the target world in order to achieve explanatory adequacy.
Without examining the extent to which this is fails to be a feature of
PDP models, it should be clear from the above discussion that localist
connectionist models do provide this transparent link. Units in
localist connectionist models do refer to relatively uncontroversial
aspects of the target world. They represent the categories (such as
letters and words) that the brain has learned from repeated exposure to
the environment.
4. As noted by Jacobs, Rey, Ziegler, and Grainger (1998), transparency
will always tend to diminish as models become more complex. Jacobs et
al. conclude, however, that algorithmic models of the localist
connectionist variety may offer the best trade-off between
clarity/transparency and formality/precision. It is the increased level
of precision that allows localist connectionist models to achieve
greater descriptive adequacy (Jacobs & Grainger, 1994) without
sacrificing explanatory adequacy.
5. Apart from greater explanatory and descriptive adequacy, localist
connectionist models offer a simple means of quantifying pre-existing
verbal-boxological models that have already stood the test of extensive
empirical research. Referring to this point, Page and Norris (1998)
speak of a symbiosis between verbal theorizing and quantitative
modeling. Furthermore, the principle of nested modeling has been
readily applied with localist connectionist models. Adopting this
approach facilitates the process of model-to-model comparison.
Models differing by a single feature (e.g., interactivity, Jacobs &
Grainger, 1992), can be compared, and different variants of the model
can compete in strong inference studies (e.g., Dijkstra & van Heuven,
1998).
6. Finally, localist connectionist models, using the same simple
processing units and activation functions, provide a unified
explanation for phenomena observed in the different subdomains of human
cognition. The general principles that govern processing in all
localist models (e.g., similarity based parallel activation, lateral
inhibition) can also be isolated and analyzed in an easily
interpretable manner (see e.g., Grainger & Jacobs, in press). We
therefore conclude that localist connectionism provides an excellent
starting point for the development of a unified theory of human
cognition.
REFERENCES
Dijkstra, T. & van Heuven, W.J.B. (1998). The BIA model and bilingual
word recognition. In J. Grainger & A.M. Jacobs (Eds.), Localist
connectionist approaches to human cognition. Mahwah, NJ.: Erlbaum.
Grainger, J. & Jacobs, A.M. (1998). On localist connectionism and
psychological science. In J. Grainger & A.M. Jacobs (Eds.), Localist
connectionist approaches to human cognition. Mahwah, NJ.: Erlbaum.
Grainger, J. & Jacobs, A.M. (1998). Temporal integration of information
in orthographic priming. Visual Cognition, in press.
Green, CD. (1998) Are Connectionist Models Theories of Cognition?
PSYCOLOQUY 9(4)
ftp://ftp.princeton.edu/pub/harnad/Psycoloquy/1998.volume.9/
psyc.98.9.04.connectionist-explanation.1.green
Jacobs, A.M. & Grainger, J. (1992). Testing a semistochastic variant of
the interactive activation model in different word recognition
experiments. Journal of Experimental Psychology: Human Perception and
Performance, 18, 1174-1188.
Jacobs, A. M., & Grainger, J. (1994). Models of visual word
recognition: Sampling the state of the art. Journal of Experimental
Psychology: Human Perception and Performance, 20, 1311-1334.
Jacobs, A.M., Rey, A., Ziegler, J.C, & Grainger, J. (1998). MROM-P: An
interactive activation, multiple read-out model of orthographic and
phonological processes in visual word recognition. In J. Grainger &
A.M. Jacobs (Eds.), Localist connectionist approaches to human
cognition. Mahwah, NJ.: Erlbaum.
McClelland, J. L. & Rumelhart, D. E. (1981). An interactive activation
model of context effects in letter perception: Part I. An account of
basic findings. Psychological Review, 88, 375-407.
Page, M. & Norris, D. (1998). Modeling immediate serial recall with a
localist implementation of the primacy model. In J. Grainger & A.M.
Jacobs (Eds.), Localist connectionist approaches to human cognition.
Mahwah, NJ.: Erlbaum.
Rumelhart, D.E., Hinton, G.E. & Williams, R.J. (1986). Learning
internal represenatations by error propagation. In D.E. Rumelhart, J.L.
McClelland, & the PDP research group, Parallel distributed processing:
Explorations in the microstructure of cognition (Vol. 1). Cambridge,
MA: Bradford Books.
INSTRUCTIONS FOR PSYCOLOQUY COMMENTATORS
PSYCOLOQUY is a refereed electronic journal (ISSN 1055-0143) sponsored
on an experimental basis by the American Psychological Association
and currently estimated to reach a readership of 50,000. PSYCOLOQUY
publishes brief reports of new ideas and findings on which the author
wishes to solicit rapid peer feedback, international and
interdisciplinary ("Scholarly Skywriting"), in all areas of psychology
and its related fields (biobehavioral science, cognitive science,
neuroscience, social science, etc.). All contributions are refereed.
Accepted PSYCOLOQUY target articles have been judged by 5-8 referees to
be appropriate for Open Peer Commentary, the special service provided
by PSYCOLOQUY to investigators in psychology, neuroscience, behavioral
biology, cognitive sciences and philosophy who wish to solicit multiple
responses from an international group of fellow specialists within and
across these disciplines to a particularly significant and
controversial piece of work.
If you feel that you can contribute substantive criticism,
interpretation, elaboration or pertinent complementary or supplementary
material on a PSYCOLOQUY target article, you are invited to submit a
formal electronic commentary.
1. Before preparing your commentary, please examine recent
numbers of PSYCOLOQUY if not familiar with the journal.
2. Commentaries should preferably be up to ~200 lines (~1800 words)
3. Please provide a title for your commentary. As many
commentators will address the same general topic, your
title should be a distinctive one that reflects the gist
of your specific contribution and is suitable for the
kind of keyword indexing used in modern bibliographic
retrieval systems. Each commentary should also have a brief
(~100 word) abstract
4. All paragraphs should be numbered consecutively. Line length
should not exceed 72 characters. The commentary should begin with
the title, your name and full institutional address (including zip
code) and email address. References must be prepared in accordance
with the examples given in the Instructions. Please read the
sections of the Instruction for Authors concerning style,
preparation and editing.
Target article length should preferably be up to 1200 lines [c. 10,000
words]. All target articles, commentaries and responses must have (1) a
short abstract (up to 200 words for target articles, shorter for
commentaries and responses), (2) an indexable title, (3) the authors'
full name(s) and institutional address(es).
In addition, for target articles only: (4) 6-8 indexable keywords,
(5) a separate statement of the authors' rationale for soliciting
commentary (e.g., why would commentary be useful and of interest to the
field? what kind of commentary do you expect to elicit?) and
(6) a list of potential commentators (with their email addresses).
All paragraphs should be numbered in articles, commentaries and
responses (see format of already published articles in the PSYCOLOQUY
archive; line length should be < 80 characters, no hyphenation).
It is strongly recommended that all figures be designed so as to be
screen-readable ascii. If this is not possible, the provisional
solution is the less desirable hybrid one of submitting them as
postscript files (or in some other universally available format) to be
printed out locally by readers to supplement the screen-readable text
of the article.
PSYCOLOQUY also publishes multiple reviews of books in any of the above
fields; these should normally be the same length as commentaries, but
longer reviews will be considered as well. Book authors should submit a
500-line self-contained Precis of their book, in the format of a target
article; if accepted, this will be published in PSYCOLOQUY together
with a formal Call for Reviews (of the book, not the Precis). The
author's publisher must agree in advance to furnish review copies to the
reviewers selected.
Authors of accepted manuscripts assign to PSYCOLOQUY the right to
publish and distribute their text electronically and to archive and
make it permanently retrievable electronically, but they retain the
copyright, and after it has appeared in PSYCOLOQUY authors may
republish their text in any way they wish -- electronic or print -- as
long as they clearly acknowledge PSYCOLOQUY as its original locus of
publication. However, except in very special cases, agreed upon in
advance, contributions that have already been published or are being
considered for publication elsewhere are not eligible to be considered
for publication in PSYCOLOQUY,
Please submit all material to psyc at pucc.bitnet or psyc at pucc.princeton.edu
URLs for retrieving full texts of target articles:
http://cogsci.soton.ac.uk/psyc
http://www.princeton.edu/~harnad/psyc.html
gopher://gopher.princeton.edu:70/11/.libraries/.pujournals
ftp://ftp.princeton.edu/pub/harnad/Psycoloquy
ftp://cogsci.soton.ac.uk/pub/harnad/Psycoloquy
news:sci.psychology.journals.psycoloquy
Anonymous ftp archive is DIRECTORY pub/harnad/Psycoloquy HOST ftp.princeton.edu
More information about the Connectionists
mailing list