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    DJ Bryant:  LEXICAL CONTRIBUTIONS TO SPATIAL REPRESENTATION
                Reply to Brugman on Bryant on Space

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psycoloquy.92.3.51.space.9.bryant          Thursday, September 10, 1992
ISSN 1055-0143                  (7 paragraphs, 6 references, 169 lines)
PSYCOLOQUY is sponsored by the American Psychological Association (APA)
                Copyright 1992 David J. Bryant

                LEXICAL CONTRIBUTIONS TO SPATIAL REPRESENTATION
                Reply to Brugman on Bryant on Space

                David J. Bryant
                Department of Psychology, 125 NI
                Northeastern University
                Boston, MA 02115
                (617) 437-3548
                bryant@northeastern.edu

1.0  LEXICAL DETERMINANTS OF THE DISCOURSE LEVEL

1.1  Brugman (1992) offers a compelling argument why we should attend
to the lexical/grammatical level of language when attempting to explain
spatial representation. I agree with Brugman's general comment that the
lexical/grammatical level is a primary determinant of the discourse
level, and so must be a determinant of the input to the spatial
representation system (SRS). One of the important points Brugman makes
is that the lexical level provides the basic spatial categories needed
to construct a discourse representation. Every language has a
relatively small set of spatial prepositions (Jackendoff & Landau,
1991) that embody a particular type of spatial relation. There is not
much overlap in meaning between prepositions, and so there is little
freedom in choosing lexical items to describe a particular layout of
objects. And because the categories of spatial relations contained at
the lexical level are a small subset of all possible relations, the
lexical level constrains how one can describe space.

1.2  It is interesting to note that spatial prepositions generally do
not specify a frame of reference (see Retz-Schmidt, 1988). One of the
major arguments of the SRS account (Bryant, 1992) was that space is
represented in up to three coordinate systems, the allocentric,
egocentric, and external reference frames. A linguistic description of
an environment must specify a particular frame of reference, which must
be used consistently. However, most spatial prepositions can be used in
all three frames of reference (exceptions seem to be words like
"through" and "inside" that require an object-centered interpretation).
For example, I can say "the computer is BEHIND me," and mean that the
computer occupies a position to my rear. On the other hand, I can
also say "the computer is BEHIND the filing cabinet," and mean that
both the computer and filing cabinet are to my front, but the computer
is further away. The word BEHIND does not specify whether I am using an
egocentric or external frame of reference.

1.3  I entirely agree with Brugman's argument about the importance of
the lexical level in determining the discourse level. Lexical items,
especially spatial prepositions, carry the meaning necessary to
construct propositions that state a spatial relation between two
objects, or between an object and a location in a coordinate framework.
This means that the lexical level does play an important role in
ultimately determining the nature of the input to the SRS.
However, Brugman further suggests that the lexical level serves
directly as input to the SRS. Thus, spatial information carried in
lexical items, especially spatial prepositions, can directly influence
the formation of mental spatial models by the SRS. In the next section
I will examine this hypothesis in terms of the information necessary to
build a spatial model in the SRS.

2.0  DOES THE LEXICAL LEVEL PROVIDE SUFFICIENT INFORMATION FOR THE SRS?

2.1  The SRS must receive information concerning distance and relative
direction to code the location of objects in a coordinate space.
Perceptually, an individual estimates distance and angular displacement
relative to the self and computes allocentric position. Verbal
descriptions can provide information in allocentric as well as
egocentric frames of reference. However, in both cases, a location must
be related to a position in a frame of reference. Lexical entities on
their own, however, don't provide this information.

2.2  Consider the following examples:

        (1) The box is NEAR me
        (2) NEAR me.
        (3) NEAR.

Number 1 is a grammatical sentence that locates a box with respect to
myself. This sentence contains sufficient information to build a simple
spatial model in the SRS. It specifies a frame of reference, the
egocentric frame, by locating the box with respect to me. It specifies
an object that will occupy a location in that frame of reference, and
it specifies a range of possible locations with the preposition NEAR.
Number 2 might also provides sufficient information to form at least
the basis of a spatial model. It specifies a frame of reference
(egocentric) and a range of locations that an object might occupy,
although it does not indicate what the object is. Even though number 2
is not a grammatical sentence, one can imagine a particular space and
set of locations within that space. This could be termed a spatial
model, albeit an extremely impoverished one. Number 3, on the other
hand, cannot serve as the basis for a spatial model. It does not
specify a frame of reference, so the word NEAR does not refer to any
specific spatial situation. The purpose of the SRS is to create
concrete spatial models of particular environments. The word NEAR,
although it has meaning in all three frames of reference, does not
contain enough information to build a spatial model of a specific
environment.

2.3  These examples demonstrate the power as well as the limits of the
lexical level. A single sentence or even a single nongrammatical
sentence fragment can serve as input to the SRS and can begin a mental
spatial model. Thus, if we think of discourse level as a representation
only of connected sentences, my original assumption (Bryant, 1992) is
incorrect. A spatial model in the sense defined by the SRS can be
invoked by a single sentence. Moreover, complete grammatical sentences
don't seem to be necessary to specify the two most important pieces of
information for the SRS - the frame of reference and location in the
coordinate space. It is clear from the examples that Brugman makes a
valid point; it is too simplistic to talk about the discourse level
being the only one that contacts the SRS. Example 2 above suggests
that a small construction that is clearly not discourse can form the
basis of a mental spatial model. This demonstrates the importance of
the lexical level, and of spatial prepositions in particular, because most
of the meaning of the phrase, "NEAR ME," is derived from the category
embodied in the preposition NEAR. However, to form the basis of a
spatial model, the preposition requires one other item (in this case,
ME) to indicate the frame of reference and make the phrase refer to a
specific spatial situation that can be realized in a mental model.

3.0  MUST THE DISCOURSE REPRESENTATION BE PROPOSITIONAL?

3.1  Brugman asks why it was assumed that discourse is represented
propositionally by the language system. She cites a number of theorists
who advance nonpropositional representation of discourse (e.g.,
Lakoff, 1987; Langacker, 1987). Other theorists, however, propose that
discourse is analyzed into a propositional record (e.g., van Dijk &
Kintsch, 1983), and the issue has not been settled. My response to
Brugman's question is to admit that the original assumption is somewhat
arbitrary - none of the studies reviewed in Bryant (1992) provides
conclusive evidence that discourse must be represented in a
propositional format. The basis for the assumption was an effort to
address the longstanding debate in psychology over propositional and
mental-model representations. I would also note that reflecting on
Brugman's comments on this matter has made the merits of
nonpropositional representation clearer. Schematic theories such as
Lakoff's (1987) appear to offer a useful way of dealing with the
problem of underspecification of spatial information in verbal
descriptions. If spatial terms can call up image schemas that describe
geometric properties of the environment, the schemas can be used to
fill in many of the details left out of discourse.

REFERENCES

Brugman, C. (1992). Spatial Cognition: The Perspective from
Theoretical Semantics. PSYCOLOQUY 3(45) space.6.

Bryant, D. J. (1992). A Spatial Representation System in Humans.
PSYCOLOQUY 3(16) space.1.

Jackendoff, R., & Landau, B. (1991). Spatial Language and Spatial
Cognition. In D. J. Napoli & J. A. Kegl (Eds.), Bridges Between
Psychology and Linguistics: A Swarthmore Festschrift for Lila
Gleitman. Hillsdale, NJ: Lawrence Erlbaum Associates.

Lakoff, G. (1987). Women, Fire, and Dangerous Things. Chicago:
University of Chicago Press.

Langacker, R. (1987). Foundations of Cognitive Grammar, vol. 1.
Stanford, CA: Stanford University Press.

Retz-Schmidt, G. (1988). Various Views on Spatial Prepositions.
AI Magazine, 9, 95-105.

Van Dijk, T. A., & Kintsch, W. (1983). Strategies of Discourse
Comprehension. New York: Academic Press.