LINGUIST List 15.1321

Mon Apr 26 2004

Review: Cog Sci/Semantics: van der Zee & Slack (2003)

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  1. Thora Tenbrink, Representing Direction in Language and Space

Message 1: Representing Direction in Language and Space

Date: Mon, 26 Apr 2004 14:25:13 -0400 (EDT)
From: Thora Tenbrink <tenbrinkinformatik.uni-bremen.de>
Subject: Representing Direction in Language and Space

EDITOR: van der Zee, Emile; Slack, Jon
TITLE: Representing Direction in Language and Space
PUBLISHER: Oxford University Press
YEAR: 2003
ANNOUNCED IN: http://linguistlist.org/issues/14/14-2433.html


Thora Tenbrink, University of Bremen, Germany

OVERVIEW

This book contains a collection of thirteen carefully revised and
extended papers originating at a workshop on Language and Space at the
University of Lincoln in July 2000.

To begin with, the editors present a comprehensive overview and
summary of the issues and contents of the book under the heading of
''The Representation of Direction in Language and Space''. They start
by motivating the research issue as such, placing it in the wider
research area on representations of space and time. Direction, in this
book, comprises orientation (of an entity, i.e., object or person),
location in a specific area with regard to another entity, and
direction of movement. The introductory chapter sums up various
insights gained from the different contributions, such as the range of
variety in linguistic directional encoding, spatial distinctions
underlying linguistic directional representations (vectors, half-axes,
half-lines, or topological distinctions) and the ensuing different
models that are presented by the authors throughout the book. Among
the broad variety of insightful generalisations proposed in this
introductory chapter is a comprehensive account of the notion of
reference frame, reconciling a number of (seemingly) contradictory
approaches in order to provide a clear basis for the analyses
undertaken in the book.

In Chapter 2, Barbara Landau deals with ''Axes and Direction in
Spatial Language and Spatial Cognition''. Building on empirical
evidence from previous work, she considers how axes are used in
language and cognition (e.g., memory) independent of, but often
together with, direction information. Locations of objects are
represented by imposing an axial structure on a reference
object. Depending on the experimental task, in some cases axial
information is sufficient, while in others, direction plays an
additional role. In language, direction information is always present
when using projective terms (left/right etc.). But directions can be
confused while preserving the basic axial structure. In language,
distance seems less important than in cognition.

Chapter 3, ''Vectors across Spatial Domains: From Place to Size,
Orientation, Shape, and Parts'' by Joost Zwarts, builds upon earlier
work by the author (and others) representing the semantics of place
terms (used for locating one object's position relative to another) by
means of vectors. Zwarts claims that axes play a role not only in the
application of place terms but also of terms of size, orientation,
shape, and parts. Thus, the earlier work is extended from the domain
of place to other domains. Zwarts shows that vectors can be used in a
consistent (or unified) way to represent different kinds of spatial
relations. He suggests that this representation in fact mirrors
concepts of spatial relations underlying spatial language, but
provides no empirical evidence (other than illustrative linguistic
examples) for this claim.

John O'Keefe deals with ''Vector Grammar, Places, and the Functional
Role of the Spatial Prepositions in English'' (Chapter 4). He compares
spatial prepositions with the firing fields of the spatially coded
place cells in the rat hippocampus, updating earlier work with Lynn
Nadel (1978) in which the involvement of the hippocampus in the
construction of a ''Cognitive Map'' is proposed. O'Keefe presents a
computational model employing direction vectors which is based on his
research group's empirical work with rats, and relates it to
intuitions on English prepositions which are partly supported by other
empirical work.

In chapter 5, ''The Unique Vector Constraint: The Impact of Direction
Changes on the Linguistic Segmentation of Motion Events'', J�rgen
Bohnemeyer also employs vectors as primitives for spatial
representation. He proposes the interesting idea that languages may be
universally constrained in that all direction specifications in a
single simple clause must denote the same direction vector. Thus,
''Sally walked north away from her house'' implies that ''north'' is
the same direction as ''away from her house'', while ''Sally walked
away from her house and the north'' indicates two distinct
directions. This hypothesized language universal concerns neither
language nor cognition per se, but rather, the coding possibilities at
the syntax-semantics interface.

Laura Carlson, Terry Regier, and Eric Covey (Chapter 6), in ''Defining
Spatial Relations: Reconciling Axis and Vector Representations'',
address reference frames and spatial templates as underlying
representations for mapping spatial terms onto spatial regions. They
show that the Attentional Vector Sum model (Regier and Carlson, 2001)
is suitable for accounting for various factors influencing spatial
mappings (orientation, location with respect to the shape of the
reference object, distance). The authors propose that axial structures
underlying reference frames can be coordinated with vector
representations in a spatial template. This approach captures both the
directions indicated by projective terms (spatial relations) in terms
of axes in a reference system, and the influence of various geometric
and functional factors on the alignment of reference systems and the
applicability of the relations.

In Chapter 7, ''Places: Points, Planes, Paths, and Portions'', Barbara
Tversky sums up research dealing with information conveyance in
directional descriptions. She provides evidence that, while people
often refer to landmarks, explicit specifications of direction and
distance are dispreferred and usually remain approximate, both in
production and comprehension. Landmarks provide an easy and
straightforward way of communicating beginning and end points of a
path based on the interactants' shared knowledge about the spatial
environment.

Chapter 8 by Pierre Gambarotto and Philippe Muller, ''Ontological
Problems for the Semantics of Spatial Expressions in Natural
Language'', again presents a model for the representation of
direction, this time however not based on vectors but on regions of
space as ontological primitives. The motivation for this approach is
the insight that, from a cognitive point of view, topology is the most
basic aspect of spatial knowledge. In their model, problems associated
with using points, lines or intervals as primitives are
avoided. Mereotopological relations can be represented in a
straightforward way. The authors also show how the representation of
orientation, distance, and motion works in their approach, and how
functional information associated with the semantics of prepositions
is integrated.

Hedda Schmidtke, Ladina Tschander, Carola Eschenbach, and Christopher
Habel (Chapter 9) deal with ''Change of Orientation''. Their axiomatic
approach uses half-lines in a geometric model of direction that is
neutral with respect to distance. Using this approach, they propose an
analysis for the semantics of verbs of change of orientation such as
''abbiegen'' (turn off), comparing them to related verbs of motion and
verbs of orientation and determining patterns of geometric constraints
on the applicability of the terms.

In Chapter 10, Urpo Nikanne describes ''How Finnish Postpositions See
the Axis System''. Finnish makes more distinctions in the application
of spatial terms than English does: thus, static and dynamic
situations are differentiated grammatically. Furthermore, Nikanne
finds that, in Finnish, vertical terms (above/below) can indeed only
be used for vertical relationships, while expressions like in front of
/ behind (which basically express horizontal relationships) can also
be required in certain vertical (or other) situations, namely, when
motion into a vertical (or other) direction is involved. Motion
induces its own reference frame (or rather, a front/back orientation)
that is independent of horizontal or vertical positions (relative to
the earth); the spatial terms that are used in such a situation are
those that also express relative position on a horizontal plane. From
this fact, Nikanne deduces a feature hierarchy for reference frames.

Emile van der Zee and Rik Eshuis (Ch. 11) address ''Directions from
Shape: How Spatial Features Determine Reference Axis Categorization''.
Based on three experiments on Dutch directional nouns employed in
intrinsic reference systems, they present the ''Spatial Feature
Categorization model'' which accounts for spatial features in the
application of reference axes with different kinds of objects. The
objects in the experiments are varied with respect to relative axis
length, relative curvature of the main plane of symmetry, and contour
expansion along a reference object's main axis.

In Chapter 12, ''Memory for Locations Relative to Objects: Axes and
the Categorization of Regions'', Rik Eshuis presents empirical
evidence suggesting that axes are used to carve up space into regions
that are not - as previously suggested - quadrants, but rather,
half-planes. Thus, an object that is located to the left, but not
exactly on the left half-axis of a reference object, is also located
on either the front or the back half-plane with regard to that
reference object. In other words, space is not divided into four
mutually exclusive regions, but into overlapping half-planes,
resulting in the fact that different spatial relations (e.g.,
linguistic expressions) may be suitable for representation (though not
equally likely). This interesting and intuitively appealing idea is
developed in relation to previous findings on spatial templates and
prototype effects of spatial expressions. Eshuis' account is based on
his own non-linguistic experiments and is entirely compatible with
previous evidence from linguistic tasks.

Finally, Kenny Coventry (Ch.13) addresses ''Spatial prepositions,
Spatial Templates, and 'Semantic' vs. 'Pragmatic' Visual
Representations''. He discusses previous work showing that the
employment of spatial prepositions depends - apart from geometric
factors - on a variety of associated factors that differ across terms,
such as 'control' or 'support'. These two kinds of constraints are
related to findings from visual imagery, where 'semantic'
representations account for general visual information while
'pragmatic' representations concern the objects' affordances.

CRITICAL EVALUATION

The book is carefully edited; readability is enhanced by the clear and
concise layout as well as the availability of abstracts for each
chapter. However, the usage of one comprehensive list of literature
references at the end of the book rather than separate lists at the
end of each chapter is a disadvantage for readers of single chapters
who may not have access to the book as a whole.

Altogether, the book offers a wide range of useful and interesting
insights into the research area of spatial language and spatial
cognition. In spite of the fact that the title seems to suggest a
focus on only a specific sub-part of spatial representation, many
articles in the book offer a fairly broad view on related research
issues. Several formal models for spatial representation (with a focus
on direction) are presented that differ in scope and focus but are not
incompatible. Furthermore, the book comprises several review articles
on empirical work that together provide valuable insights into the
field.

The title of the book contains an expression that has a potential for
polysemic interpretation that could have been more directly addressed
and explored. As indicated above, ''direction'' can be understood to
denote (at least) orientation, relative location, and movement,
opening up a wide range of different interpretations that surely carry
various important distinct implications with regard to the spatial
relationships involved. However, in the book the different senses are
not always clearly differentiated (or else it is not clear how they
are viewed to be related); therefore, the scope of the claims and
insights is not in all cases clear, and important aspects might have
been lost. For example, static and dynamic scenarios may well differ
in the application of spatial relations. Distances are implicitly
present in all static situations involving relative location, since
objects in the real world are located at a specific distance from each
other even though this may not always be specified in a
representation. In contrast, movement in a certain direction may
theoretically take place indefinitely, even though in practice usually
a specific (though often unspecified) distance is covered. Thus,
distance could play a different role in the representation of spatial
relations in static versus dynamic situations.

The articles comprise a variety of different languages. As is often
the case in this research field, English is predominantly used as the
starting point for analysis, especially in approaches dealing with the
interplay of language and cognition or with formalizations (Landau,
Zwarts, O'Keefe, Carlson et al., Tversky, Coventry). However, several
articles deal with the semantics of spatial expressions in other
languages (Gambarotto & Muller: French; Schmidtke et al.: German;
Nikanne: Finnish; van der Zee & Eshuis: Dutch; Eshuis: German,
Bohnemeyer: various languages). Since the relationship between
language and spatial cognition is often addressed, it is astonishing
that the cross-linguistic achievements of the Space group of the MPIP
in Nijmegen do not receive much attention throughout the book
(excepting Bohnemeyer who is himself part of a neighboring group of
the MPIP, namely, Event Representation). There, linguistic and
non-linguistic tasks are systematically compared and the underlying
relationships highlighted. A good overview can be found in Levinson
(2003).

In spite of the fair number of psychological/psycholinguistic
contributions in the book, only few articles (e.g., Eshuis, who
presents impressively detailed analyses) describe original empirical
work. Several others review earlier findings, in some cases
reproducing depictions but (naturally) not providing detailed
information regarding experiments described elsewhere (e.g., Landau,
O'Keefe, Carlson et al., Tversky, Coventry). Articles of this kind
risk that some conclusions cannot easily be comprehended without
access to the earlier publications they draw upon, and it is not in
all cases clear what exactly is new about the present contribution, as
compared to the previous ones that serve as sources. However, they
provide good overviews especially for newcomers to the field.With the
more formal approaches, a different (and equally widespread) problem
is that they sometimes do, and sometimes do not draw on empirical
research to motivate the intuitions on spatial language that are
formalized. For instance, whether or not a spatial term is considered
as applicable in a specific spatial situation very much depends on
contextual factors, not all of which can be captured by linguistic
intuitions on the part of the authors.

Altogether, the book provides rich and varied insights into the field
of spatial language and cognition and is highly recommended to all
researchers in the field, including those that aim at integrating
findings from psychology and linguistics into interdisciplinary work
or other fields in Cognitive Science, and also including interested
readers who are yet unfamiliar with current issues in Spatial
Cognition.

REFERENCES

Levinson, Stephen C. 2003. Space in Language and Cognition. Cambridge
University Press.

O'Keefe, J. and Nadel, L. 1978. The hippocampus as a cognitive map.
Oxford: Clarendon Press.

Regier, T. and Carlson, L. 2001. Grounding spatial language in
perception: An empirical and computational investigation. Journal of
Experimental Psychology: General, 130(2), 273-98.

ABOUT THE REVIEWER

Thora Tenbrink is a research assistant in the DFG Collaborative
Research Center SFB/TR8 "Spatial Cognition: Reasoning, Action,
Interaction" (Bremen & Freiburg, Germany). Her dissertation project
deals with the question how objects and events are localised relative
to other objects and events using spatial and temporal expressions in
natural discourse. Previous work has dealt with discourse relations
and information structure, presuppositions and non-temporal
implications of temporal connectives, especially 'before' and
'after'. Her current focus is on empirical research on spatial
reference systems in human- robot interaction.
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