Spatial Cognition and Computation 1: 431–445, 1999.
© 2000 Kluwer Academic Publishers. Printed in the Netherlands.
Representing a stable environment by egocentric
updating and invariant representations
RANXIAO FRANCES WANG
Department of Psychology, University of Illinois, Champaign, IL 61820, USA
Abstract. To represent a stable environment despite the experience of changes during self
movements, one can either develop an invariant allocentric representation, or update the
egocentric representations as one moves. Using a disorientation paradigm, three sets of studies
investigated these mechanisms in human navigation and scene recognition. Accuracy in the
conﬁguration of multiple object localization is impaired by disorientation, an effect not due to
artifacts such as memory deterioration over time, intervening physical activities, uncertainty
in self position and orientation, etc., suggesting one can locate objects primarily by updating
their egocentric positions as she or he moves. Disorientation also impaired the judgment of
changes to a scene after viewer movements, suggesting a similar egocentric updating process.
On the contrary, representation of the shape of the surroundings is invariant and persists
through disorientation. The coexistence of multiple mechanisms may increase the ﬂexibility
and robustness of the system.
Key words: egocentric updating, navigation, recognition, reference frame, spatial repre-
One fundamental issue an animal has to deal with is to maintain certain
stability despite the experience of changes caused by self motion. For
example, as one moves the appearance of an object or an array of objects
will change. An object may be near or far, in front or behind, or to the side.
Objects or parts of an object may appear or disappear. Despite these changes,
we nevertheless perceive a stable world, recognize objects and scenes from
various locations, and behave in a coherent manner. What representations and
processes may allow such performance?
There are in principle two classes of solutions to this problem. The ﬁrst
solution is to measure and encode the invariant aspects of the environment
directly (e.g., Gallistel 1990; Gibson 1979; Tolman 1948). For example, one
can encode the location of an object with respect to another object or a set
of other objects, or encode the geometric shape of an object with respect
to its intrinsic axis due to asymmetry, or encode orientation in terms of
north/south/east/west using the global orientation cues. These measurements,
once acquired, are not affected by the exact location and orientation of the