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Abstract:
Hierarchical theories of human spatial memory propose that places are grouped together in regions that are represented at a higher level in a graph-like representation of
space. In this project we study the dynamics of the formation of spatial memory, with
special focus on the information about regions. At witch particular stage of memory
formation is regional information used in spatial memory, compared to more detailed
information like the exact positions of places within these regions. We hypothesize that
regional information originates very early in the formation of spatial memory. To investigate
this assumption we have created a virtual environment containing 16 objects
of 4 distinct categories (animals, cars,
owers and buildings). The objects were placed
on a regular 4x4 grid within the environment. We created 2 experimental conditions
that diered in the arrangement of the objects. While objects of the same semantic
category were neighboring each other in the regionalized condition, the object positions
were scrambled in the unregionalized condition. Subjects were randomly assigned
to one of the two environments. In successive trials the subjects had to nd objects
in the environment. They were instructed to approach the target-object as directly as
possible. We recorded subjects trajectories and calculated an overshoot-value for all of
the 32 successive trials. The overshoot-value was dened as the quotient of the traveled
distance and the distance of the shortest possible path. By analyzing the overshootvalues
as a function of the trials for both the experimental groups we monitored spatial
learning. Results indicate faster learning in the regionalized environment as compared
to the unregionalized environment. These results support our hypothesis that regional
information is used in spatial memory very early. These regions allow to reduce the
search area in spatial search tasks; as soon as a given landmark can be assigned to a
certain environmental area, one can limit the search for this landmark to this area.
