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Using
Geometry To Navigate Is Innate, At Least For Fish. New Study
Examines How Rearing Environment Can Alter Navigation.
August 15, 2007. Source: Blackwell
Publishing Press Room
Many animals, including humans,
frequently face the task of getting from one place to another.
Although many navigational strategies exist, all vertebrate species
readily use geometric cues; things such as walls and corners to
determine direction within an enclosed space. Moreover, some species
such as rats and human children are so influenced by these geometric
cues that they often ignore more reliable features such as a
distinctive object or colored wall.
This surprising reliance on geometry has led researchers to suggest
the existence of a geometric module in the brain. However, since
both humans and laboratory animals typically grow up in environments
not entirely made up of right angles and straight lines, the
prevalent use of geometry could reflect nurture rather than nature.
A new study published in the July issue of Psychological Science, a
journal of the Association for Psychological Science, is the first
attempt to examine whether early exposure to strong geometric cues
influences navigational strategy.
Alisha Brown, a psychology graduate student at the University of
Alberta, raised fish in either a rectangular tank, or a circular
tank free of angular information. Brown and her colleagues later
trained the fish to swim to one particular corner of a
rectangular-shaped test arena with either all white walls (geometric
information only), or one colored wall (featural and geometric
information).
Their results demonstrated that the ability to use geometry to aid
navigation did not depend on exposure to angular geometry during
rearing: in the featureless test arena, fish from both rectangular
and circular rearing tanks used geometry to navigate. However, when
features were present to help navigation, the circle-reared fish
were more likely to depend on the feature even if it meant choosing
a geometrically incorrect corner.
The researchers concluded that the ability to learn about geometry
for navigation seems to be innate, but the use of geometric cues to
navigate is determined by both nature and nurture. When reared in
the absence of rectangular geometric structures, fish show a greater
dependence on features for navigational guidance.
Author Contact: Alisha Brown aabrown@ualberta.ca
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