Spatial cognition in three dimensions
Abstract
To date, most studies of spatial learning have been conducted in the horizontal plane,
with few addressing the vertical dimension. I aimed to investigate learning of 3-D
locations by wild, free-living hummingbirds and compare them with rats. In my first
experiment, I found that hummingbirds can encode a 3-D rewarded location after a
single visit. Using a one-dimensional array, I then found that the birds more readily
learned a location in a horizontal than in a vertical linear array. However, the ease of
learning was a product not only of the orientation of the array but also of its spacing
scale. By the end of training, hummingbirds visited the central rewarded flower and
the two adjacent flowers more than they visited the distal flowers for all arrays.
However, when the array was horizontal and the flowers spaced 30 cm apart, they
learned the absolute location of the rewarded flower. In a diagonal array birds
learned the 2-D reward location but they chose at random when tested on a vertically
or horizontally oriented array. However, when birds trained in the diagonal array
were tested on a 180° rotated diagonal array they chose the flower with the same
horizontal component as the rewarded flower rather than with the flower with the
same vertical component. Finally in order to compare the spatial learning of animals
that move in volumes with those who move in two dimensions I trained
hummingbirds and rats to a rewarded location in a cubic maze. Although both
hummingbirds and rats learned a 3-D location within a cubic maze, hummingbirds
appeared to learn the rewarded location as a 3-D coordinate while rats seemed to
learn the vertical and horizontal component of the 3-D location independently. In
addition, hummingbirds were more accurate in the vertical and rats in the horizontal,
which is consistent with their type of locomotion. More experiments in volumetric, terrestrial and climbing animals are needed in order to determine whether the
contrasting search strategies and learning accuracies constitute adaptations to
particular spatial niches.
Type
Thesis, PhD Doctor of Philosophy
Collections
Items in the St Andrews Research Repository are protected by copyright, with all rights reserved, unless otherwise indicated.