Subject: Computer Simulations of Animal Behaviour

            PhD dissertation and simulation software available

DISSERTATION-

Imagine a zebra in the African savannah.  At each moment in time this zebra
has to weigh up alternative courses of action before deciding which one will
be most beneficial.  For instance, it may want to graze because it is short
of food, or it may want to head towards a water hole because it is short of
water, or it may want to remain motionless in order to avoid detection by
the predator lurking nearby.  This is an example of the problem of action
selection: how to choose, at each moment in time, the most appropriate out
of a repertoire of possible actions.

This thesis investigates action selection in a novel way and makes three
main contributions.  Firstly, a description is given of a simulated
environment which is an extensive and detailed simulation of the problem of
action selection for animals.  Secondly, this simulated environment is used
to investigate the adequacy of several theories of action selection (from
both ethology and artificial intelligence) such as the drive model, Lorenz's
psycho-hydraulic model and Maes' spreading activation network - deficiencies
in all of these mechanisms are outlined. Thirdly, a new approach to action
selection is developed which determines the most appropriate action in a
principled way, and which does not suffer from the inherent shortcomings
found in other methods.

A review and bibliography of existing work on action selection is included.


SIMULATION SOFTWARE-

This was written in Suntools rather than Xtools.  It can be run only from
SunView or OpenWindows.  The action selection problem modelled by the
simulated environment comprises 15 different `sub-problems' (getting food,
reproducing, not getting lost, being vigilant for predators, etc), many
internal and external stimuli, and 35 different low-level actions to select
between.