  This paper presents Wanderer, a model of how autonomous adaptive systems
coordinate internal biological needs with moment-by-moment assessments of the
probabilities of events in the external world. The extent to which Wanderer
moves about or explores its environment reflects the relative activations of
two competing motivational sub-systems: one represents the need to acquire
energy and it excites exploration, and the other represents the need to avoid
predators and it inhibits exploration. The environment contains food,
predators, and neutral stimuli. Wanderer responds to these events in a way that
is adaptive in the short turn, and reassesses the probabilities of these events
so that it can modify its long term behaviour appropriately. When food appears,
Wanderer be-comes satiated and exploration temporarily decreases. When a
predator appears, Wanderer both decreases exploration in the short term, and
becomes more "cautious" about exploring in the future. Wanderer also forms
associations between neutral features and salient ones (food and predators)
when they are present at the same time, and uses these associations to guide
its behaviour.
