Time, space and value.

Abstract

The ability of animals to associate stimuli depends on whether the stimuli are processed by the cognitive system or the affective system. Historically, a distinction was made between "thinking" and "feeling" by the empirical philosophers of the Renaissance. Recent evidence indicates that cognition and affect can be fruitfully applied to animal research. When animals are required to search an external environment for hidden food baits, they display an objective mastery of time and space as if they have acquired a "cognitive map" of the test area. Tests of an animal's ability to span the time between two external events yield intervals which can best be measured in seconds or fractions thereof. When animals consume a food, the affective value of that food is adjusted according to its utility in the internal milieu. If the food is nutritious, visceral feedback raises the preference value of the food. If nausea ensues, the taste becomes disgusting. Tests of an animal's ability to span the time between eating and nausea yield intervals which can best be described in hours or fractions thereof. Cognitive and affective processes are qualitatively distinct and subserved by different neural systems, yet they are both essential for associative learning. We offer a theoretical scheme designed to weld the two components into a single unitary sequence.