ABSTRACT
Time and its effects have been particularly sticky problems in the history of behavioral analysis. As any visitor to a zoo probably knows, animals are quite good at anticipating the impending delivery of their food. By some accounts this anticipation is nothing more than the animal's sensitivity to events preceding the food delivery. For example, the animal may smell, hear, or see its caretaker. Alternatively, the animal may be responding to particular levels of ambient light or sound changes associated with the time of day (e.g., of zoo visitors arriving in the area). Finally, its anticipation may be the product of a timing ability, which it uses to predict the occurrence of a regular event.
