Timing and anticipation: conceptual and methodological approaches.

Anticipation occurs on timescales ranging from milliseconds to hours to days. This paper relates the theoretical and methodological developments in the study of interval timing in the seconds, minutes and hours range to research on the anticipatory activity induced by regularly timed daily meals. Daily food-anticipatory activity (FAA) is entrained by procedures which are formally identical to procedures studied in Pavlovian and operant conditioning except for the long duration of the interval between feeding opportunities. As in FAA, the conditioning procedures induce orderly anticipatory activity in advance of food presentation. During the interval between foods the behaviors that express anticipation change as the interval progresses. Consequently, no single response represents a pure measure of anticipation. The ability to distinguish between properties of general anticipatory timing mechanisms such as the scalar property (Gibbon, 1977) and dynamic properties of specific response output systems has been facilitated by teaching animals to use arbitrary anticipatory responses like bar-pressing to obtain food. Interval timing research highlights the importance of identifying the mechanisms of perception, memory, decision making and motivation that all contribute to food anticipation. We suggest that future work focused on the similarities and differences in the neural bases of FAA and interval timing may be useful in unravelling the mechanisms mediating timing behavior.