THE ORGANIZATION AND TEMPORAL PROPERTIES OF APPETITIVE BEHAVIOR IN RATS

In the presence and absence of an external interfood clock stimulus (a sequence of flashing lights), rats showed a multimodal behavior patte rn during successive quarters of interfood intervals (IFI) ranging fro m 12 to 192 sec. Responses near the feeder peaked before and just afte r food presentations, whereas locomotion remote from the feeder peaked toward the middle of the IFI. The temporal patterns of nosing in the feeder and remote locomotion were scalar (the time at which a response peaked in the IFI was proportional to the IFI length), whereas the pa tterns of postfood feeder-directed behavior, rearing, and pawgrooming were time bound (peaking at a fixed time after food, regardless of IFI length). Responses varied in their control by the external clock stim ulus. During the last half of the IFI, rats nosed in the feeder more w ith an external clock, but only at intermediate IFIs. During the first quarter of the IFI, rats pawgroomed more with an external clock, but only at the longest IFI. The general sequence of responses during the interfood clock was consistent with the view that food delivery engage s an organized sequence of search states that are expressed through a variety of responses.