Stimulus compounding in interval timing: the modality-duration relationship of the anchor durations results in qualitatively different response patterns to the compound cue.

We have previously demonstrated that rats trained on a two-duration peak procedure in which two modal signals (i.e., tone and houselight) predicted probabilistic reinforcement availability at two times (10 s and 20 s) would respond in a scalar manner at a time between the trained durations in response to the simultaneous compound cue (tone + houselight).

Averaging of temporal memories by rats.

Rats were trained on a mixed fixed-interval schedule in which stimulus A (tone or light) indicated food availability after 10 s and stimulus B (the other stimulus) indicated food availability after 20 s. Testing consisted of nonreinforced probe trials in which the stimulus was A, B, or the compound AB. On single-stimulus trials, rats responded with a peak of activity around the programmed reinforced time.