Interval timing: memory, not a clock.

Anticipation of periodic events signalled by a time marker, or interval timing, has been explained by a separate pacemaker-counter clock. However, recent research has added support to an older idea: that memory strength can act as a clock. The way that memory strength decreases with time can be inferred from the properties of habituation, and the underlying process also provides a unified explanation for proportional timing, the Weber-law property and several other properties of interval timing.