“…Many theories of behavioural timing assume the existence of a pacemaker-accumulator system (e.g., Allan, 1998;Gibbon et al 1984;Treisman, 1963;Ulrich et al, 2006;Wearden, 1992;Zakay & Block, 1997; for contrasting accounts, see e.g., Machado, 1997;Mauk & Buonomano, 2004;Staddon & Higa, 1999;Wackermann & Ehm, 2006). There are various instantiations of this idea, but the core assumption is that timing is based on a pacemaker which emits pulses; at the start of the to-be-timed interval, a switch closes so that these pulses flow into an accumulator.…”