Ticks per thought or thoughts per tick? A selective review of time perception with hints on future research.

The last decade underwent a revival of interest in the perception of time and duration. The present short essay does not compete with the many other recent reviews and books on this topic. Instead, it is meant to emphasize the notion that humans (and most likely other animals) have at their disposal more than one time measuring device and to propose that they use these devices jointly to appraise the passage of time. One possible consequence of this conjecture is that the same physical duration can be judged differently depending on the reference 'clock' used in any such judgment. As this view has not yet been tested empirically, several experimental manipulations susceptible to directly test it are suggested. Before, are summarized a number of its latent precursors, namely the relativity of perceived duration, current trends in modeling time perception and its neural and pharmacological substrate, the experimental literature supporting the existence of multiple 'clocks' and a selected number of experimental manipulations known to induce time perception illusions which together with many others are putatively accountable in terms of alternative clock readings.