Enumeration in time is irresistibly event-based.

One of the most fundamental questions that can be asked about any process concerns the underlying units over which it operates. And this is true not just for artificial processes (such as functions in a computer program that only take specific kinds of arguments) but for mental processes. Over what units does the process of enumeration operate? Recent work has demonstrated that in visuospatial arrays, these units are often irresistibly discrete objects. When enumerating the number of discs in a display, for example, observers underestimate to a greater degree when the discs are spatially segmented (e.g., by connecting pairs of discs with lines): you try to enumerate discs, but your mind can't help enumerating dumbbells. This phenomenon has previously been limited to static displays, but of course our experience of the world is inherently dynamic. Is enumeration in time similarly based on discrete events? To find out, we had observers enumerate the number of notes in quick musical sequences. Observers underestimated to a greater degree when the notes were temporally segmented (into discrete musical phrases, based on pitch-range shifts), even while carefully controlling for both duration and the overall range and heterogeneity of pitches. Observers tried to enumerate notes, but their minds couldn't help enumerating musical phrases - since those are the events they experienced. These results thus demonstrate how discrete events are prominent in our mental lives, and how the units that constitute discrete events are not entirely under our conscious, intentional control.