Implicit Working Memory
If you look at a conventional mechanical metronome you will notice that when the slider is pushed all the way up to end of the wand, the metronome clicks at 40 beats per minute. I have not seen antique metronomes but the electronic metronome I have also stops at 40 and it is clear that somebody at some point decided that 40 bpm was pretty much the limit of what metronome manufacturing was required to offer the musical public. The way simple devices are constructed for human use often reveal important clues about how the mind works and that is the case here. Metronome design reflects specific limitations that people have in their hearing, in their feeling of rhythm, and more generally in the way their stream of consciousness flows. In this article I try and give some insight into what 40 bpm means for human memory and why the number is 40 and not as small as 10 or as large as 100. I will begin with some remarks on perceptual organization because this is what metronomes are built to regulate.
