A person can only hold only “so much” information in working memory

A person can only hold only “so much” information in working memory … here is an anology: There are 5 babies in the bed. Put another one in, and one of the babies in the bed falls out. The bed can only hold “5” babies. Period. This study by Kane et al (2001) published in the Journal of Experimental Psychology further bolsters the theory that our ability to focus and pay attention is largely driven by how many bits of information (“babies”) we can hold in our working memory without losing them in the presence of more bits of information or distractions (“more babies”). Working memory is a skill that is dependent upon timing in the brain. The better the brain’s timing, the better working memory can hold onto the bits of information and use them for the situation (i.e., learning) or problem at hand. Taub et al (2007) have theorized that Interactive Metronome, a patented program that improves timing in the brain, primarily addresses thinking speed and working memory, thereby improving our ability to focus and learn.

Kane, M.J., Blecky, M.K., Conway, A.R.A., and Engle, R.W. (2001) A controlled attention view of working-memory capacity. Journal of Experimental Psychology, 130(2), 169-183.
Taub. G., McGrew, K.S., and Keith, T.Z. (2007). Improvement in interval timing tracking and effects on reading achievement. Psychology in the Schools, 44(8), 849-863.