You may have heard that the optimal time chunk for learning is roughly one hour, after which your attention "exponentially" drops, and you may have heard even more precise figures such as 55 minutes. The lowdown is that you waste your time if you try to do one task, that requires sharp attention, for > 1 hr.
But wait. Doesn't this sound like an urban legend? What are the odds that the human attention span exactly equals the time unit we chunk the day into? One hour? Really? Sounds fake.
The origin of the hour as the unit of the day is in the deep past, but one can speculate it it comes out of the duodecimal (base 12) number system that many ancient cultures used. Why base 12? Who knows, but hold your hand palm up and then fold and touch your fingers to your palm. You now have a counting machine - use your thumb to count on your joints and finger tips. Base 12 baby. Could be useful for commerce, counting your flock, etc. Base 12 also makes division easy - dividing by 2,3,4, and 6, all easy. Look at your counting machine again - easy to "chunk" things together in 2's, 3's, 4's, 8's, etc. But I digress.
So the hour is an unit of time defined by ancient number systems; it should have little correlation to human attention span. As it is a "reasonable" unit of time we teach classes for 1 hour. Some education researchers then find that 1 hr is an optimal attention span time. This "finding" conflicts with every single person who went to public school or attended a lecture - close attention for a full hour? Huh?
Apparently the FAA limits lectures to ~ 20 minutes in U.S. flight schools, as they have found that this is the time students can highly absorb information (HT: Philip Greenspun). This is inline with my personal experience - the first 1/3 of a lecture I can really absorb, then things get harder. This 20 minute claim also makes the 1 hr "attention window" make some more sense - if you take engineering you will learn that ~ 3 time constants are sufficient to have some fast ("exponential") decaying process go down to almost nothing (~ 5%). We can have lectures that last for 1 hr, and still get something out of it (not much, but something) - if this was not true we would have dumped the 1 hr lecture long ago. Essentially we are horribly wasting time and being inefficent, not to mention making people uncomfortable and the environment unpleasant, but not to the point that it becomes so blatantly bad that schools actually have to change.
Take away message:
- It seems that 20 minute chunks are ideal for high attention absorption tasks, and by the time you get to an hour you are at the point where it makes no sense to keep going (if high attention is required).
- Schools are both being ineffective in transferring information, and making children uncomfortable, by using 1 hr chunks - if they do not use additional tactics to take "natural" attention span into account. Essentially schools are training many students that learning is a negative experience. Make sure you don't accidentally do this to yourself by using standard "clock time" units instead of "head time" units in planning learning sessions in your schedule.
- The mismatch between "head time" and "clock time" is large enough to cause us problems, but not large enough to force changes in society. Keep this in mind in planning your schedule.
Questions to think about:
- What about "flow", when does this 20 minute rule no longer apply? (hint: think about the "direction" of flow...). In flow situations, what is a good time chunk? Is this completely idiosyncratic?
- How can you use this 20 minute rule to help you learn/engage in your work and life? Can you see any areas where you are trying to push longer, and thereby both waste time (due to inefficient absorption) and implicitly "train yourself" to dislike the task? There may be low hanging fruit here for increasing your efficiency and effectiveness, as well as increase your pleasure in a task (which goes a long way to being good at it).
- 20 minutes may be "optimal" in terms of being highly receptive, but this rule will be both an average and indicates the most receptive time frame. For yourself, and your given task, you may be able to go a bit longer, or must go a bit less. But 1 hr is likely the cutoff beyond which you are completely wasting time. Experiment - 4o minutes might be good for you/your task, etc. - with times between 20 minutes and 1 hr to see what works.
- Why 20 minutes? What are the mechanisms that make 20 minutes a natural unit of time for paying attention?
