The 20-Minute Rule for Great Public Speaking — On Attention Spans and Keeping Focus

Alf Rehn
Alf Rehn
Apr 11, 2016 · 6 min read

There’s an old quote, one attributed to the American businessman Phil Crosby, that goes:

“No one can remember more than three points.”

This short statement makes an excellent point, and does so in language everyone can understand. Because we can’t remember more than three points, not really. The fact is, we often can’t remember even that many. Life is just too busy and too confusing to really focus on much more, so regardless of how many brilliant notions are thrown our way, we subconsciously try to pick out just a few, sometimes just one, to make sense of it all.

This is particularly true when we sit and listen to somebody. As just sitting and listening isn’t particularly natural, we often feel fidgety and unfocused when in an audience, further limiting the number of points we can remember. So we listen, and hook our attention onto just a few key points — hopefully the same ones the speaker intended.

Smart public speakers understand all this innately, and construct their speeches so that key points are clearly signposted and no more numerous than the audience can handle. Many brilliant keynotes focus on just one single central idea, and although you can kick it up to two, three is often one too many. Fledgling speakers are often told to do the same, to just focus on one or two central ideas. And sometimes they do. Often, however, they fail to do so.

This is usually due to fear, more specifically the fear of losing the audience by not having ‘enough’ to keep their attention. Inexperienced speakers are thus very likely to try to insert lots and lots of points into their speeches, believing that they are needed to keep everyone alert and interested. This is a grave mistake indeed.

I can see where the mistake comes from, though. It is true that audience attention spans aren’t necessarily great. In fact, the average attention span among people who listen to speeches is estimated to be somewhere in the 5–1o minute span, and often towards the lower end of this. Thus it’s understandable that an insecure speaker will try to work with this, inserting a key point every five minutes or so to keep the attention of the audience from wavering. Understandable, but very, very wrong.

Great speakers think about this vexing problem in the opposite way. The reason average attention spans are so short is because people often listen to speeches that are scattered and suffer from a sort of arrhythmia. Sure, you can make your speech as skittish as the most skittish person in the audience, but this will make your talk worse and elevate no-one. Instead, consider the following:

Average speakers plan for average attention spans. Great speakers plan for optimal attention spans.

The optimal attention span for an audience, i.e. the attention span that can be comfortably held by an interested human engaged in listening to a speaker, is not five to ten minutes. Instead, it is approximately twenty (20) minutes. In fact it is slightly less, somewhere in the 18-to-20 span, but twenty minutes is a decent and practical rough idea. Some people can hold their attention even longer, but they are outliers. After twenty minutes, no matter how interested we are, our focus is depleted, and will unless corrective action is taken erode steadily until we literally aren’t listening any longer. Now, this does not mean that people will automatically focus for that amount of time. On the contrary, unless carefully guided, people will lose focus after just a few minutes — for instance the aforementioned five.

What separates really great speakers is that they take the promise of the optimal attention span, and design around this. Rather than trying to force in more things (more points, more flash, more chaff, et cetera), they realize that their job is to utilize these twenty minute units in as efficient a way as possible.

Now, a fairly normal speaking slot at a conference is somewhere in the 30–45 minute span. This is not by accident, as this is just the right amount of time for a good speaker to get two strong points across. Shorter than this, and it’s exactly one point.

Have you ever wondered why TED-talks are 18 minutes long? That’s because this is exactly one unit of optimal attention span.

If you’re allotted 40–45 minutes, this means that you can start breaking down this into “attention units”. 45 minutes in effect means two units of twenty minutes each, with five minutes to spare for an intro or outro. Perfect! You can then start to craft your keynote as not one talk, but two connected ones, complete with a powerful transition.

A transition is a signal to the audience that you’ve moved from one part of your talk to another, and needs to establish that the audience can take a breath, let go of their previous focus, and establish a new one. Such transitions needn’t be long, as they exist primarily as a kind of mental pause. My preferred technique is a slightly longer story or joke, one that might not even seem that connected to the whole — you’re trying to get the audience over a lull in focus, not introduce a new key point. I’ve also seen speakers take an actual pause in the middle, which sounds clunky but can be done more deftly than you might realize.

By breaking down your speech to smaller units, about the length of a TED-talk, you can then start to think about how you will deliver your now partly independent key points. Do you want to do a long intro, or jump straight into a problem. Do you want to make both parts of your speech structurally similar, to give them a kind of harmonious rhythm, or do you consciously want to change tack mid-way to give the speech a sense of dynamic energy? I am personally in the latter camp, but have seen great things achieved with almost identical structures in the earlier and the latter part of a speech.

What this 20-minute rule does is that it forces you to take the structure of your talk seriously. Rather than seeing it as a barrage of punchlines, boom-boom-boom, it becomes a crafted whole. Rather than designing for the worst version of the audience, you design it for the best version thereof. It is more challenging, absolutely, but it also forces you to think about excellence and elevating your points, not just surviving five minutes at a time. Note that although I’ve been talking about a structure with two points, this doesn’t mean that the two points cannot be e.g. two perspectives on the same point, sticking to a single key point throughout.

So what if instead of 45 minutes you only have 30? Well, you’re in luck! Now you can choose! You can either do a slow intro, maybe by introducing yourself more in depth, have a strong one unit talk with a strong point, and then do a calm and leisurely outro. Or you can shorten your units to fifteen minutes. Twenty is your max, and it is OK to abbreviate to fit a slot, as long as you’re not just doing it out of fear or skittishness.

If you have an hour, the same logic applies. You can now think about three whole units, or stick to two but have leisurely intros, transitions and outros. The point is not slavish devotion to the units, but to transform your thinking about how one crafts a good speech.

It’s about moving from the self-fulfilling prophecy of short attention spans, to realizing what you can achieve together with an audience.

Great speakers accept this challenge. They do not accept the short attention span of the audience as a necessary, given thing. Instead they look to the key points they wish to make, see to the time the audience can stay focused, and make damn sure that they do the best they can with that. And in the end, the audience rewards them.

The Art of Keynoting

A publication dedicated to the difficult, fine art and…

The Art of Keynoting

A publication dedicated to the difficult, fine art and profession of delivering keynotes and other speeches from stages. Mostly SFW.

Alf Rehn

Written by

Alf Rehn

Professor of management, speaker, writer, and popular culture geek. For more, see

The Art of Keynoting

A publication dedicated to the difficult, fine art and profession of delivering keynotes and other speeches from stages. Mostly SFW.