A 18-minutes Wall
Updated: Mar 6, 2022
Audience can get bored when you talk for some time. And this happens earlier than you think (or wish). It is around 18 minutes. Granville mentioned that this time limit was discovered in a US Navy study in the 1970s. Their objective at that time was to best use the time of instructors and students through the Navy’s education system. Interestingly, they found out that the attention span is quite short – just 18 minutes.
In order to break the tedium, Granville then suggested that we should change the medium. The methods include:
Go to Q&A
Use another speaker
Show a tape
Tell a business story a minute
I was fascinated with this 18 minutes Wall. First, when I reflected whether I as a listener lost my attention to a one-way lecture, the limit seemed very true. In general, unless a lecturer was particularly good, I started to day dream in the classroom after some 20 minutes. I thought in more details my experience in the business school. In fact, I normally got myself settled in the first 5 minutes. In the next 10 minutes, I paid a lot of attention. For example, I asked many questions to myself in order to keep myself engaged e.g. ‘How does this relate to that?’, ‘Will this show up in the exam?’, etc. This was particularly the case when the lecturer was lousy. But then after these 15 minutes, there was likely some boring moments and distraction came to my mind e.g. what to eat at lunch. Again, unless the lecturer was real good i.e. did what Granville suggested. I personally experienced the 18 minutes Wall. It is true.
Second, I was fascinated because most of the one-way speaking events in the real world are of more than 18 minutes. And in most of these events there are no medium change like Granville mentioned. The most common one is product briefing. The speaker runs through the product features e.g. screen shots, setup, pricing, procedure for easily over 2 hours. Sometimes, it can last for a day. With the 18 minutes in mind, no wonder such briefings are challenging to the audience. It is kind of sad to realise how little information the audience can acquire despite the time and effort spent by both the audience and the speaker.
Knowing the 18 minutes Wall is important. And of course, it is even more important to circumvent it. On top of Granville’s 5 tips above, I would like to add one more. And it is related to this blog. Yes, it is about asking question. We shall throw questions to the floor regularly. If you ask me, I would say at least 1 question every 3 minutes. Ask, Not Tell!!
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