So there you are working on your next great presentation. The story you have has the power to move mountains. But how do you get your audience to appreciate the story, understand it, internalize it and, hopefully, remember it? A big part of the answer is the rule of four.

Back in a famous 1956 academic paper George Miller posited the idea that short term memory had a capacity of about “seven plus-or-minus two” chunks. That is we can juggle about 7 items of information simultaneously when considering a proposition. From that proposition has come a million (or probably a billion) presentation charts with seven (plus or minus two) bullets in the belief that people would be able to absorb that information and understand the “mountain moving” story.

Four NOT seven
The bad news is that it turns out the magic number seven works if what you are trying to keep in short-term memory is, say, seven single digits – but seven concepts – no way! More recently Professor Nelson Cowan (of the department of Psychological Sciences, at the University of Missouri) has undertaken a range of studies that show the actual number to be four. Charts and diagrams that show a maximum of four comparative concepts work well (e.g. the Gartner magic quadrant, the BCG growth matrix) and people remember them and can apply them. Once you go over that number you have lost them. Actually, if you read David Rock’s excellent book “Your Brain at Work,” you will discover that additional findings show that the number of things we actually REMEMBER … is only one. So why does the magic quadrant or the growth matrix work? We remember them as one entity i.e. a specific diagram.

So take a moment and check any standard decks you use or key presentations that you are preparing. Do you keep to the rule of four? Do you agree with the rule of four? Finally for a great explanation of the application of the rule of four to all of your slide design take a look at Stephen Kosslyn’s book “Clear and to the Point” – in our view a book that is clear and to the point.