The Magic Number 4?

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Another possible myth of presentation design is that the magic number for retention is:

7 +/- 2

It appears that the actual magical number is closer to 4.

A psychologist by the name of Alan Baddeley dug up the number ofter quote from the research paper by George Miller and actually found that it was a talk from a professional meeting, not research!

Baddeley did his own studies to support the number 4 as the true “magic” number for memory and information processing. However, this has not been studied extensively in medical education, especially with the ideas of organizing and anchoring.

So, for now, we can try to build our presentations around the number 4, but may be able to stretch this much further when other educational principles are applied.


Miller, G. (1956) “The magical number seven plus or minus two: Some limits on our capacity for processing information.” Psychological Review. 63:81-97

Baddeley A. (1994) “The magic number seven: Still magic after all these years?” Psychological Review. 101:353-6

The Truth about Serif vs San Serif Fonts…

I have long wondered about some of the “rules” of presentation design. One of them which I used to mention in my own classes was the classic Serif vs. Sans Serif debate.

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So according to Hoffman, et al. 2005, it turns out that the real key may be READABILITY. When asked about their preferences for projected fonts on screen, these were the top choices in order of preference. It is interesting that 3 of the 4 are, in fact, sans serif fonts, but don’t be so quick to throw out stylistic yet highly readable fonts like Times if they work for your presentation.


Hoffman B, White A, Aquino N. (2005) “Screen text readability: Ease, accuracy, and speed of some common computer typefaces.” IVLA Conference Proceedings

Exley K, Dennick R. (2009) Giving a lecture: From presenting to teaching. 2nd edition. New York, New York: Routledge

Attention: Part 1

One of my theories is that effective presentations are a fight for attention.

While I was preparing a recent talk, I came across the following video:

I was amazed at the fact that we can miss the gorilla if our attention is focused on something else. When I gave my talk, I showed this video and around 20% of people missed the gorilla!