7 x 20 = Overload

Put 7 bullet points per slide on 20 slides and you have 140 reasons why you are creating cognitive overload for your audience.

140_2 Jason Kottke pointed out the results of a new study in cognitive science that found that people have a hard time processing more than four variables at a time, let alone 140:

"In their experiment, 30 academics were presented with incomplete verbal descriptions of statistical interactions between fictitious variables, with an accompanying set of graphs that represented the interactions. The interactions varied in complexity — involving as few as two variables up to as many as five…

"The researchers found that, as the problems got more complex, participants performed less well and were less confident. They were significantly less able to accurately solve the problems involving four-way interactions than the ones involving three-way interactions, and they were (not surprisingly) less confident of their solutions.

"And five-way interactions? Forget it. Their performance was no better than chance. After the four- and five-way interactions, participants said things like, ‘I kept losing information,’ and ‘I just lost track’."

The findings are right in line with the work of short-term memory expert Nelson Cowan, who updated the classic 1956 George Miller article which had placed the capacity of short-term memory at seven items, plus or minus two. Nelson told me in an interview that our updated understanding is that "people can retain in mind only about 3 or 4 independent ideas on average; though individuals vary from about 2 to about 6."

Many people justify 7 bullet points per slide by citing the George Miller article, but what’s always missing in the arithmetic is the total number of bullet points across all of the slides; e.g., 7 bullets per slide times 20 slides equals 140 bullet points. Any single slide is part of a whole experience in which you’re trying to help someone understand something, so to get the whole picture you really have to add up all the bullets.

If our short-term memory can hold 3 or 4 items and we’re seeing 140, you’re probably not surprised that there is a scientific validation for those times you’ve felt overwhelmed, confused or bored by an information presentation approach.

But an interesting tidbit from this new research is the relationship of cognitive overload to confidence. I think this cuts both ways – when an audience is forced to watch 140 list items with no cognitive guidance, it undermines their confidence in their ability to understand. They think there’s something wrong with them, not the presentation approach. But it also debilitates the presenter – when you are unclear about the underlying coherence of your message beneath all of those bullets, your confidence is shot too, diminishing the quality of your public speaking.  Nobody wins here.

We can move forward by figuring out the 3 or 4 most important things out of those 140 bullet points. One effective technique is a classical logic tree, which is built-in to the story template and can help you create a hierarchy out of your ideas. Bren had an apple fall out of the hierarchy tree yesterday when he encountered it while working on his story structure for his makeover and said:

"At first I wasn’t sure about the 3-step roadmap (I thought: There’s more than three things to do!), but then I realized there are only three boxes in the 5-minute column. I’m starting to ‘get it’."

The need for identifying top-level ideas is not new – what’s new is giving it appropriate expression through a PowerPoint platform. 

When we make it to the top of the tree of clarity, both audiences and presenters will greatly improve their confidence and we can move on with the business of understanding one another.

Tip: Look at your PowerPoint presentation in Slide Sorter view – exactly where are the 3 or 4 things you want people to remember and apply in their lives? Watch how Jim and Bren find out as they work on their own story templates, or give it a try on your own presentation makeover.

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