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Text On Your Presentation Slides - The Nerdy Reason Why It Doesn't Work

· presenting,behavioral science

Do you remember being challenged as a kid to try to rub your belly and pat your head at one time?

It was really difficult, right? Your brain has different processing centers, and when called upon to do two things within a single processing center at the same time, it doesn't typically go so well.

Let's think about the typical sales that's packed with text.


Sometimes paragraphs.

Often with tiny font.

We're asking the brains of our audience basically the same thing - to tap their heads and rub their bellies at the same time.

You've created a near impossibility for the human brain to process.

MIT's Earl Miller has been heralded for his work on the concept of multi-tasking in the brain. The bottom line?

Multi-tasking can't be done.

Our brains work like a strobe light, not a spotlight. Our brains are a constant state of assessing, prioritizing, and refocusing attention. When we attempt to use the same area of our brain for multiple tasks at one time, we are doing both -badly.

You want to know why texting and driving is so dangerous? See above.

As it relates to presentations, our brains use different systems to store information. In a typical learning event involving a presentation, those two systems are our visual system and our verbal system - used to store and represent information. (Unless we're selling velvet...or cookies)

When we're able to touch multiple processing centers in the brain with complementary and reinforcing information, that information is more efficiently stored for long term memory. For example, if you see the word "penguin", you can picture a penguin, right?

This phenomenon is called the "Dual Coding Theory", first theorized in the early 1970's under Allan Paivio from the University of Western Ontario, and discussed more deeply in the book, Cognitive Psychology by Robert J. Sternberg.

This is why, when we use slides with images that reinforce what we're saying, we're making an imprint in the brain in two areas at the same time, both associated with one another, ideal for processing, memory and recall.

📣 Your speaking is being processed in the listening brain using their verbal system.

👀 If you're using images, the attending brain is using the visual system to process that information.

However, what happens when you're using sentences requiring the audience to read while you're presenting. What system is processing the reading while listening to what you're saying?

"Well, they're seeing the words with their eyes. So, it must be the visual system."

As it turns out, we're actually using the verbal system to read and process text.

When we read, our brain is basically reading to itself, then listening to what it just read.

In other words, the spoken word and the words we read are processed in the same channel - and when provided simultaneously, our brains make a choice - it can’t do both!

You cannot listen with comprehension & read with comprehension at the same time.

Similar to asking one system to do both the patting of your head and the rubbing of your belly at the same time, when you're asking the brain to listen to the words coming out of your mouth, process those accordingly, then match them up with the text in the form of sentences on your slides, you're asking the brain to multi-task.

And the brain doesn't multi-task well. As a result:

1) Information you're intending to provide is not being processed effectively in the brain.

2) The audience is likely subconsciously disengaging, because our brains like things to be easy.

Slides can be really powerful mechanisms to create memories and impact - when done correctly. They can also be disasters when done wrong.

Get rid of the text. Use images to create optimal processing in the brain.

Here's a video explanation incorporating some of my rudimentary cartooning skills. Ernie & I explain how information is processed when using visuals only while presenting, versus using slides with text.

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