In 1980 Swedish psychologist Anders Ericsson conducted an experiment with a college student named Steve. Steve had an average memory and at the beginning of the experiment could recall about seven numbers.

After 20 months he’d gradually improved and could recall 80 numbers. Here, by the way, is what that looks like.

23543528771345606671024564819535421575302502045807097036542464822713098725403681

How did a young man with ordinary memory powers accomplish this extraordinary feat?

Through chunking. Let me give you a simpler example. Stare at these numbers for five seconds and see how many you can recall:

186 5191 419 4517 7618 12

Most people can’t recall more than a few of the 20 numbers. But now turn the page and look at the same string of numbers for five second and see how many you can recall:

1865 1914 1945 1776 1812

A person with normal memory will recall all 20 of these numbers effortlessly because they’ve been “chunked” into memorable dates in U.S. military history.

Chunking is how Steve remembered 80 numbers. He was a long-distance runner and early on figured out he could recall 4-digit chunks that looked like times in a race; for example:

23:54
35:28
77:13
45:06
66:71
60:66
71:02

In short order he was able to recall not just seven digits but seven four-digit “chunks” – or 28 letters. Using this technique of mentally visualizing track scores, combined with other chunking tricks, Steve eventually got up to 80 numbers.

True, training and development aren’t about memorizing numbers, but this landmark experiment tells us two important things:

1. How the human brain copes with complexity and cognitive overload. Steve found, without being coached in any way, a technique for grouping an overwhelming amount of data into small chunks that were both memorable and manageable.
2. That we, when we’re playing a training role, will be far more effective if we “chunk” learning concepts. We reduce cognitive overload when we present learning concepts that are short, simple and memorable.