Friday, December 30, 2016

So that's where the Rule of Threes comes from.

When I began working at Grey media school as we fondly called it in the 80's I was told: "People need to see your ad three times before they will remember it, so make sure you have at least a frequency of three."

When I wrote my first book I looked for the underlying research for the principle to no avail.  But this year I found it.  So I thought I would share.

It dates back to 1885, when German psychologist Hermann Ebbinghaus published his pioneering study of memory.  This included the development of the forgetting curve, which established the fact that in the absence of reminders, after 31 days retention drops to 21%. 

But, he also discovered the spacing effect, which showed that periodic reminders can have a significant positive effect on learning and retention.

Note that in the model, after the third repetition retention is approximately 75%.[i] Add a fourth review within the 30 day time frame, and the percentage increases to ~85%, which is why most plans are created to run for an entire month.

So now you know too.

[i]Murre, J. and Dros, J. (2015, July 6)  Replication and Analysis of Ebbinghaus' Forgetting Curve.  Retrieved May 28, 2016, from

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