Ever wonder why phone numbers are only 7 to 8 digits long? (excluding country and area codes)? Well here’s why. Bell Labs, a former American research institute of the U.S. national telephone company, was tasked with finding out the right number of digits to use for phone numbers. The story goes that Bell Labs asked renowned Harvard professor George A. Miller to conduct research to understand the amount of information that most people can memorise in a sequence.
Miller published an article, based on his findings, titled The Magical Number Seven, plus or Minus Two[1], which has since become a classic in the field of psychology. Through his research, Miller found that most people are capable of storing up to seven pieces of information, with a standard deviation of two (give or take two). These findings then led Bell Labs to make their phone numbers consist of seven digits.
The Art of Chuncking
Contemporary scholars have since built upon Miller’s work. It is now widely agreed upon that the most efficient way that most people retain information is using three chunks of information[2]. Yes that’s right – chunks. Consider phone numbers, if you have to remember a phone number that is 7 to 8 digits long, do you memorise each number individually? Well, probably not. Chances are that you break this number down to bite-sized chunks that are easier to remember. This technique is called ‘chunking’, when you group individual pieces of information into larger chunks, so that you can memorise it with ease. Have you noticed that our phone number is frequently listed as (010) 414 8869 instead of 0104148869?
The Golden Rule of Three
This rule can also be applied to persuasion techniques. This powerful technique is used by many authors, speechwriters and advertising agencies. The rule of three can also be used to help you to memorise your story or presentation. Most importantly, limiting your story to three main points will make it more memorable for your audience.
