The Limit of Memory Is Seven

I wrote on another blog about how memory affects the user experience (UX) of design, but a slice of that information for this post is about Miller’s Law. This “law” came about from a 1956 paper in psychology with a great title – “The Magical Number Seven, Plus or Minus Two” (though the subtitle is less fun: “Some Limits on Our Capacity for Processing Information”) by George A. Miller who was in the Princeton University Department of Psychology.

What is the law? The short explanation is that we can keep ~7 bits of information in our mind short term.

You might say “Only 7?”  But 7 is not a bad thing or a good thing. It’s just a thing.

Miller showed through experiments showed that the number of perceptual “chunks” an average human can hold in working memory (which is a component of short-term memory) is 7 plus or minus 2.

An example of this chunking would be if I asked you to remember this string of letters:  l, r, p, l, e, d, a, a, e .  If I asked you 10 minutes later, could you remember those 9 chunks?  Most people can’t recall them all in order.

Of course, if I rearrange them into a perceptual gestalt chunk – paradelle – you could easily remember them.

If I give you a 20-word list of random words, you are very likely to remember later 5–9 of the words. That has been shown in hundreds of experiments.  7 + or – 2.

Something else observed in relation to Miller’s Law is the primacy, and recency effect. In that 20-word list, you are most likely to remember the words at the beginning of the list and the end. This tendency to recall the first and last items in a series best and the middle items worst is also known as the serial position effect. I actually learned that idea in a writing course. They will remember the beginning and the end of your piece better than the middle. A strong start and finish with the weaker content dead center.

You can take Miller’s Law into your day. How many items can you juggle at once? Don’t exceed 9 bits. Organize things into chunks.

Our days are filled with an increasing amount of information. When it is not organized, it becomes much harder to complete tasks. I made up a new To Do list form that has 5 items. I know that in the past I have had too many things on the list. If I have more than 5, I’m going to either put them on the next list or try to chunk them. For example, “post office dropoff” and “pick up prescription” are one chunk, one trip out of the house.  for the purposes of survival (navigation/gaining income).

Millers Law tells us that we have a finite amount of information we can process. Information overload distracts us and negatively affects performance.

* NOTE *   Things are getting worse. New research seems to indicate that we only get to hold 4 things in short-term memory.