Human memory is a complex and varied phenomenon, and we could delve into its mysteries every day for a hundred years and still have plenty to talk about. But if I had to pick one factor that was absolutely crucial to the operation of memory, I would pick the deceptively simple concept of similarity. Similarity.

We all think we know what that means. An orange is similar to a mandarin; a zebra is similar to a horse; a cup is similar to a glass; my son is similar to his brother. A car is similar to an elephant.


Well, I might think a car was similar to an elephant. Maybe I’m imagining an elephant thundering toward me, kicking up dirt, unstoppable. Or maybe my perceptions are confused. But whether there’s a logical reason for my perception of similarity or not, whether my perception of similarity is shared with other people or not, all that is required for my brain to make the connection is ... that I perceive a connection.

Similarity — perceived similarity — is a crucial ingredient to the connections made in your head. Similarity enables us to make connections that transcend space and time, and enables us to strengthen connections made as a result of a juxtaposition of space and time.

Thus, when you meet a person and he tells you his name is Tom Brown, the first connection is made simply because the name and person are coincident in space and time. And if you leave it there, that connection will most likely be too weak to retrieve on a later occasion.

You can (and should, if you want to remember) employ another critical element to strengthen the connection: repetition (which impacts on the perceived familiarity of the information, but that’s another story). But the new information (this person is named Tom Brown) will be much more firmly lodged in your database, and much easier to find, if you make other connections, connections to information already stored in your memory. Thus, you might associate the name with the book “Tom Brown’s Schooldays”, based on the similarity of names. There might be some physical characteristic of this new person that you can link to a character in the book. If so, you are much more likely to be able to remember this name when you meet the person again. However, if you are barely familiar with the book, and have to stretch your imagination to make any further connection, such as with the characters in the book, then this similarity of names won’t greatly help you.

The important thing when connecting new information to information already existing in your database, is to ensure the existing information is itself easily retrievable, and that the connections you make are not too obscure.

So, to make new memories easily retrievable:

  • look for similarities to existing memories
  • look for similarities that are obvious to you (what other people think doesn’t matter in the slightest)
  • choose existing memories that are themselves easily retrievable

This article originally appeared in the June 2004 newsletter.