Out of Sight, Out of Mind

statement	A implies B
converse	~A implies ~B
contrapositive	~B implies ~A

The contrapositive of a statement is exactly equivalent to the original, but the converse is a separate statement, and not equivalent.

association	If I see it, then I think of it.
converse	If I don't see it, then I don't think of it.

Formalism aside, the main point I want to make here is that when taken not simply as an interesting observation but as a usable fact about the mind, this converse to association is as powerful a principle as association itself.

How would one use such a fact? I myself mostly use it to create an environment free of distraction, one that promotes calm thought. The idea of creating a separate work space, even if one works from home, is another example—in the work space, the distractions of home are out of mind, and vice versa.

In fact, even the idea of having rooms at all is an example. The other day I was reading an article about how to design levels for 3D computer games, and one of the tips was that large rooms should be separated from one another by opaque barriers, so that the graphics engine doesn't have to compute more than one room at a time—what is this if not the principle of “out of sight, out of mind”?!

Finally, I found another example of how to make use of the principle in an excerpt from Walden Two.