Hi, I thought you may like this Mentalrobics exercise from Braingle.com:
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Tip of the Tongue

Everyone has had the experience where you have something on the tip of your tongue, but you can't remember it. One way to try to recall the information is to think around it [ For more on 'think around it' go here: http://www.braingle.com/mind/208.html ]. Another way is to stop thinking about it and let your unconscious mind process it for a while. Sometimes the fact will jump into your mind the moment after you stop thinking about it. Normally, once you remember the fact, it seems obvious and you can hardly imagine why you couldn't remember it in the first place.

This proves a few facts about memory. First, it shows that memory is not all or none. In other words, sometimes you can recall a partial or incomplete memory. Second, just because the information is in your mind doesn't mean you can recall it whenever you want. Organizational problems sometimes prevent recall for information that exists.
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For more mind exercises: http://www.braingle.com/mind/