Signal Detection Theory (SDT). Where you will never know if you did see that item or not. Imagine I asked you to remember the word book. Remember it yet? Ok, good. Now, was the word I asked you to memorize municipal? No? Is the word I asked you to remember book? Oh good. I am glad you remembered. Let me ask you, did you really know the word was book? Note, this is not a philosophical exercise of existentialism, although I often do wonder. Well, there is this one theory that proposes that you never actually knew that the word was book. Huh?
Consider a world where the word book has some level of familiarity, maybe you’re old pals. In this very same world, you have to also assume that the word municipal has some level of familiarity, maybe you’ve seen it around. Let’s say one day after encountering one of the words you go home and someone asks you about the words you saw that day. Now, it is known that in this world, each word has some level of familiarity. How does one then choose? I guess it’s possible to say that all words have different levels of familiarity. We can then say that words observed today contain a higher level of familiarity then words presented yesterday. It’s important to point out at this time that it behooves you to make a decision based on some criterion. “Fine,” you say. And you set your criterion at 6 A.M.. Any word that has a lower level of familiarity then expected to have since 6 A.M. is considered to be irrelevant in the conversation. And so you proceed to tell your friends about the words you saw today.
Great, now you know SDT. I guess it’s more appropriate to say, you now know SDT in the context of recognition memory. But I am sure you are sharp as a tack and get how this system can be applied to many other fields. Furthermore, I am almost certain you are able to formulate the mathematical structure based on the description I have provided. Well just in case you forgot, I know you didn’t, but just in case you did here you go:
Speaking of the devil (what a funny phrase), recognition memory is a peculiar study. For instance, there are memory researchers interested in claiming that the human memory system lives in the world I described above.