Signal Detection Theory

I often like to change a complex psychological definition into a precise and clear one that everyone understands, but the definition for Signal Detection Theory is pretty straight forward. Here is one that I found in one of my texts: "Signal Detection Theory holds that the detection of a stimulus depends on both the intensity of the stimulus and the physical and psychological state of the individual." And that's really all it is....Your ability or likelihood to detect some stimulus is affected by the intensity of the stimulus (e.g., how loud a noise is) and your physical and psychological state (e.g., how alert you are). For example, when you walk to your car that is parked in an empty parking lot late at night all by yourself, you might be much more aware of noises because the situation is somewhat threatening (you are primed and listening carefully to hear anything and everything). In this case, you may hear some slight noises that you might otherwise not hear if you were in a different situation that was not as threatening. Thus, your ability to detect signals or noises has been affected by these factors. See what I mean?