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The signal detection theory definitely is a theory that predicts how and when one detects the presence of weak stimuli for all intents and purposes admits background noise. The detection of stimuli involves many sensors, such as decision and sensory processes, which is fairly significant. Factors that influence this detection really include the intensity of the stimuli, basically physical factors fairly such as fatigue and healthiness, and psychological factors for all intents and purposes such as motivation and expectations in a very major way.