Signal Detection Theory
The theory of signal detection theory evolved from the development of communications and radar equipment the first half of this century. It migrated to psychology, initially as part of sensation and perception, in the 50's and 60's as an attempt to understand some of the features of human behavior when detecting very faint stimuli that were not being explained by traditional theories of thresholds.
The situation of interest is this:
What makes this different from traditional threshold theories is that the subject makes a decision, a cognitive act, as to whether the signal is present or not. This basic sensory act of determining if a stimulus occurred now is understood to have a cognitive component.
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Now what can happen in this situation. If the signal is present the person can decide that it is present or absent. These outcomes are called hits and misses. If the signal is absent the person can still decide that the signal is either present or absent. These are called false alarms or correct rejections (CR) respectively.
A common way to display these outcomes is below in Table 1.
Where to from here: