Signal Detection Theory

The theory of signal detectability (TSD) was developed in the 1950s and 1960s as a way of understanding and explaining how humans process low-level sensory input. TSD incorporated concepts from statistical decision theory, mathematics, engineering, and electronic communications. For sensory psychology, TSD provided a highly quantitative alternative to the classical view that there is a threshold that amounts to a fixed boundary between signals that cannot be detected and those that are perfectly detectable. Instead, TSD asserted that the lower limit of detectability is subject to random influences. [Page 1709]TSD also recognized that the measurement of sensory capability is affected by the observer’s need to make a decision when faced with inconclusive sensory evidence and that observers naturally tend to adopt effective strategies to make ...