Detection theory entered psychology as a way to explain detection experi-
experiments, in which weak visual or auditory signals must be distinguished from
a "noisy" background. In Signal Detection Theory and Psychophysics
A966), David Green and John Swets portrayed observers as decision mak-
makers trying to optimize performance in the face of unpredictable variability,
and they prescribed experimental methods and data analyses for separating
decision factors from sensory ones.
Since Green and Swets' classic was published, both the content of detec-
detection theory and the way it is used have changed. The theory has deepened to
include alternative theoretical assumptions and has been used to analyze
many experimental tasks. The range of substantive problems to which the
theory has been applied has broadened greatly. The contemporary user of
detection theory may be a sensory psychologist, but more typically is inter-
interested in memory, cognition, or systems for medical or nonmedical diagno-
diagnosis. In this book, we draw heavily on the work of Green, Swets, and other
pioneers, but aim for a seamless meshing of historical beginnings and cur-
current perspective. In recognition that these methods are often used in situa-
situations far from the original problem of finding a "signal" in background
noise, we have omitted the word signal from the title and usually refer to
these methods simply as detection theory.