W7-Signal-Detection-Theory-Notes.docx - 6A Signal Detection...

6A Signal Detection Theory Part 1
One of the early goals of psychologists was to measure the sensitivity of our sensory systems. This
activity led to the development of the idea of threshold .
Threshold – the least amount of stimulation needed for a person to be able to see, hear, feel, or detect
stimulus.
Unfortunately, one of the problems with this concept was that even though the level of stimulation
remained constant, people were inconsistent in detecting the stimulus. An approach to resolving this
dilemma is provided by the Signal detection theory.
Signal Detection Theory – a psychological theory that quantifies the response of an observer to the
presentation of a signal in the presence of noise. It is a quantitative technique that may be used to
understand how people detect signals from the environment. This technique was developed at the
University of Michigan and psychologists use it to measure absolute thresholds of humans in detecting
sound.
Examples and application of Signal Detection Theory:
A radiologist may decide based on evidence if a tumor is malignant (signal) or benign (noise).
A polygraph expert has to determine if the data from a polygraph indicates that a person has lied (signal)
or told the truth (noise).