Signal Detection Theory
Signal Detection Theory
Signal detection theory is a principled explanation for decision making under noisy conditions. All real decisions are made under a certain degree of uncertainty determined by extrinsic environmental conditions and intrinsic neural and cognitive processes.
A typical situation of concern to the theory is the simple forced choice, a type of binary classifier system. In this situation, a subject must decide whether some type of signal (perhaps a flashing light) is present in trials that contain the signal and trials that do not contain the signal. If during a signal trial the subject decides a signal is present, the decision is called a hit; if the subject decides a signal is not present, the decision is called a miss. If during a non-signal trial the subject decides a signal is not present, the decision is called a correct rejection; if the subject decides a signal is present, the decision is called a false alarm. A variable called the internal response is what "causes" the subject to make a certain decision, and is often related to a neuronal parameter such as firing rate.
The internal responses for signal and non-signal trials are described by Gaussian probability distributions; in this Demonstration, the red distribution is for the non-signal situation and the green distribution is for the signal situation. Discriminability is a measure of the extent to which a subject can distinguish between a signal situation and a non-signal situation and is quantified by the distance between the means of both distributions. The criterion is a variable usually set by the subject; it is a strategy for decision making in which an internal response above the criterion "causes" a "yes, signal" response and an internal response below the criterion "causes" a "no, no signal" response. Also shown in this Demonstration is a receiver operating characteristic (ROC) curve, which shows how the hit rate and false alarm rate vary with discriminability and noise.
External Links
External Links
Permanent Citation
Permanent Citation
Garrett Neske
"Signal Detection Theory"
http://demonstrations.wolfram.com/SignalDetectionTheory/
Wolfram Demonstrations Project
Published: January 16, 2008