Signal Detection Theory & Applications Flashcards
To understand the basic tenets of signal detection theory as well as some of its basic applications.
What are the two possible accurate responses and the two possible inaccurate responses that are possible in a given SDT task?
Accurate
- Correct detection
- Correct rejection
Inaccurate
- Type 1 Error
- Type 2 Error
What is a Type I Error or False Alarm?
An error in which an individual claims that a signal is present, when in reality, it is not present.
What is a Type II Error or Miss?
An error in which an individual claims that a signal is not present, when in reality, it is present.
What is a correct detection or hit?
When an individual claims that a signal is present and it really IS present.
What is a correct rejection?
When an individual claims that a signal is not present and it IS not present.
What are the two distributions that SDT is concerned with?
- Noise distribution
- Signal + noise distribution
What is d prime (d’)?
D prime is the distance between the peaks of the two curves (i.e., the noise distribution and the signal + noise distribution). It is a measure of an individual’s perceptual sensitivity. As d’ decreases, sensitivity decreases – signal and noise graphs overlap and signal becomes harder to detect. As d’ increases, sensitivity increases – signal and noise graphs separate and signal becomes more detectable.
How is probability of a signal likely to affect an individual’s response criterion?
If the signal probability is more likely, the response criterion (Xc) should be lowered (shifted to the left). If the signal probability is less likely, the criterion should be raised (shifted to the right).
During a jury trial in which a guilty verdict will lead to the death penalty, which type of error is worse to make?
Type I Error
When a doctor is looking at a patient’s x-ray for signs of cancer, which error is worse to make?
Type II Error
