Signal Detection Theory

Question 1

Signal detection theory is used to explain

Answer 1

Used to explain how stimuli are detected when there is background noise. The more noise, the more difficult to detect a stimulus. The less noise, the easier to detect a stimulus.

Question 2

Signal detection theory allows measurement of sensitivity regardless of __

Answer 2

Response bias.

Question 3

Criterion level

Answer 3

Set by the participant based on outcome prefernces. The minimum intensity at which a signal will be reported as being present.

High criterion- Fewer hits and fewer false alarms.
Low criterion- More hits and more false alarms.

Question 4

Discriminability (d’) is independent of ___

Answer 4

Criterion

Question 5

How is d’ estimated?

Answer 5

Difference between the means of the noise (Mn) and the signal+noise (Msn) distributions divided by the standard deviation of the noise (Sn)

d’ = (Msn-Mn)/Sn

Question 6

How to interpret d’ findings.
Low d’
High d’

Answer 6

Low d’ means there is low discriminability. The noise and stimulus are highly overlapping.

High d’ means there is high discriminability.

Question 7

d'= 0
d'= 1
d'= 4.65

Answer 7

0: Patient was purely guessing
1: moderate performance
4. 65: optimal. Corresponds to hit rate= 0.99 and false alarm rate= 0.01