Psychophysical Methods 2 Flashcards
What’s the signal detection theory
Threshold determined in an experiment or clinical procedure may be influenced by a number of factors
-provides useful model to predict effects of certain factors
Factors involved in signal detection theory
Decision criteria
Attention
Motivation
Internal neural noise
A stimulus produces a neural _____ that is _____ on the neural _____
Signal
Superimposed
Noise
Observer’s ____ is to _____ the signal and noise combination from the background noise alone
Task
Differentiate
Neural noise or activation present in the absence of a stimulus
Neural noise
How is noise distributed over time?
Randomly distributed over time and randomly fluctuating over time
A stimulus causes a constant level of neural activation - a signal - to be added to the noise
Noise + signal
If the stimulus is presented many times at various noise levels, the distribution of noise (N) it’s shifted in which direction by what amount, and in order to produce what?
Right
Constant amount
Produce a noise pulse signal distribution (N + S)
What is present in the absence of the signal?
Neural noise
What’s the observer’s task for noise + signal?
To determine if what he or she is seeing (or hearing) is noise or signal plus noise
What occurs when the stimulus results in neural activity that exceeds the threshold criterion?
Hit
What occurs when the activity does not exceed the criterion?
Miss
What occurs when the neural activity exceeds the threshold criterion in the absence of a stimulus (i.e., a blank trial)
False positive
What occurs when the activity is below the criterion during a blank trial?
Correct reject
As the signal becomes larger the distributions of N and N + S become further apart, and detectability (d’) of the stimulus inreases
High detectability of signal
