Signal Detection Theory

Name some factors that affect signal detection

sensory capacity

response proclivity

noise

Define sensory capacity

what the ear “can do”

True or false: response proclivity can be positively of negatively influenced

true! for example, test instruction can influence a person

Define response proclivity

how a subject responds; includes biases and criteria

Name the two types of noise that can affect signal detection

external noise

internal noise

List some examples of external noise

environmental noise

subject fidgeting

List some examples of internal noise

heartbeat

pulse

breathing

Define signal detection theory

a method that attempts to separate auditory sensitivity from response bias

Name the three types of listener biases

liberal

neutral

conservative

Define liberal response bias

when a listener has a high tendency to say yes

Define conservative response bias

when a listener has a high tendency to say no

Name the four possible outcomes for a stimulus response matrix

hit

correct rejection

miss

false alarm

Define a hit in a stimulus response matrix

says yes when signal present

Define a correction rejection in a stimulus response matrix

says no when signal is absent

Define a miss in a stimulus response matrix

says no when signal is present

Define a false alarm in a stimulus response matrix

says yes when signal is absent

True or false: hit + miss can never be greater than 1

True!

What do you put in the boxes of the stimulus response matrix?

the probability rate

What is on the x and y axis of the signal detection theory probability distribution curve?

x-axis: categories (listener’s biases)

y-axis: N/A

If a subject’s response if more liberal then the bell curves moves which direction?

left

Define d prime

the separation between the SN and noise distributions is defined by a parameter

Name some characteristics of d prime

ranges from 0 to 4 (larger number means more separation)

determined by the sensitivity of the system and the energy of the signal

free from response bias

Define d’

measurement of strengths of signal in relation to noise

Hit and false alarm rates can be affected by

response bias

overlap between signal and noise distribution

How can we encourage neutrality in a listener?

give clear instructions

re-test at 1000 Hz

randomizing presentation

Define of receiver operator characteristic curve

provides a simple way to summarizes stimulus response matrices

What is on the x and y axis’s of and ROC curve?

x-axis: false positive rate (1-specificity)

y-axis: true positive rate (sensitivity)

How do you calculate the false positive rate?

FA / (FA + CR)

How do you calculate the true positive rate?

Hit / (Hit + Miss)

Name the characteristics of a lenient/liberal threshold pressure

high hit rate (bad)

high false positive (bad)

Name the characteristics of strict threshold

low hit rate (bad)

low false positive (good)

True or false: the true positive rate should not equal the false positive rate

false; it should equal

Fill in the blank: the _____ the space under the ROC curve the better

larger

Fill in the blank: _________ gives you better diagnostic because there is _____ area under the curve

antiphasic

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