Noise and Sensitivity Flashcards
Can we control noise?
No
We have only access to our subjective perception.
Why is this a problem?
Science is objective, not subjective. Moreover, the information gotten is obtained verbally.
What does the overlap mean?
It means that trials look exactly the same. This makes the task difficult to do and so it makes you try to optimise the performance which will lead to some errors.
What can you do about the overlap?
Set yourself some internal criterion.
We have only access to our subjective perception.
Why is this a problem?
Science is objective, not subjective. Moreover, the information gotten is obtained verbally.
Can we control noise?
No
Sensitivity (d’)
Your sensitivity to a stimulus is illustrated by the separation between the distributions of your response to noise alone and to signal plus noise.
Related to the distance or degree of overlap of the two distributions.
What would the graph look like if d’=0?
The two graphs would overlap
Is d’=1 considered high or low?
Low
Is the criterion for saying “yes” or “no” affected by external factors?
Yes, these could lead to false alarms and misses
Are sensitivity and the criterion related?
No, the criterion is independent of the sensitivity.
Bias
Reflects the general tendency to say more/less “yes” than “no”
Give an example, where your criterion would move from the middle to the left.
If you move your criterion from left to right, how will the sensitivity be affected? And why?
Sensitivity remains the same since the hits and false alarms decrease in a proportional manner.
What does ROC stand for?
Receiver Operating Characteristics curves
What do ROC (Receiver Operating Characteristic) curves represent?
In studies of signal detection, it is the graphical plot of the hit rate as a function of the false alarm rate.
In the graph, where does the chance performance falls?
On the diagonal
Describe the “Good performance” (high sensitivity)
”blows out” towards the upper left corner
