Lecture 3 Flashcards
why do people perceive things at different times (signal detection theory)
there is no direct link between ideas (sensations) and reporting them
for signal detection theory, (the noise and square experiment) will there be more instances when you clearly see a square when there is one or will there not be a square
in general, there will be more instances when you clearly see a square when there is one
what is the notation for sensitivity when calculating it
d’
what is sensitivity (d’)
how well can you distinguish the stimulus from the noise?
Your sensitivity to a stimulus is illustrated by what (the equation)
the separation between the distributions of your response to noise alone and to signal plus noise
D’~= Hits – False Alarms
(D’ is more or less equal to hits munis false alarms)
what if your sensitivity is 0
then you cannot distinguish if there is a square or not
what happens when sensitivity increases
distribution becomes farther apart and you are very good at distinguishing signal from noise
what drives sensitivity aka what is the criterion for saying yes vs no (hit or false alarm due to noise)
The criterion for saying yes vs. no can change as a function of several motivational factors related to the consequences of making a false alarm or a miss.
how does bias impact sensitivity
Bias reflects the general tendency to say more/less «yes» than «no».
However, this doesn’t change the sensitivity.
if offered $100 for sensing the square would you say yes or no more to the square being seen
yes
so your proportion of hits and false alarms moves to the left but the actual distribution would not be impacted
if offered $100 and a shock if incorrect for sensing the square would you say yes or no more to the square being seen
distribution would be the same but their particular criteria would be in the middle
if offered shock if incorrect for sensing the square would you say yes or no more to the square being seen
distribution would be the same but their particular criteria would be in the right (they would say yes less often because they don’t want to be wrong)
as you move your criterion from left to right, what happens
hits and false alarms decrease in a proportional manner.
why does your sensitivity index (d’) remains the same despite changes in the response criterion.
as you move your criterion from left to right, hits and false alarms decrease in a proportional manner
what are Receiver operating characteristic (ROC) curves
In studies of signal detection, the graphical plot of the hit rate as a function of the false alarm rate (the bow-like graph)
