Perception Flashcards
What is the psychophysical function?
Shows the magnitude of a stimulus
x-axis = physical intensity
y-axis = psychological intensity
What is the problem with the psychophysical function?
It is unreliable
Just noticeable difference
Smallest change that can be detected
Just noticeable difference is a _____ of the stimulus intensity
Constant proportion
What does a Weber fraction tell you?
How sensitive each sense is for changes in each stimulus
What is the threshold?
When a stimulus is just perceivable
What is signal detection theory?
A mathematical theory based on the detection of physical signals
Assumption of signal detection theory
Sensitivity to a stimulus is dependent not only on intensity, but on the amount of noise present, the motivation of a subject, and criterion set for responding
What are the outcomes of signal detection theory?
Hit
Miss
False alarm
Correct rejection
What are perceivers’ biases influenced by?
The costs and benefits of the response outcome
Method of constant stimuli
Random frames from skewed GIF shown, asked which ones they can see the stimulus
Method of limits
Start with no stimulus, remove noise until stimulus can be seen
Can be done the other way round to find limit that the stimulus can no longer be seen
Method of adjustment
Give participant control of the stimuli and get them to turn it up/down and say when they can see it
What does ROC stand for?
Receiver operated characteristics
What do ROC curves allow?
Allows you to compare people who have the same sensitivity but different biases
