Psychophysics and Signal Detection Theory Flashcards
Just Noticeable Difference
- smallest difference in stimuli that is perceivable
- Ernst Heinrich Weber
- Each JND is perceptually equivalent
Difference threshold
smallest difference you can perceive
absolute threshold
smallest physical intensity you can perceive
Methods of constant stimuli
- measure all the way up and all the way down
- Method of limits: ascending/descending, switch when answer changes
- staircase method: go back one intensity rating as soon as as there is a change in response
- adjustment method: let participant to adjust intensity
Solution to problem of stimulus magnitude ratings
cross modality matching: try to find commonalities across different sensory mediums.`
Weber Fraction
small weber fraction means high discriminability
Fechner
-discovered that JND is perceptually equivalent
Fechner’s Law
S = k log(R)
- takes into account subjective perception
- K is related to Weber’s fractions to account for different senses
Definition of an absolute threshold
-the sensory intensity at which a stimulus is detected 50% of the time
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General labeled magnitude scale
a cross modal scale that allows difference in perception
why is pain logarithmic?
alarm function, as we get closer to injury it is more painful as biological warning
Modulus
- a given stimulus with an assigned rating
- can be used to then compare to other relevant stimuli
Steven’s Power Law
- S = aI^b
- There is a relation between stimulus energy and perceived intensity
- allows for exponential or logarithmic functions`
Cross Modality Matching
- ask people to rate a stimuli on on a scale of a different sense
- how sweet is a coke, on a scale of dB
sensitivity (in signal detection theory)
- how well can you distinguish signal from noise
- sensitivity = Hits - False Alarms