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Psychophysics
study of relationship between physical stimuli and sensation and perception they envoke
Psychophysics purpose
understanding these relationships help us quantify and predict how humans perceive sensory information
Weber’s Law
JND between 2 stimuli is proportional to magnitude of stimuli
Fechner’s Law
logarithmic relationship between physical magnitude of a stimulus and its perceived intensity
Steven’s Power Law
nonlinear relationship between stimulus intensity and perceived sensation across different sensory modalities
Signal Detection Theory
framework for understanding how people make decisions about perceiving signals amid noise
Signal Present
Is Target There?
Yes: Hit
No: False Alarm
Signal Absent
Is Target There?
Yes: Miss
No: Correct Rejection
Signal Noise Distribution
basic theory is that strength of signal and noise are represented by distributions
D
measures discriminability - noise curve and signal
C
criterion - response bias
Absolute Threshold
minimum amount of stimulus e required for a person to detect presence of a stimulus, 50% of time
Difference Threshold
JND - smallest detectable difference between 2 stimuli
Relative Threshold
deviations from baseline KND
Method of limits
experimenter changes the stimulus intensity in small steps → participate indicates when they detect stimulus
Method of Constant Stimuli
Multiple stimuli of varying intensities present → participant indicates which ones they detect
Method of Adjustment
the participant adjusts the stimulus intensity until they can detect it
