Weber's Law: ΔI/I = k. The Just Noticeable Difference (JND) is a constant proportion of the original stimulus. The bigger the stimulus, the bigger the change needed to notice.
Absolute Threshold: The minimum stimulus intensity needed to detect a stimulus 50% of the time. Below this = subliminal.
Difference Threshold (JND): The minimum change in stimulus needed to be detected 50% of the time.
Tags
Weber's LawJNDThresholdSensation
Sense Modality
Original Stimulus
Intensity = 50
WEBER'S LAW: ΔI/I = k
Original (I):50
Weber Fraction (k):1/60
JND (ΔI):0.83
New Threshold:50.83
Example: If you're holding a 50lb weight (k=1/50), you need at least 1lb added to notice the difference. But if holding 100lb, you need 2lb. The JND scales proportionally!