What is the formula used to calculate the just noticeable difference?

The formula used to calculate the just noticeable difference (JND) is indeed (Change / Original) x 100. This formula is based on the principle of comparing the change in stimulus intensity relative to the original stimulus intensity.

The just noticeable difference represents the minimum amount of change in a stimulus that can be detected. By expressing this change as a percentage of the original stimulus, the formula allows us to understand how noticeable a difference is based on the context of the original stimulus level. This concept is rooted in Weber's Law, which states that the JND is a constant proportion of the original stimulus. Therefore, when determining how much change is needed to perceive a difference, it is crucial to relate it back to the original level of the stimulus.

This approach helps researchers and psychologists quantify sensory perceptions and understand how individuals experience changes in various stimuli, whether it be light, sound, weight, or other sensory inputs.