What concept describes the change in perception relative to the original stimulus?

The concept that describes the change in perception relative to the original stimulus is known as the Just Noticeable Difference (JND). This principle is grounded in psychophysics—the study of how physical stimuli are translated into psychological perceptions.

Just Noticeable Difference quantifies the smallest amount by which a stimulus can change and still be perceived as different. For instance, if you have a weight of 100 grams, the JND might be 2 grams, meaning you would only notice a difference if the weight changed to 102 grams or more. This concept illustrates how our perception of stimuli is based not just on the stimuli themselves, but also on their relation to a baseline.

Thus, JND explains the human ability to perceive changes in stimuli in a relative manner, which is crucial for understanding sensory processing and perception. Other concepts mentioned, such as the threshold principle, adaptive response, and signal detection theory, deal with different aspects of perception, such as the minimum level of stimulus needed for detection, how organisms adapt to consistent stimuli, and distinguishing between signal and noise in perception. However, the focus of relative changes in perception squarely rests with the Just Noticeable Difference.