the magnitude of the stimulus that causes or changes perception, sensation; qualitative indicator of the analyzer’s sensitivity. Perception thresholds are inversely proportional to the quantitative indicator of the corresponding type of sensitivity. The minimum value of the stimulus that first begins to cause a sensation is called the lower absolute threshold of perception. The upper absolute threshold of perception is the size of the stimulus at which the sensation either disappears or qualitatively changes (for example, it turns into pain, as happens when the volume of sound or the brightness of light increases). A minimal increase in the size of a stimulus, accompanied by a barely noticeable change in sensation, is called difference in the horn of perception. The ratio of the value of the difference threshold to the value of the initial stimulus is determined as the differential threshold.