How is the absolute threshold quantitatively defined?

The absolute threshold is quantitatively defined as the smallest level of stimulus that can be detected 50 percent of the time. This concept is rooted in psychophysics, which examines the relationship between stimuli and perception. The determination of the absolute threshold occurs through various experimental methods that seek to find the minimum intensity needed for a person to perceive a stimulus reliably in half of all trials.

This value is used to measure sensory sensitivity and varies across different sensory modalities — for instance, what is easily detectable by touch, sound, or sight can differ widely among individuals and situations. Therefore, the 50 percent detection rate is a critical standard as it reflects a consistent point of awareness a subject has about a stimulus.