The detection threshold is the smallest amount of a substance or stimulus that can be perceived by the human senses. Other terms for detection threshold include limen, absolute threshold, and minimum perceptible level. The limen refers to the level at which a stimulus becomes just detectable. The absolute threshold is the smallest amount of a stimulus that can be detected 50% of the time. The minimum perceptible level is the smallest amount of a stimulus that can be detected reliably. These terms are used in various fields such as psychology, biology, and chemistry to describe the sensitivity levels of tests and experiments.