The minimum intensity of physical stimulation required to produce any sensation at all in a person is the

Absolute threshold

the absolute threshold is the smallest amount of a stimulus that a person can detect half the time.

imagine that researchers are conducting an experiment on light detection. In such an experiment, researchers my place participants in a dark room and then ask them to say when they can detect a light stimulus. The smallest amount of light stimulus that the participants can detect is known as the absolute threshold.