Sensation threshold is the minimum input to the senses that can produce a sensation, or the intensity of a stimulus that can produce a particular sensation. The concept of “threshold of sensation” was introduced in 1860 by the English psychologist Francis Galton, who studied the dependence of the sensitivity of the human organs of vision, hearing, smell and touch on the strength of the stimulus. He proposed the term "sensation threshold" to describe the minimum stimulus strength required to produce sensation in a given modality. The sensation threshold is the minimum value of the stimulus required for a person to experience a sensation as a signal of the impact of the stimulus. Sensitivity thresholds depend on the type of stimulus and on a number of other factors (physiological state of the subject, age, etc.). In biology, thresholds of sensation are called minimal changes in the strength of stimulation that cause any response in the body.