Ernst Weber – One of the Founders of Psychophysics

Ernst Weber

Ernst Heinrich Weber
(June 24 1795, Wittenberg, Germany -January 26 1878, Leipzig, Germany)
Nationality: Germany
Category: Scientists
Occupation: Physiologists, Psychologists
Specification: Empirical Psychology, Psychophysics
Unique distinction: One of the founders of Psychophysics, the predecessor of experimental psychology.
Gender: Male

1. In observing the disparity between things that are compared, we perceive not the difference between the things, but the ratio of this difference to the magnitude of things compared.
2. …the perceivable difference between one stimuli and the next, depends on the magnitude of the stimulus itself. The ratio between these is constant.

Achievements and contributions:

Social and professional position: Ernst Weber was a German physiologist and psychologist.
The main contribution to (Best known): He was regarded as a predecessor of experimental psychology and  One of the founders of Psychophysics, the branch of psychology that studies the relations between physical stimuli and mental states. He is known chiefly for his work on the investigation of subjective sensory response (sensations) to the impact of external physical stimuli:  weight, temperature, and pressure.
Contributions: Ernst Weber experimentally determined the accuracy of tactile sensations, namely, the distance between two points on the skin, in which a person can perceive two separate touches. He discovered the two-point threshold – the distance on the skin separating two pointed stimulators that are required to experience two rather than one point of stimulation.
In 1834 he conducted research on the lifting of weights. From his research, he discovered that the experience of differences in the intensity of sensations depends on percentage differences in the stimuli rather than absolute differences. This is known as the just-noticeable difference (jnd), difference threshold, or limen.
Similar observations were made on other senses, including sight and hearing.

Weber’s law
He formulated Weber’s law:
(ΔI/I = k – constant),

where I is the original intensity of stimulation,
ΔI is the addition to it required for the difference to be perceived,
k is a constant is known as Weber’s constant.
For lifting weights, the ratio was one to 40. That is, for any standard unit of 40, subjects would notice a difference if one more unit were added to the weight.
The constant is different for each sense (for the intensity of  light-1/100, sound -1/10).
Weber also described an absolute threshold for all senses, is the smallest detectable level of a stimulus.
Weber’s works were considered by the English-American  psychologist Edward Titchener to be “the foundation stone of experimental psychology.”
Especially important was his transfer of experimental methods of physiology in the psychology field.
Honours and Awards: Foreign Corresponding Member of the St. Petersburg Academy of Sciences (1869).
Major works: “Anatomia comparata nervi sympatici» (1817); “De aure et auditu hominis et animalium” (1820); «Tractatus de motuiridis” (1822), “Der Tastsinn und das Gemeingefühl” (1851); “The Sense of Touch and the Common Sensibility”.

Career and personal life:

Origin: Ernst Weber was born Wittenberg in Germany.  His father was Michael Weber, a professor of theology. Weber was the third of 13 children in the family. Weber was the eldest of three brothers who all made important contributions to science.
Education: Weber learned Latin in secondary school, and began to study medicine in 1811 at the University of Wittenberg. He received his Doctor of Medicine degree M.D. from this University in 1815, specializing in comparative anatomy.
Influenced by: Johann Christian Rosenmüller, Ernst Chladni Ludwig, Wilhelm Gilbert
Career highlights: In 1818 he was appointed Associate Professor of Comparative Anatomy at Leipzig University, where he was made a Fellow Professor of Anatomy and Physiology in 1821.
Weber was a professor at the University of Leipzig from 1818 until 1871.
In 1821 he was the chair of human anatomy which in 1840 was joined with physiology and in 1865 chair of physiology was relinquished to Carl Ludwig.
Around 1860 Weber worked with Gustav Fechner on psychophysics, during which time he formulated Weber’s Law.
Later Gustav Fechner discovered the law (S = k log R), named the Fechner-Weber law because it was based on the theory advanced earlier by Ernst Heinrich Weber.
Personal life: He devoted his life to science and research.
Zest: With his brother Eduard Friedrich Weber, 1806-71, he discovered the inhibitory power of the vagus nerve (1845). With another brother, Wilhelm Eduard Weber, 1804-91, a German physicist he made studies of acoustics and wave motion.
He wrote (1825) a book on wave motion. Also, his brothers together made a study of walking.