Ernst Heinrich Weber

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Lore & Background

Ernst Heinrich Weber was born on 24 June 1795 in Wittenberg, Saxony, Holy Roman Empire, the son of Michael Weber, a professor of theology at the University of Wittenberg. Influenced early by physicist Ernst Chladni, Weber completed secondary school at Meissen and began studying medicine at the University of Wittenberg in 1811, receiving his MD in 1815 from the University of Halle. He completed his Habilitation in 1817 at the University of Leipzig, becoming an assistant in J.C. Clarus' medical clinic the same year. He became professor of comparative anatomy in 1818 and chair of human anatomy in 1821. Weber's first direct contribution to psychology came in 1834 with work on the sensation of touch (De Pulsu, Resorptione, Auditu et Tactu). He described the just-noticeable difference (jnd), finding that the finest discrimination between weights required an 8–10% difference. He also developed the two-point threshold technique to map touch acuity using a compass technique, and identified Weber's illusion, an 'experience of divergence of two points when stimulation is moved over insensitive areas and convergence of two points when moved over sensitive areas'. With his brother Wilhelm, he launched experiments on the physics of fluids in 1821, publishing Wellenlehre, auf Experimenten gegrϋndet (1825), which became instantly recognized as very important to physics and physiology. He was professor of physiology and anatomy from 1840 to 1866, and returned to the position of professor of anatomy from 1866 to 1871. Later in life, he worked with his brother Eduard on nerve stimulation and muscle suppression, leading to inhibitory responses as a popular therapy of the time. Ernst Weber died in 1878 in Leipzig, Germany.

Reader's Guide

Ernst Heinrich Weber's significance lies in his pioneering application of precise measurement and mathematical relations to sensory psychology, laying the groundwork for experimental psychology as a scientific discipline. His formulation of the just-noticeable difference (jnd) stated that 'we perceive not the difference between the things, but the ratio of this difference to the magnitude of things compared.' Weber's law, as labeled by Gustav Theodor Fechner, established that sensory events can be related mathematically to measurable relative changes in physical stimulus values, expressed as ΔR/R = k, where ΔR is the amount of stimulation needed to produce a jnd, R is the existing stimulation, and k is a constant different for each sense. Fechner took inspiration from Weber's law and developed Fechner's law, claiming a logarithmic relation between stimulus intensity and perceived intensity. Weber's two-point threshold technique helped map sensitivity and touch acuity on the body using a compass technique, determining at what distance two points are perceived as separate. His book Der Tastsinn und das Gemeingefühl was called 'the foundation stone of experimental psychology' by E. B. Titchener. By testing ideas on human subjects and using multivariate experiments with precise measurements, Weber helped establish experimental psychology as a legitimate field, influencing fellow 19th-century psychologists to expand.

Did You Know?

• Weber found that the finest discrimination between weights required an 8–10% difference; for example, a 100 g block needed a second block of at least 108 g to be distinguishable.
• Weber's first direct contribution to psychology came in 1834 with a work titled De Pulsu, Resorptione, Auditu et Tactu.
• Weber's book Wellenlehre, auf Experimenten gegrϋndet (1825) on wave theory was instantly recognized as very important to both physics and physiology.
• E. B. Titchener called Weber's book Der Tastsinn und das Gemeingefühl 'the foundation stone of experimental psychology'.
• Weber's two-point threshold technique used a compass to map sensitivity and touch acuity on the body.