The size-weight illusion, where larger objects of equal mass are perceived as lighter than smaller ones, was first evidenced by Augustin Charpentier in 1891. Working primarily within the fields of medicine, ophthalmology, and psychiatry, he established a career focused on the physical mechanisms of human vision and sensory perception during a period of significant medical advancement.
Academic Appointments and Early Career
Born in 1852 in Argenton-sur-Creuse, France, Charpentier completed his medical studies in Limoges before defending his doctoral thesis in Paris in 1877. This initial work explored vision through the retina. Between 1875 and 1878, he served as an assistant to Edmund Landolt. In 1878, he joined the University of Nancy, working alongside Émile Léon Poincaré in the department of physics and medicine. By 1879, he achieved the rank of full professor of medicine. His academic standing grew significantly, leading to his role as a national correspondent for the physics and chemistry division of the Académie nationale de médecine in 1888.
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Charpentier focused his research on optics and the physiological responses of the eye. He developed a differential photoptometer to measure retinal sensitivity under conditions of low light intensity. He also investigated and named retinal oscillations. His 1891 experiments provided the first systematic evidence for the size-weight illusion, which demonstrated a discrepancy between physical mass and sensory perception. Later, in 1900, he participated in the first International Congress of Physics held during the Exposition Universelle, where he chaired the biophysics session in place of Jacques-Arsène d'Arsonval.
Scientific Investigations and Recognition
During his later years, Charpentier published fifteen papers concerning N-rays, a form of radiation discovered by Prosper-René Blondlot in Nancy that was subsequently determined to be an illusion. His contributions to science were recognized by several prestigious bodies. He became a member of both the French Academy of Sciences and the Académie nationale de médecine. His research efforts secured the Buignet prize in 1883, the Montyon Prize in 1885, and the La Caze prize in 1901. He received state recognition as an officer of public instruction in 1890 and was appointed a knight of the Legion of Honour in 1906. He died in 1916 in his place of birth, Argenton-sur-Creuse.
Fast facts
- Born: 1852, Argenton-sur-Creuse
- Died: 1916, Argenton-sur-Creuse
- Citizenship: France
- Doctoral thesis year: 1877
- Academic post: University of Nancy
- Key discovery: Size-weight illusion
- Legion of Honour: 1906
Questions readers ask
What was the size-weight illusion?
It is a sensory phenomenon discovered by Charpentier where individuals perceive larger objects as lighter than smaller objects, despite both items sharing the same mass.
Did Charpentier study N-rays?
Yes, he authored fifteen papers on the subject of N-rays, which were later identified as an illusory phenomenon.
Achievements
- Held posts at University of Pont-à-Mousson
- Fields: medicine, ophthalmology and hygiene
