The Broca-Sulzer effect or Broca-Sulzer phenomenon is an experimental observation related to the

psychophysics Psychophysics quantitatively investigates the relationship between physical stimuli and the sensations and perceptions they produce. Psychophysics has been described as "the scientific study of the relation between stimulus and sensation" or, m ...

of vision. It has two parts, temporal and spatial. In the temporal effect, the perceived brightness of a single flash of light first increases with the flash duration, then reaches a maximum, and decreases for a longer pulse. The maximum is more pronounced and is observed at shorter durations for a stronger illumination; it is reached at approximately 0.1 for a 100

lux The lux (symbol: lx) is the unit of illuminance, or luminous flux per unit area, in the International System of Units (SI). It is equal to one lumen per square metre. In photometry, this is used as a measure of the intensity, as perceived by the ...

flash. Similarly, in the spatial Broca-Sulzer effect, the perceived brightness increases with increasing

angular size The angular diameter, angular size, apparent diameter, or apparent size is an angular distance describing how large a sphere or circle appears from a given point of view. In the vision sciences, it is called the visual angle, and in optics, it is ...

of the flashing object until it reaches approximately 2.5

arcminutes A minute of arc, arcminute (arcmin), arc minute, or minute arc, denoted by the symbol , is a unit of angular measurement equal to of one degree. Since one degree is of a turn (or complete rotation), one minute of arc is of a turn. The na ...

, and then decreases for a larger object. The Broca-Sulzer effect was reported by

André Broca André — sometimes transliterated as Andre — is the French and Portuguese form of the name Andrew, and is now also used in the English-speaking world. It used in France, Quebec, Canada and other French-speaking countries. It is a variation ...

and David Émile Sulzer in 1902. It conflicted with the 1885 report by Adolphe-Moïse Bloch who believed that the perceived brightness monotonously increases with the flash duration. Later research showed that while the Bloch's law may hold for some individuals and for some experimental conditions, the Broca-Sulzer effect is a more general phenomenon.

References

{{reflist, refs= {{cite journal, author=Bloch, A-M. , title=Expériences sur la vision, journal=Comptes rendus des séances de la Société de biologie , volume=37 , issue=28, year=1885, pages= 493–495 {{cite journal, author1=Broca, André, author2=Sulzer, D. , year=1902 , title=La sensation lumineuse en fonction du temps, journal= Comptes Rendus de Séances des l'Académie des Sciences, volume= 134, pages= 831–834, url=https://gallica.bnf.fr/ark:/12148/bpt6k6339096f/f28.image {{cite journal, doi=10.1073/pnas.1213170109, title=Optimizing the temporal dynamics of light to human perception , year=2012 , last1=Rieiro , first1=Hector , last2=Martinez-Conde , first2=Susana , last3=Danielson , first3=Andrew P. , last4=Pardo-Vazquez , first4=Jose L. , last5=Srivastava , first5=Nishit , last6=MacKnik , first6=Stephen L. , journal=Proceedings of the National Academy of Sciences , volume=109 , issue=48 , pages=19828–19833 , pmid=23150557 , pmc=3511764 , bibcode=2012PNAS..10919828R , doi-access=free {{cite journal, doi=10.1016/0042-6989(75)90071-1, url=https://docksci.com/suprathreshold-intensity-area-relationships-a-spatial-broca-sulzer-effect_5e4fbfb9097c479f668b457c.html, title=Suprathreshold intensity-area relationships: A spatial Broca-Sulzer effect , year=1975 , last1=Higgins , first1=Kent E. , last2=Rinalducci , first2=Edward J. , journal=Vision Research , volume=15 , issue=1 , pages=129–143 , pmid=1129960 , s2cid=7585989 Vision

See also

References