Citation

Troland LT. J. Exp. Psychol. 1917; 2(1): 1-33.

Copyright

(Copyright © 1917, American Psychological Association)

DOI

10.1037/h0071652

PMID

unavailable

Abstract

Discusses measurement of visual stimulation intensities, dealing with: (1) the significance and usefulness of photometric, as compared with radiometric, measurements (2) the problem of the proper method for general photometry; and (3) the influence of pupillary size upon visual stimulus intensity. The various meanings of the term intensity are discussed, and the fundamental significance of photometric and radiometric measurements are considered, together with the relation between radiant energy and light. It is claimed that photometric equations will be more useful in the study of visual-physiology than will radiometric equations. The problem of heterochromatic photometry is addressed, and on the basis of studies of the method of flicker, it is claimed that the method of photometry should be taken up whenever 2 compared lights show a color difference. Finally, the photon is defined as a unit of physiological stimulus intensity. (PsycINFO Database Record (c) 2012 APA, all rights reserved)