caa a22 4500 467929432 CHVBK 20180406152939.0 cr unu---uuuuu 170328e20060201xx s 000 0 eng 10.1007/s10658-005-4732-9 doi (NATIONALLICENCE)springer-10.1007/s10658-005-4732-9 The Role of Psychophysics in Phytopathology: The Weber-Fechner Law Revisited [Elektronische Daten] [Forrest Nutter Jr, Paul Esker] The accuracy and precision of disease severity assessment data might be improved if there was a better understanding of how the laws of psychophysics actually relate to the theory and practice of phytopathometry. In this regard, we utilized a classical method developed in the field of psychophysics (the method of comparison stimuli) to test Horsfall and Barratt's claim that raters cannot accurately discriminate disease severity levels between 25% and 50% because, according to the Weber-Fechner law, visual acuity is proportional to the logarithm of the intensity of the stimulus. We show for two pathosystems, wheat leaf rust and grapevine downy mildew, that raters can accurately discriminate disease severity levels between 25% and 50%, and that although Weber's law appears to hold true, Fechner's law does not. Furthermore, based upon our results, the relationship between actual (true) disease severity (X) and disease severity estimated by raters (Y) is linear, not logarithmic as proposed by Horsfall and Barratt. Springer, 2006 accuracy nationallicence Fechner's law nationallicence phytopathometry nationallicence precision nationallicence Stevens's power law nationallicence Weber's law nationallicence Nutter Jr Forrest Department of Plant Pathology, Iowa State University, 351 Bessey Hall, 50011, Ames, IA, USA aut Esker Paul Department of Plant Pathology, Iowa State University, 351 Bessey Hall, 50011, Ames, IA, USA aut European Journal of Plant Pathology Kluwer Academic Publishers 114/2(2006-02-01), 199-213 0929-1873 114:2<199 2006 114 10658 https://doi.org/10.1007/s10658-005-4732-9 text/html Onlinezugriff via DOI 1 research-article jats NATIONALLICENCE 856 40 https://doi.org/10.1007/s10658-005-4732-9 text/html Onlinezugriff via DOI NATIONALLICENCE 700 1- Nutter Jr Forrest Department of Plant Pathology, Iowa State University, 351 Bessey Hall, 50011, Ames, IA, USA aut NATIONALLICENCE 700 1- Esker Paul Department of Plant Pathology, Iowa State University, 351 Bessey Hall, 50011, Ames, IA, USA aut NATIONALLICENCE 773 0- European Journal of Plant Pathology Kluwer Academic Publishers 114/2(2006-02-01), 199-213 0929-1873 114:2<199 2006 114 10658 Metadata rights reserved Springer special CC-BY-NC licence nationallicence BK010053 XK010053 XK010000 NATIONALLICENCE NATIONALLICENCE NL-springer