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Alan Stubbs, Constance Stubbs, Lisa Best, Laurence Smith; Perceptual judgments, psychophysics, and biological data. Journal of Vision 2007;7(9):930. doi: https://doi.org/10.1167/7.9.930.
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© ARVO (1962-2015); The Authors (2016-present)
Biologists sometimes make perceptual judgments when collecting data. For example, a scale of lichen quality or an estimate of amount leaf consumption by beetles might be part of data collection. But how accurate are these estimates? Should one base data collection on perceptual observations? And, should we worry about bias in the observations? Can forest quality be estimated only on a relatively imprecise1–5 scale or a 1–7 scale? Or might more accurate estimates be possible? Several psychophysical experiments had people make more direct and specific estimates and these judgments were compared with actual environmental cases. For one experiment, judgment of amount of leaves consumed by beetles was compared with the actual amount consumed. In another, percentage of insects judged as covering an area was compared with the actual percentage. A psychophysical analysis indicated that estimates were quite accurate and generally were within five percent of the actual value. We observed some instances of bias and some of the factors affecting it. The experiments demonstrate that visual estimates of biological data, even those that might seem complex, can be quite accurate. And there are psychophysical procedures that allow us to assess both the level of sensitivity and bias.
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