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A Note on the Evolutionary Significance of "Supernormal" Stimuli
J. E. R. Staddon
The American Naturalist
Vol. 109, No. 969 (Sep. - Oct., 1975), pp. 541-545
Stable URL: http://www.jstor.org/stable/2459810
Page Count: 5
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Animals often respond more strongly to extreme (supernormal) stimuli, never encountered in nature, than to the natural stimulus: birds preferentially retrieve extra-large or extra-speckled eggs, for example. An analogous phenomenon in discrimination learning, the "peak shift," suggests that many instances of supernormality may reflect the action of two factors during phylogeny: (a) asymmetrical selection pressure with respect to responsiveness to the relevant stimulus continuum (e.g., size, speckledness), and (b) independent selection pressures limiting the corresponding properties of the natural stimulus.
The American Naturalist © 1975 The University of Chicago Press