Supernormal stimulus
Animals exhibiting, or responding to, characteristics that represent a supernormal stimulus usually display them as a result of selective pressures.
[4] Tinbergen studied herring gulls, and found the chicks peck at the red spot located on their parent's bill.
Following his extensive analysis of the stimulus features that elicited food-begging in the chick of the herring gull, he constructed an artificial stimulus consisting of a red knitting needle with three white bands painted around it; this elicited a stronger response than an accurate three-dimensional model of the parent's head (white) and bill (yellow with a red spot).
[citation needed] The core observation that simple features of stimuli may be sufficient to trigger a complex response remains valid, however.
In 1979, the term supernormal stimulus was used by Richard Dawkins and John Krebs to refer to the exaggeration of pre-existing signs induced by social parasites, noting the manipulation of baby birds (hosts) from these, to illustrate the effectiveness of those signals.
[5] In 1983, entomologists Darryl Gwynne and David Rentz reported on the beetle Julodimorpha bakewelli attempting to copulate with discarded brown stubbies (a type of beer bottles) studded with tubercules (flattened glass beads).
[7] Another example of this is the study made by Mauck and colleagues, where they evaluated the effects of a plant pathogen named cucumber mosaic virus or CMV.
[9] Butterflies use olfactory cues, but primarily rely on visual forms of communication, due to wind and temperature affecting their sense of smell.
[9] A more dramatic contrast of color (or movement pattern) resembling, but further emphasizing the traits of the female butterfly, could alter this usual behavior in males.
Cuckoo chicks are often successful because their begging calls, the supernormal stimulus, are representative of an entire reed warbler brood.
These calls will cause the host parent to primarily invest energy into the parasitic chick and provide it with additional food resources.
[11] As a result, this shows a maladaptive behaviour of the host reed warbler as it is investing into a chick that is not biologically related, which does not provide reproductive fitness gain.
Harvard psychologist Deirdre Barrett argues that supernormal stimulation governs the behavior of humans as powerfully as that of other animals.
[15] Furthermore, Pazhoohi et al. (2019) using eye tracking confirmed that lower than optimal waist-to-hip ratios are supernormal stimuli and they may generate peak shifts in responding.
These results show that the exaggeration and "supernormalization" of key features linked to attractiveness, such as eye and lip size, are frequently found in art.
