This is the 2007 version. Click here for the 2017 chapter 08 table of contents.

Supernormal Stimuli

A bird tries to retrieve an abnormally large egg while ignoring realistic eggs

Lorenz once put a football-sized model egg by the nest of a bird. The bird tried to retrieve it using the same action pattern it would use for a normal sized egg. If a normal egg was placed alongside the giant one, the bird made fruitless attempts to retrieve the big egg while neglecting its own normal-sized egg. Lorenz called the exaggerated sign stimulus a supernormal stimulus. Supernormal sign stimuli are bigger or more intense than normal. They elicit a larger-than-normal response from the animal.

What is a supernormal stimulus?

Why would a bird prefer a grotesquely large egg to a natural one? Manning (1972) speculates that larger eggs are usually healthier, and giant eggs never occur in nature, so there is no need for an upper limit on the animal's preference for larger eggs. The animal generally improves its genetic success by retrieving a larger egg first. (Actually, there is some upper limit. A bird would not attempt to retrieve a house-sized egg.)

How might facial make-up be a supernormal stimulus for humans?

Do humans respond to supernormal stimuli? Perhaps. Humans have a biologically "wired-in" response to the human. (Babies at the age of two months will smile at an oval shape with two dark circles where eyes should be.) If the human face is a sign stimulus or releaser, then cosmetics create supernormal stimuli. Rouge exaggerates rosy cheeks; lipstick exaggerates red lips; eyebrow pencil and eyeliner exaggerate the darkness of eyes; false eyelashes exaggerate eyelashes. A made-up face may elicit a larger than normal response.

Write to Dr. Dewey at

Don't see what you need? Psych Web has over 1,000 pages, so it may be elsewhere on the site. Do a site-specific Google search using the box below.

Custom Search

Copyright © 2007-2011 Russ Dewey