Coolidge effect
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In biology and psychology, the term Coolidge effect describes a phenomenon – seen in nearly every species in which it has been tested – whereby males show continuously high sexual performance given the introduction of new receptive females.[1][2]
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[edit] Origin of the term
The term comes from an old joke, according to which President Calvin Coolidge and his wife allegedly visited a poultry farm. During the tour, Mrs. Coolidge inquired of the farmer how his farm managed to produce so many fertile eggs with such a small number of roosters. The farmer proudly explained that his roosters performed their duty dozens of times each day.
"Perhaps you could point that out to Mr. Coolidge," pointedly replied the First Lady.
The President, overhearing the remark, asked the farmer, "Does each rooster service the same hen each time?"
"No," replied the farmer, "there are many hens for each rooster."
"Perhaps you could point that out to Mrs. Coolidge," replied the President.
[edit] Empirical evidence
The original experiments with rats followed this protocol:[3] A male rat would be placed into an enclosed large box with four or five female rats in estrus. He would immediately begin mating with all of the female rats repeatedly until eventually exhausted. Although the females would continue nudging and licking him to continue, he would not respond. However, if a novel female were introduced to the box, he would become alert and find the ability to mate once again with the new female. This phenomenon is not limited to Rattus norvegicus.[4] It is attributed to an increase in dopamine levels and its subsequent effect upon the limbic system.[5]
While the Coolidge effect is usually seen demonstrated by males – that is, males displaying renewed excitement with a novel female – Lester and Gorzalka developed a model to determine whether or not the Coolidge effect also occurs in females. Their experiment, which used hamsters instead of rats, found that it does occur in lesser degrees in females.[6][7]
[edit] See also
[edit] References
- ^ Reber AS & Reber E, the Penguin dictionary of psychology, 3rd ed. Penguin London ISBN 0-14-051451-1
- ^ Brown, R. E. (1974). Sexual arousal, the Coolidge effect and dominance in the rat (Rattus norvegicus). Animal Behaviour, 22, 634–637. (doi:10.1016/S0003-3472(74)80009-6)
- ^ Beach, FA. and L, Jordan, "Sexual Exhaustion and Recovery in the Male Rat," Quarterly Journal of Experimental Psychology 8, (1956: 121-33.)
- ^ Wilson, J, R. Kuehn, and F.A. Beach, "Modifications in the Sexual Behavior of Male Rats Produced by Changing the Stimulus Female," Journal of Comparative and Physiological Psychology 56 (1963): 636–44).
- ^ Fiorino DF; Coury A; Phillips AG "Dynamic changes in nucleus accumbens dopamine efflux during the Coolidge effect in male rats" J Neurosci, 1997 Jun, 17:12, 4849–55 Abstract at: http://www.biopsychiatry.com/ratsex.htm
- ^ "Effect of novel and familiar mating partners on the duration of sexual receptivity in the female hamster", Behavioral Neural Biology 1988 May;49(3):398–405. Abstract at: http://www.ncbi.nlm.nih.gov
- ^ Biopsychology by John Pinel, 6th edition.
