The term Coolidge effect describes a phenomenon—seen in nearly every mammalian species in which it has been tested—whereby both males and females tire of intercourse with their present partner and get excited at the prospect of a new sexual partner. The biological mechanism: the amount of dopamine declines with a familiar mate, but shoots up with a new mate. This increases the odds of impregnating all willing females.
Pair-bonding species have biological mechanisms that allow them to find sustained relationships rewarding, but these are in tension with the Coolidge effect. How they choose to manage their sexual desire can affect perception of how rewarding a familiar partner is (as compared with a novel one). Engaging in daily bonding behaviors and side-stepping post-orgasmic neurochemical shifts using Synergy seems to mute the Coolidge effect.
Dr. Heike Melzer discusses the Coolidge effect in this TEDx talk. Click “CC” to turn on subtitles.
Also see Post-climax effects – Dopamine.
Humans
Hormones and the Coolidge effect
(Eventual) Stability and Change Across Partnerships
The other man: Knowledge of sexual rivals and changes in sexual behavior
Genomic evidence for MHC disassortative mating in humans
A Descriptive Analysis of Sexual Problems in Long-Term Heterosexual Relationships
Role of Partner Novelty in Sexual Functioning: A Review
Can habituation of sexual responses be elicited in men and women when attention is maintained?
Focusing “Hot” or Focusing “Cool”: Attentional Mechanisms in Sexual Arousal in Men and Women
Habituation of Male Sexual Arousal Effects of Attentional Focus (2001)
Changes in the Magnitude of the Eyeblink Startle Response During Habituation of Sexual Arousal
Allocation of Attentional Resources During Habituation and Dishabituation of Male Sexual Arousal
Changes in erectile response to repeated audiovisual sexual stimulation
Habituation of female sexual arousal to slides and film
Habituation and Dishabituation of Male Sexual Arousal
The Long Term Habituation of Sexual Arousal in The Human Male
Habituation and Dishabituation of Female Sexual Arousal
Repeated exposure to sexually explicit stimuli: novelty, sex, and sexual attitudes
The Habituation of Sexual Arousal
Animals
Nucleus accumbens dopamine increases sexual motivation in sexually satiated male rats
Potency in Male Rhesus Monkeys: Effects of Continuously Receptive Females
How Burying Beetles Spread their Seed: The Coolidge Effect in Real Life
Dopaminergic Circuitry Underlying Mating Drive
Copulation and ejaculation in male rats under sexual satiety and the Coolidge effect
Female Novelty and the Courtship Behavior of Male Guinea Pigs
Dynamic Changes in Nucleus Accumbens Dopamine Efflux During the Coolidge Effect in Male Rats