What is the Coolidge Effect?

The Coolidge Effect refers to a phenomenon observed in males of various species, including rodents and roosters, where a male can regain his ability to mate when presented with a new female. Initially, after mating repeatedly with the same female, males typically reach a point of exhaustion or a refractory period where they can no longer mate. However, introducing a new female can abolish this refractory period, allowing the male to mate again with renewed vigor 1.

Interestingly, this effect is driven by pheromonal cues. The mere odor of a new female is enough to trigger this response in males, even without the physical presence of the new female. This effect has been demonstrated to work in the opposite direction as well; female rodents also exhibit a similar response where their willingness to mate can be restored by introducing a new male 1.

The Coolidge Effect is tied to dopamine release and prolactin levels. Novelty, such as the introduction of a new mate, boosts dopamine levels, which in turn shortens the refractory period. After copulation, prolactin levels rise, preventing further mating, but novelty can counteract this mechanism. This relationship between novelty, dopamine, and prolactin is not just limited to animals but also exists in humans 2.

For further details, you can explore the discussion in the How Smell, Taste & Pheromone-Like Chemicals Control You on the Huberman Lab.