What Is the Coolidge Effect? Desire, Relationships and Porn

The Coolidge effect is renewed sexual interest when a new partner appears after interest in a familiar one has faded. It has been documented in several animals, though not all, and in people the evidence is indirect.

The name comes from a story about President and Mrs. Coolidge, and the idea is often used to explain why new porn can be hard to resist. This guide separates what has been shown in animals from what has been shown in people, then looks at long relationships and porn. For the wider picture, see our porn addiction guide.

The Coolidge Effect at a Glance

Question	Short answer
What is it?	Rekindled sexual motivation when a new partner is encountered (Koene & Ter Maat, 2007).
Where does the name come from?	An anecdote about President and Mrs. Coolidge (Koene & Ter Maat, 2007).
Which animals show it?	Several species, including rats, though one freshwater snail showed no effect (Fiorino et al., 1997; Häderer et al., 2009).
Does it happen in people?	The evidence is indirect. In hypothetical choices, men picked variety more often than women did (Hughes et al., 2021).
Is it why desire fades in long relationships?	The data don’t show that. In one study of students, women’s desire was lower in longer relationships, and men’s showed no clear link (Murray & Milhausen, 2012).
Does it apply to porn?	A 2022 test found some support in heterosexual men, but its authors called the effects much more nuanced than claimed (Sculley & Watkins, 2022).
Does it happen in women?	Few studies have tested sexual novelty in women, and those have been limited to behavior (Ventura-Aquino et al., 2018).

What Is the Coolidge Effect?

The Coolidge effect is the return of sexual motivation when a new partner appears. Its name comes from a story rather than a study, and the idea has since been tested in several species.

Koene and Ter Maat describe it as “rekindled sexual motivation upon encounter of a new partner” (Koene & Ter Maat, 2007). Ventura-Aquino and colleagues define it as “the renewal of sexual behavior after the presentation of a novel sexual partner,” which “possibly occurs as the result of habituation and dishabituation processes” (Ventura-Aquino et al., 2018). In plain terms, habituation is the fading of a response to something repeated, and dishabituation is its return when something new appears.

The name comes from an anecdote about President and Mrs. Coolidge (Koene & Ter Maat, 2007). The version usually told goes like this: on a farm visit, the First Lady notices a rooster mating often, and the President asks whether it is the same hen each time. He learns it is a different hen. Treat that as the usual telling, not a record of what happened.

Which Animals Show the Coolidge Effect?

Several animals show it, including male and female rats, burying beetles and pond snails. One freshwater snail did not.

• Male rats. Dopamine in the nucleus accumbens, a reward area of the brain, rose when an estrous female was behind a screen and during mating, then returned to baseline during sexual satiety. A new female raised it slightly, and it rose further during renewed mating with her (Fiorino et al., 1997). This is a rat study, so it says nothing direct about people.
• Female rats. Hormonally primed females that had mated for an hour preferred an unknown male to the male they had mated with, and those that could pace the mating spent more time near him (Ventura-Aquino et al., 2016).
• Burying beetles. Males showed more interest in new females, virgin or mated, than in females they had already inseminated. They used the patterns on females’ outer surface to tell them apart (Steiger et al., 2008).
• Pond snails. Lymnaea stagnalis can take either the male or the female role in mating. The snails inseminated new partners after they were no longer motivated to inseminate their original partners (Koene & Ter Maat, 2007).
• A freshwater snail where it wasn’t found. In Biomphalaria glabrata, partner novelty changed none of the measures of sexual motivation, and the authors concluded that the effect “appears inexistent in this invertebrate hermaphrodite” (Häderer et al., 2009).

Does the Coolidge Effect Happen in Humans?

Possibly, but the evidence is indirect. Hypothetical choices and one semen study point toward it, and these studies don’t follow real couples over time.

In two experiments built on hypothetical choices, men were more likely than women to pick variety. In the first, men (281) were more likely than women (353) to spread hypothetical chances of sex across different people, and the sex difference held regardless of the targets’ attractiveness and age. In the second, men (40) were more likely than women (56) to pick a novel person in a hypothetical dating task with photos. The authors read this as support for the Coolidge effect in humans. These were choices people said they would make, not behavior, so they can’t show what people do with partners (Hughes et al., 2021).

A 2015 study enrolled 23 heterosexual men aged 18 to 23, and 21 remained after exclusions. Each man gave a semen sample through masturbation on seven occasions over 15 days, while a 3-minute explicit film segment played on repeat. The first six segments showed the same man and woman in different sexual acts, and the seventh showed the same man with a woman who looked distinctly different. Between the first and sixth samples, the semen measures did not change. With the new woman, semen volume and the total number of motile sperm rose, and men ejaculated more quickly, while the other semen measures did not change. These were lab samples, not sex with partners. The authors suggest that male infertility could be under-diagnosed, since samples for fertility tests are often collected while men view images of women other than their partner (Joseph et al., 2015).

A related lab pattern is habituation. In one study of men, arousal to the same erotic film fell with repeated viewing and rose again when a novel erotic stimulus replaced it (Koukounas & Over, 2000). The desensitization guide covers that research in more detail.

A 2015 review by Morton and Gorzalka covered habituation to erotic stimuli, preferences for number of partners, long-term relationships and affairs. It concluded that “sexual arousal and desire appear to decrease in response to partner familiarity and increase in response to partner novelty in men and women,” and that “this effect may be greater in men” (Morton & Gorzalka, 2015).

None of these studies followed real couples over time. They measured arousal, ejaculate changes or hypothetical choices, or they reviewed that work, so they can’t show how the pattern plays out in a long relationship.

Is There a Coolidge Effect in Women?

Female rats show it, but few studies have tested sexual novelty in women. In people, the evidence suggests the effect may be greater in men, though the question isn’t settled.

Ventura-Aquino and colleagues write that the effect “is well studied in males,” and that studies of sexual novelty in females have been “limited to behavioral aspects” (Ventura-Aquino et al., 2018). In the same paper’s new rat data, female rats’ proceptive behavior, a sign of sexual motivation, declined after four hours of continuous mating, especially in females that couldn’t control the timing. The authors say these data support “important differences between sexual behavior in both sexes,” and they describe the research on habituation in women and men as “a growing research field that needs emphasis in female subjects.”

In people, Hughes and colleagues found that men found it more appealing when their committed partner often changed physical appearance, while women reported changing their own appearance more often than men did (Hughes et al., 2021). These findings rest on what people reported, not on observed behavior.

The 2015 review by Morton and Gorzalka concluded that arousal and desire rise with novelty in men and women, and that the effect may be greater in men (Morton & Gorzalka, 2015). The next section looks at long relationships, where the survey data show lower desire in women in longer relationships, but not in men.

Is the Coolidge Effect Why Desire Fades in Long Relationships?

The survey data don’t fit a simple ‘men get bored’ story. In two studies of students, women in longer relationships reported less desire, while men’s desire showed no clear link with relationship length.

In a survey of 1,865 German students aged 19 to 32 in steady heterosexual relationships, students in longer relationships reported less sexual activity and satisfaction, in both women and men. Sexual desire was lower in longer relationships only for women. The author writes that, because these results are based on cross-sectional data, a longitudinal explanation “is precarious” (Klusmann, 2002).

In a study of 170 undergraduates aged 18 to 25, Murray and Milhausen found that women’s sexual desire was lower the longer the relationship had lasted, even after accounting for age, relationship satisfaction and sexual satisfaction. Men’s desire showed no clear link with relationship length (Murray & Milhausen, 2012).

Neither study found that men’s desire fades with relationship length, so a simple “men get bored” story doesn’t fit these data. Both compared different people, so neither shows how one couple’s desire changes over time.

A 2019 paper on established couples, with three studies using couple, daily-diary, longitudinal and experimental methods, found that doing self-expanding activities (new, interesting or challenging things) together went with higher sexual desire. Higher desire went with greater relationship satisfaction, and the benefits held over time. The authors say the effects can’t be attributed solely to a rise in positive mood, more time together or closeness during the activity (Muise et al., 2019).

Our suggestion: choose one new thing to do together each month, and talk about desire without making the conversation about porn. If porn is part of the picture, porn and relationships covers what the research says about couples.

What Does the Coolidge Effect Have to Do With Porn?

The popular claim is that porn’s “unending novelty” can interfere with men’s pleasure in real relationships. A 2022 test found some support in heterosexual men, and its authors called the effects much more nuanced than claimed.

In 2012, a popular TEDx talk argued that pornography could have “potentially addictive effects” for male viewers, and that pornography’s “unending novelty” may interfere with everyday pleasures in real relationships. Sculley and Watkins describe that claim as underpinned by the Coolidge effect (Sculley & Watkins, 2022).

In their first experiment, Sculley and Watkins analyzed 123 heterosexual men (average age about 24). Each man saw one of three slideshows of the same actresses, showing them having sex, nude or clothed. The men rated the attractiveness of women’s faces and bodies before and after the slideshow, with new women added the second time. Whatever the slideshow, heterosexual men rated familiar bodies as less attractive the second time. Only in heterosexual men did the pornographic slideshows (sex or nude), compared with the clothed one, make familiar women stand out less than new women. This matched one of the authors’ preregistered predictions. A second experiment with 82 gay men found that familiar women were also rated lower on the second viewing, whatever the slideshow. The authors suggest that mere visual exposure to attractive women shifts men’s preferences (Sculley & Watkins, 2022).

The authors concluded that their findings “provide some support” for porn generating “Coolidge-like” effects in heterosexual men, but that these effects are “much more nuanced than claimed.” Contrary to their predictions, viewing porn did not change men’s preference for new bodies over familiar ones. The study tested only men, and it measured attractiveness ratings of photos, not desire for a partner or relationship outcomes (Sculley & Watkins, 2022).

A 2022 brain study points to a related question. It recruited 263 male college students in China to complete a problematic internet pornography use scale, then compared the highest and lowest quarters of scorers: 27 men with high tendencies and 25 with low ones. In an EEG (brain-wave) task, both groups showed a sustained brain response to novel sexual images, and the response was larger in the high-tendency group. The authors suggest that enhanced brain responding to novel sexual stimuli “may facilitate pornographic consumption.” Because the two groups were compared at one point in time, the study can’t show which came first (Wang et al., 2022).

In a 2016 study, 22 men with compulsive sexual behavior showed a stronger preference for novel sexual images than 40 male volunteers did (Banca et al., 2016), and porn and the brain covers the wider brain research.

The fair summary is narrower than the claim. Novelty draws measurable responses in lab and brain tests. But these studies used photo ratings and brain responses, not desire for a partner or relationship outcomes, so they can’t show that porn causes lasting changes in desire or relationships. The guide on why quitting is hard covers how reward and novelty keep the pull going.

What the Coolidge Effect Doesn’t Mean

Four claims go further than the evidence.

• “Men are wired to cheat.” Lab responses, photo ratings and hypothetical choices don’t measure infidelity, so none of them shows that people are wired for affairs. For the cheating question, see is watching porn cheating.
• “Desire in a long relationship is doomed.” The survey data are cross-sectional and compare students in relationships of different lengths. They can’t show what happens to one couple over time.
• “Only men have it.” Female rats show the effect (Ventura-Aquino et al., 2016), and a 2015 review concluded that arousal and desire rise with novelty in men and women, and that the effect may be greater in men (Morton & Gorzalka, 2015). The research on women is thin rather than absent.
• “It proves porn is addictive.” The 2022 test measured photo ratings, not addiction, and its authors called the effects much more nuanced than claimed (Sculley & Watkins, 2022). Whether porn use can become an addiction is a separate debate, covered in is porn addiction real?.

If You’re Trying to Cut Back on Porn

These are practical suggestions, not tested programs.

1. Watch for the “one more new clip” loop. Online porn puts a new face or scene one click away. Notice the moment you start scrolling for something you haven’t seen yet, and pause before you click.
2. Add friction. Put a blocker on every device, and remove the apps or sites you slip on most. How to block porn walks through the options.
3. Ride out the urge. When a new clip feels necessary, wait a few minutes and let the urge rise and fall. Urge surfing shows you how.
4. Bring novelty into real-life intimacy. In a 2019 study of established couples, new shared activities went with higher desire (Muise et al., 2019), so try one new thing with your partner.
5. Track it for a few weeks. Keep a short note of when you go looking for something new and how you feel afterward, and judge progress over weeks rather than one bad day.

When to Get Help

See a therapist or doctor if the search for new material feels out of control, takes hours, or hurts your relationship or work. A therapist who works with compulsive sexual behavior can help you look at what’s driving it, and porn addiction treatment explains the options and how to find one. If your sexual urges of any kind feel out of control, not only around porn, read about hypersexuality.

If you’re having thoughts of harming yourself, or your mood is very low, call or text 988 (the Suicide & Crisis Lifeline in the US), or your local emergency number (988 Suicide & Crisis Lifeline, n.d.).

The Bottom Line

• The Coolidge effect has been documented in animals. Rats, burying beetles and pond snails show it, though one freshwater snail did not.
• In people, the evidence is indirect. Hypothetical choices and one semen study point toward it, but they don’t follow real couples over time.
• A simple “men get bored” story doesn’t fit. In two studies of students, women’s desire was lower in longer relationships, and men’s showed no clear link.
• The porn claim is narrower than it sounds. A 2022 test found some support in heterosexual men, and its authors called the effects much more nuanced than claimed.
• New shared activities are a practical place to start. A 2019 study linked them with higher desire and greater relationship satisfaction.

TrueAlly’s daily check-ins and analytics can help you see patterns over time, including when the “one more new clip” loop tends to show up.

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Sources

• 988 Suicide & Crisis Lifeline. (n.d.). 988 Lifeline. https://988lifeline.org/
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