But is it true? Reflections on the Sellotape Effect

When I prepare a weekend homily, I take care to check my facts. It’s amazing how often a piece of information which I think I know turns out to be nearly right, but from a different author or source than I first “remembered”.

In this week’s homily, I assert that the more sexual partners a person has, the less strongly bonded that person is likely to become to each one in turn. This was based on a talk I heard in 2009 by Kaye Smith, using a powerful visual illustration with sellotape, and I see that an Irish chastity group uses a similar routine. One British newspaper picked up on this and reported it with great skepticism.

This caused me to wonder whether there was in fact good evidence for what I was going to assert in my preaching. Would this be one of those cases where a factoid is embraced by Catholics who “want it to be true” to support moral teaching? Finding the answer is not straightforward! As a scientist I cannot settle for “anecdotal evidence” – it is important to be rigorous, even though scientists are occasionally pilloried for “proving what everybody knows already”. Further, as a priest who has always been celibate, this is a topic where I am moving well beyond my own lived experience.

First, there IS good scientific evidence that within a monogamous relationship, sexual intimacy becomes less satisfying as the novelty wears off – this effect is known as habituation. This can be measured either by asking the person to comment on their experience of satisfaction (subjective) or less directly, but objectively, by tracking hormones known to have a role in bonding and pleasure, such as oxytocin and vasopressin. A key paper illustrating subjective habituation was published in 1995 by Call, Sprecher and Schwarz.

David Disalvo alludes to psychological research indicating that habituation also accounts for the higher failure rate of second and subsequent marriages, because subsequent marriages can never capture as much novelty as the first pattern of deep sexual encounters. See his book’s section Singing the Habituation Blues.

There is also research by Jay Teachman showing that a marriage is more likely to break down if the spouses cohabited prior to marriage, and more likely to break down if a woman has cohabited with more than one person prior to marriage. Other research broadly supportive of traditional Christian marriage has been gathered by Sir Paul Coleridge’s Marriage Foundation.

To some, sympathetic to the traditional Christian view of marriage, the stance I take on habituation – the reason why it is best to avoid multiple relationships – may seem simply common sense. To others, unwilling to be restricted by traditional norms, and prizing diminishing novelty above security, it may seem unduly paternalistic. Supporters of both positions might well be able to produce anecdotes – from couples who remained chaste until marriage, and from those who have tried multiple relationships yet finally succeeded in forming a strong bond. A scientific approach treats individual anecdotes cautiously, and requires multiple cases generating robust statistics before a conclusion is drawn. My view at this time is that the brief comment in my homily is not proven but is strongly plausible, and in the absence of better evidence, will have to do for now.

My thanks to Dr Foley and Dr Lewis for their assistance with this research.