After hiding purchases from a partner, people invest more in the relationship out of guilt

Though openness is considered to be a vital part of a healthy relationship, most of us have something we've kept from our partners or other people close to us. This doesn't have to be something big, however: it could be something as small as lying about whether we like their new outfit, or saying we really do want to spend time with their friends this weekend.

A new study in the Journal of Consumer Psychology looks at another secretive behaviour: hiding purchases from those we are in close relationships with. It finds that not only is secret consumer behaviour incredibly common, but that it can actually have a positive effect on our relationships, as we invest more in them out of guilt.

The first study explored how common secret consumption is and what kind of purchases people keep secret. Secret consumption was defined as any behaviour hidden from a partner, such as not telling them about buying a snack, smoking a cigarette, or engaging in a hobby.

A total of 89.5% of participants, couples recruited at a farmer's market, were able to recall a recent behaviour of this kind, and all couples had at least one partner able to recall one. The types of behaviour hidden from partners were pretty ordinary, such as buying things online, eating fast food, or secretly eating meat when following a vegetarian diet. A follow-up study found that participants tended to categorise their secret consumption activities as mundane and "not a big deal".

A second set of studies looked at whether or not people feel guilt when they hide secret consumption from those close to them. Participants, who were recruited via an online platform and who were all in relationships, were told to imagine they had more money in their account than expected and that they would use this money to buy something online that they really wanted. Some participants had to imagine telling their partner about the purchase, and others imagined they would keep the purchase a secret. They then indicated how guilty they would feel.

Participants then completed what they believed was a completely separate task, but which was designed to measure investment in their relationship. They were told that researchers were testing two new subscription services, and that in exchange for helping test the services, they would be given fifteen virtual raffle tickets. Participants had to distribute the tickets between two raffles: one prize was a "date box" subscription that focused on their relationship, and the other a "hobby box" subscription, focusing on themselves.

The results showed a link between feelings of guilt and relationship investment. Those who imagined hiding purchases felt more guilty, and in turn people who experienced greater guilt tended to invest in their relationships through allocating more tickets to the date box raffle as opposed to the personal hobby box raffle.

Next, the team recruited participants currently living with a romantic partner. They read a scenario in which they imagined they had stopped to get a favourite snack on their way home from work: half of the participants were told they had specifically decided to hide the trip from their partner, while the other half were told they had simply forgotten to tell their partner. They then indicated how guilty they would feel, and were asked how likely it was that they would spend the rest of the evening watching their partner's favourite film or doing something for themselves.

Those who were told they had purposefully hidden their purchase from their partner felt greater guilt than those who were told they had forgotten to tell their partner. This, again, led to greater relationship investment, making them more likely to watch their partner's favourite film, once again suggesting that guilt from hiding purchases can lead to a feeling we should put more into our relationships.

Overall, the studies show that hiding consumer behaviour from our partners is extremely common. And while the behaviour looked at in this study was largely mundane, it still had an impact. It made participants feel guilty, firstly, which then led to further relationship investment. Hiding mundane things from our partner, therefore, may not be all bad – and could be seen as having some positive outcomes.

Future research could look at less mundane purchases: hiding debts or expensive items from your partner is likely to have a different impact than knowing you've eaten a chocolate bar behind their back. And it would also be interesting to explore differences in why people hide things from their partners - does secret consumption have the same effect if it is motivated by guilt versus a desire to spare someone's feelings, for example?