Later, she might go out and buy Pepsi Max instead of her usual choice, Diet Coke - because she knows her partner prefers the Coca-Cola drink, say the researchers from the University of New Hampshire.
"By unconsciously choosing the opposite brand their partner prefers, people might feel better without realising it," said lead researcher Dr Danielle Brick, assistant professor of marketing at the Peter T. Paul College of Business and Economics at New Hampshire.
"We found that consumers are using brand choice as a form of behaviour to deal with conflict in relationships."
The pattern was identified in a series of psychological experiments with volunteers.
In one study, nearly 300 participants were assessed for 'relationship power' - defined as how much control they had in the relationship - before answering questions about their partners' preferred brand choices in six categories, including coffee, toothpaste and shoes.
They were then tricked by being told they were taking part in a visual acuity task related to letters. In fact, they were subconsciously linking their partners' names to words that evoked frustration, sadness or neutral emotions.
Finally, the volunteers were asked to choose what brands they preferred in the same six categories.
Partners who were low in relationship power and had been primed to feel frustrated were more likely to select brands that were the opposite of what their partners preferred - known in marketing as "oppositional brand choices".
Those lacking relationship power and induced to feel sad, however, were more likely to pick a brand that suited their partners' taste.
"When people are sad, they tend to be more passive because they are ruminating, so they are not feeling actively oppositional toward their partners," said Dr Brick.
Co-author Dr Gavan Fitzsimons of Duke University said that future research could look into whether couples actually made 'spiteful' choices against their partners wishes. In the current study, the participants were only asked to select brands for themselves.
"Further research could examine whether there are differences between oppositional and spiteful brain choices.
"If someone were to make a truly spiteful choice then one would choose the brain that is opposition to the brad that the partner likes when the partner actually has to consume it.
"We found some evidence to suggest that making oppositional brand choices can reduce relationship frustration."
The findings, published in the Journal of Consumer Psychology, have implications for marketing, say the researchers.
"Marketers assume consumers are making conscious, deliberate choices, but actually there are other factors, sometimes even outside of their conscious awareness that are influencing their decisions," Dr Brick added.
This article was originally published on The Telegraph
