Couples about to tie the knot may be wise to listen to their intuition before walking down the aisle, research suggests.
A study has found that even at a subconscious level, lurking doubts at the start of a marriage are a good indicator of a less than blissful future.
Psychologists conducted tests on 135 couples who had been married for less than six months, then checked their progress over a four-year period.
They found that the feelings participants expressed verbally about their marriages had little bearing on their later happiness. Instead, it was their inner "gut-feelings" - only revealed by the tests - that counted.
The US study was based on the premise that emotions buried under the surface still affect people's physical responses, which can be measured in the laboratory.
In the experiment, photos of volunteers' spouses were flashed on a computer screen for just a third of a second, followed by a positive word such as "awesome" or "terrific", or a negative one such as "awful" or "terrible".
Participants simply had to press a key to indicate whether the word they were seeing was positive or negative.
"It's generally an easy task, but flashing a picture of their spouse makes people faster or slower depending on their automatic attitude toward the spouse," said lead researcher Dr James McNulty, from Florida State University.
"People who have really positive feelings about their partners are very quick to indicate that words like 'awesome' are positive words and very slow to indicate that words like 'awful' are negative words."
The opposite was also true, he said. When participants had negative feelings about their partners - ones they might not even want to admit to themselves - it took them longer to respond to positive words, and less time to respond to negative ones.
After the tests, the couples were questioned about their level of relationship satisfaction every six months.
Those who had unwittingly revealed negative or lukewarm feelings towards their partners reported the most marital dissatisfaction four years later.
"Everyone wants to be in a good marriage," said Dr McNulty. "And in the beginning, many people are able to convince themselves of that at a conscious level. But these automatic, gut-level responses are less influenced by what people want to think. You can't make yourself have a positive response through a lot of wishful thinking.
"I think the findings suggest that people may want to attend a little bit to their gut. If they can sense that their gut is telling them that there is a problem, then they might benefit from exploring that, maybe even with a professional marriage counsellor."
Writing in the journal Science, the researchers concluded: "Although they may be largely unwilling or unable to verbalise them, people's automatic evaluations of their partners predict one of the most important outcomes of their lives - the trajectory of their marital satisfaction."