Couples’ unconscious feelings can be used to better predict their future happiness than what they actually say, according to a study of newlyweds.

The study, published in Science, followed 135 couples for the first four years of their marriage and found that gut-level feelings, which they were either unwilling or unable to verbalise, were a better indicator for the outcome of the relationship.

Jim McNulty at Florida State University and colleagues assessed couples’ conscious attitudes toward their relationships by getting them to complete a questionnaire that asked how satisfied they were with their relationships on a scale from one (very unhappy) to ten (perfectly happy). Then, to calculate their gut-level feelings – what psychologists call a person’s “automatic attitude” – they tested individuals’ reaction times to positive (“awesome”) and negative (“horrible”) words after being shown photographs of their spouses, or others as a random control.

The psychologists found people who had a more positive attitude towards their spouse were faster to respond to positive words and slower to respond to negative words. Those who were slower to respond, on the other hand, became more dissatisfied with their marriage over the same period.

Consciously held opinions, the study suggests, seem to have little bearing on how happy couples remain over time. The responses that were willingly given in written questionnaires did not correlate with future happiness.

Unconscious measures may be a useful way of seeing past the rose-tinted glasses that most couples likely have when they get married. Previous studies have suggested that couples routinely overestimate the likelihood of marital success. Who, after all, would enter into marriage believing that it won’t last? And that’s in spite of discouraging divorce rates.

McNulty suggests unconscious misgivings might reflect problems that people are not willing to admit to themselves. “Conscious attitudes, the ones we think about and voice, are based on a lot of thought,” he said, but this can also make us susceptible “wishful thinking”.

But having a “positive illusion” was not necessarily a bad thing in a relationship, said Scott Stanley, a relationship expert and professor of psychology at the University of Denver. Still, he said couples shouldn’t hide their heads in the sand when it comes to confronting their true feelings.

“Positive illusions, and maintaining them, is generally a great thing over time in a relationship where the beliefs and perceptions of the partner are positive and warranted.”

If people “were more fully aware of their true, gut feelings before marriage, they’d break up,” he said, but it may well be something they need to do.

McNulty said the study would prove helpful to couples who were motivated to resolve problems. Instead of suppressing issues with a relationship, which could lead to unhappiness or a dreaded divorce, it may be helpful to put in more work from the start.