Neuroscientists are able to spot people in love from their brain scans which is why it is next to impossible to lie about it to researchers.
With the help of brain scans, neuroscientists can now tell that you're madly in love.
By charting brain activity with an fMRI (functional magnetic resonance imaging) machine, scientists can spot telltale regions of your brain glowing joyously when you look at a photograph of your beloved.
In addition, they can also tell as to whether you and your loved one will be happily married years from now, or bitterly separated by studying your brain activity alone.
Several years ago, Xiaomeng Xu, now a postdoctoral fellow at Brown University School of Medicine, and her colleagues performed fMRI scans on 18 Chinese men and women who reported being in the early stages of romantic love.
Though all the study participants showed clear signs of love - looking at the face of their beloved triggered a flurry of activity in the areas of their brains involved in reward and motivation - the researchers identified subtle differences between the individuals' brain scans.
When the team followed up with the study participants 18 months later to learn how their budding relationships had turned out, they found a surprisingly strong correlation between certain characteristics in the original brain scans and the participants' relationship status a year and a half later. The team detailed its results in the journal Human Brain Mapping in early 2010.
Now, another two years have passed, and the researchers have contacted 12 of the original study participants. Half of the participants are still in the relationships they had just begun at the time of the brain scans three and a half years ago; the other six aren't. Among the admittedly small sample, there is a striking divide between the original brain activity of the people whose relationships lasted and those whose relationships fell apart.
"Even with this small number of people, the results are really interesting," said Lucy Brown, a leading expert on the neuroscience of love at Albert Einstein College of Medicine and a member of the research team.
Two key aspects of the participants' brain activity correlated with their relationship longevity, Brown said.
Among the people whose relationships became long-term, looking at a picture of their beloved "caused a decrease in activity in regions that we associate with making judgments, and also a decrease in activity in systems associated with a person's sense of self," she said.
"Sense of self" can be thought of awareness of one's own existence, interests and desires.
These two brain responses, and the associated behavioural traits, suggest that a promising relationship is one in which people refrain from judging their new partners, and instead, tend to overrate them, even finding the positive aspect of a patently negative trait.
A promising new romance is also one in which people give great importance to their loved one's interests and desires, even to the subjugation of their own. Both these tendencies seem to be "a huge help in the longevity of a relationship," Brown told Life's Little Mysteries, a sister site to LiveScience.
The researchers plan to conduct a larger-scale study to see if the correlation between relationship longevity and the two fMRI signatures - corresponding to the two behavioural traits - is as strong as their small data set implies.
They also intend to investigate whether certain people more easily exhibit the traits in question, and are thus inherently more suited to long-term attachments, than others.