THINK that having sex straight away puts the other person off wanting to have a proper relationship with you? Think again.

Scientists believe that getting down and dirty straight away can actually help to start relationships between potential partners - not the reverse.

A team of psychologists have found that sexual desire may play a major role not only in attracting potential partners to each other, but also in encouraging a proper attachment between them.

"Sex may set the stage for deepening the emotional connection between strangers," says the study's lead author Gurit Birnbaum, a social psychologist and associate professor of psychology at the IDC Herzliya.

"This holds true for both men and women. S#x motivates human beings to connect, regardless of gender."

The study, conducted by experts from the Israeli-based Interdisciplinary Center Herzliya and the University of Rochester's Department of Clinical and Social Sciences in Psychology, looked at heterosexual relationships.Contrary to popular belief that men are more likely than women to initiate relationships when turned on, they found that both s#xes were equally likely to want to connect when sexually aroused.

Participants were introduced to a new acquaintance of the opposite s#x in a face-to-face encounter.

In four interrelated studies, scientists found that sexual desire can trigger behaviours that can promote emotional bonding during these encounters.

"Although s#xual urges and emotional attachments are distinct feelings, evolutionary and social processes likely have rendered humans particularly prone to becoming romantically attached to partners to whom they are s#xually attracted," says co-author Harry Reis, a professor of psychology and Dean's Professor in Arts, Sciences & Engineering at the University of Rochester.

The first study got 36 women and 22 men to lip-synch to pre-recorded music with an attractive person of the opposite sex. Afterwards, they had to rate their desire for that person who they believed to be another participant.

The scientists found that the greater the participant's desire for the insider, the greater their immediacy behaviours towards, and synchronization with, the other person.

Another study involved 50 men and 50 women.

This time, half watched an erotic but non-pornographic video while the other half watched a video of rainforests in South America.

Next, study participants were assigned an attractive opposite-s#x "insider" and told to complete a verbal reasoning task.

The insider pretended to get stuck on the third question and asked the participant for help. The researchers found that those participants who had watched the erotic movie scene were quicker to help, invested more time, and were perceived as more helpful, than the neutral video control group.

So, what does this all mean?

Professor Birnbaum concluded that our sexual behaviour is designed to get us to reproduce, and while sex and procreation aren't dependent on people having relationships, we have developed so that babies generally do have the protection of two parents.

"Throughout human history, parents' bonding greatly increased the children's survival chances," she says.