"In the 16th century, naming men before women became the acceptable word-order to use because of the thinking that men were the worthier sex," said psychologist Dr Peter Hegarty of the University of Surrey.

"This grammar has continued with 'Mr and Mrs', 'his and hers' and the names of romantic couples like Shakespeare's Romeo and Juliet."

"While the original sexist ideas behind this grammar are no longer accepted, we wanted to investigate whether the sexist habit of male names coming before female names still holds true and the psychological reasons why this might be."

Using 10 popular British male and female names and another 10 popular American boys and girls names, the team searched the web using each of the possible male-female name pairs as search terms.

For British name pairs, the male-first name pairings accounted for 79 per cent of the mentions -- male-first mentions were 70 per cent for the Americans.

"These results were found to be statistically significant, and support the idea that gender stereotypes still affect the written language," Dr Hegarty said.

"It has been argued that the male-first effect isn't down to sexism but that it is due to phonological attributes of male names, or because male names come more readily to mind as they are popular and familiar."

"We therefore carried out further studies to investigate whether the male-first finding was a gender stereotyping effect."

A sample group of 121 people were asked to imagine a heterosexual couple who were either 'quite traditional and who conform strictly to gender scripts about how the two genders should behave' or 'non-traditional who deviate radically'.

They were then asked to write down five possible name-combinations for this hypothetical couple.

Participants named the imagined 'traditional couples' men-first more often -- but this effect was not seen in the naming of 'non-traditional' couples.

In a third study, 86 people were asked to write down names of an imagined lesbian or gay couple.

They were then asked to assign attributes such as annual earnings, interest in fashion, interest in sport and physical attributes to each individual.

Participants assigned significantly more of the masculine attributes and fewer of the feminine attributes to the person they named first.

"The results of our studies suggest that people tend to put men, or male qualities, before women," said Dr Hegarty.

"As this is a remnant of the sexist grammar of the 16th century, it would seem that psychologically, we are still sexist in writing."

But Dr Hegarty cautions that the effect does not always apply when dealing with couples that we know well:

"When people address greeting cards to couples, for example, they often put the person that they know best first, whether female or male."