London: Just look down at your keyboard. A study says that typing with your left hand can make you sad.

Scientists aren't sure why typing words with one's left hand makes one feel more negative about what one writing, but think it may have to do with the fact that the right hand is responsible for fewer letters than the left.

The arrangement of keys on a standard "Qwerty" keyboard means an user's left hand, which covers 15 letters, actually has to work harder than his or her right hand which is only responsible for 11, a daily reported.

Experiments showed that the trend applies to words coined before and after the invention of the Qwerty keyboard, and to made-up words in English, Dutch and Spanish.

The trend was strongest in new words first used after the arrival of the keyboard, suggesting the layout of keys could be influencing the evolution of new words, according to the scientists.

Writing in the 'Psychonomic Bulletin and Review' journal, they said that the study "suggests that the Qwerty keyboard is shaping the meanings of words as people filter language through their fingers".

The scientists said: "It appears that using Qwerty shapes the meanings of existing words and abbreviations get adopted into the lexicon and 'texticon' by encouraging the use of words and abbreviations whose emotional valences are congruent with their letters' location on the keyboard." The Qwerty layout was developed in 1868 to solve the problem with the alphabetical layout of typewriters, which caused certain neighbouring keys to jam during fast typing.

Frequently paired letters were separated on opposite sides of the keyboard, and the letters of the brand name 'Type Writer' were all included in the top row to help salesmen demonstrate their product.

Almost 150 years on the decision has had a fundamental impact on the way we perceive language, researchers said.

In fact, in their study, the scientists analysed more than 1,000 words from each of three languages, and found that on average mainly left-sided words were perceived slightly more negatively than those on the right.

For every additional letter on the right hand side compared with the left, words were viewed on average four per cent more positively, and vice versa.

A second test using only modern words revealed a stronger effect, while a slight trend also appeared in a third experiment asking volunteers to rate made-up words.

Kyle Jasmin of University College London and Daniel Casasanto of The New School for Social Research, New York, who led the study, said: "Widespread typing introduces a new mechanism by which changes in the meaning of words can arise.

"People responsible for naming new products, brands, and companies might do well to consider the potential advantages of consulting their keyboards and choosing the 'right' name."