Toronto, Jan 19 (IANS): Whether they are growls of anger, the laughter of happiness or cries of sadness, humans pay more attention when an emotion is expressed through vocalisations than we do when the same emotion is expressed in speech.

It takes just one-tenth of a second for our brains to begin to recognise emotions conveyed by vocalisations, a study said.

The researchers believe that the speed with which the brain 'tags' these vocalisations and the preference given to them compared to language, is due to the potentially crucial role that decoding vocal sounds has played in human survival.

"The identification of emotional vocalizations depends on systems in the brain that are older in evolutionary terms," said lead study author Marc Pell from McGill University in Montreal, Canada.

"Understanding emotions expressed in spoken language, on the other hand, involves more recent brain systems that have evolved as human language developed," Pell explained.

The findings were published in the journal Biological Psychology. 

The researchers were interested in finding out whether the brain responded differently when emotions were expressed through vocalisations (sounds such as growls, laughter or sobbing, where no words are used) or through language. 

They focused on three basic emotions - anger, sadness and happiness - and tested 24 participants by playing a random mix of vocalisations and speech.

The researchers found that the participants were able to detect laughter more quickly than vocal sounds conveying either anger or sadness. 

But, interestingly, they found that angry sounds and angry speech both produced ongoing brain activity that lasted longer than either of the other emotions, suggesting that the brain pays special attention to the importance of anger signals.