London, Mar 5 (IANS): The speed at which we produce facial expressions plays an important role in our ability to recognise emotions in others, a new study suggests.

The study indicates that our ability to form judgements about people's facial expressions has close links with the speed at which those expressions are produced and is also closely related to the ways in which we would produce those expressions ourselves.

"Being able to recognise and interpret facial expressions is a vital part of social interaction," explained lead author Sophie Sowden from the University of Birmingham.

"While we understand the spatial characteristics of an expression -- the way the mouth moves in a smile, for example -- the speeds at which expressions are produced are often overlooked. The ability to pick up on and rapidly interpret these cues could also help people to judge facial expressions even when mask-wearing might limit other visual cues," Sowden added.

For the study, published in the journal Emotion, the team asked people to create facial expressions directed at a camera, and used an open source software programme called OpenFace to track their facial movement.

In the first part of the experiment, the researchers investigated the average speed at which participants produced different expressions.

They were asked to produce 'posed expressions', as well as expressions during speech, and spontaneous expressions were recorded in response to emotion-inducing videos.

Interestingly, they showed differences in speed across emotions depends on the region of the face and the 'type' of expression being considered.

In a second phase of the study, the team investigated what would happen if they captured schematic versions of facial expressions being produced, and manipulated the speeds involved.

In this experiment, the researchers found that as the act of expression was speeded up, people would get better at recognising it as happy or angry, whereas if it was slowed down, people would more accurately identify it as sad.