If a potential customer enjoys your advert, they are more likely to buy your product.

It's a simple enough concept, but it is extremely difficult to know how well your advert is being received in the real world.

The team collected more than 3200 videos of people, whose faces were filmed by their own computer's webcam as they watched three adverts online during the Super Bowl in 2011.

Now a new system could help advertisers know exactly how their latest offering is going down with viewers, just by watching their face.

The system, developed by Daniel McDuff and colleagues at the Massachusetts Institute of Technology Media Labs, looks at how muscles in the face move in response to watching a video.

Software can then classify what counts as positive facial responses and smiles during the video and from that predict which adverts the viewer most enjoys.

After each commercial -- one for Doritos, one for Google and one for Volkswagen -- the viewers were asked if they liked the video and whether they would want to watch it again.

In tests, the system made correct predictions more than 75 percent of the time.

The system would be a boon for advertisers trying to grab the attention of potential customers on the internet.

In future, the system could be used to personalize adverts for viewers as they watch programmes online, depending on their reaction, or as a more effective way of testing how good a new advert is at appealing to customers. Thank you.