What if your computer or smartphone could tell if you're happy or sad?

A new device developed by researchers at the Massachusetts Institute of Technology can detect a person's emotions using wireless signals reflecting off a person's body to measure human behaviour.

Researchers from MIT's Computer Science and Artificial Intelligence Laboratory say their EQ-Radio device is 87 per cent accurate in telling if someone is excited, happy, angry or sad.

It's as accurate as an electrocardiogram monitor, which uses a sensor on the body, in measuring heartbeats.

They say it could one day be used by film studios and advertising agencies to gauge audience reaction, in homes to adjust temperature based on mood, or in health care.

MIT's team plans to present the work at a mobile computing conference next month.