If the light is red, please don’t talk to me, or I may turn hulk on you.

That’s the idea behind the guys who invented a warning light which shows when workers are ‘in the zone’ and shouldn’t be disturbed.

FlowLight was invented by a computer scientist Dr Thomas Fritz who noticed that computer coders often placed a traffic cone on their desks when they wanted to be left alone.

FlowLight is a simple concept – green=ok to talk; red=don’t talk to me. The lights changes based on keyboard and mouse activity. When it senses a steady flow of typing, indicative that someone is engrossed in a task, it switches to red. When there is little, or only sporadic activity, it switches back to green, so that colleagues know it is safe to approach.

“When you’re interrupted, it can take a long time to get back into your work and it’s more likely you’ll make mistakes,” said Dr Fritz, an assistant professor at the University of British Columbia in Canada, who started work on the invention when at the University of Zurich in Switzerland.

Dr Fritz said it’s a bit like Skype status, except you don’t have to stop to manually to turn on a light, close your office door or put a cone on your desk. Automatically changing the light is an important feature because when someone is focused on a task, having to put on a sign manually is disruptive.

The light was tested with about 450 employees from engineering firm ABB with positive results.

Although, workers don’t have to worry about being seen as lazy if their lights don’t stay red for long periods of time. FlowLight is designed to only turn red for a maximum amount of time each day regardless of how hard someone works.

Dr Fritz and his PhD student Manuela Züger from the University of Zurich, are now working on a more advanced version of FlowLight with companies in Vancouver to determine whether it can be improved by using biometric sensors to detect heart rate variability, pupil dilation, eye blinks or even brainwave activity.