Coffee shops across the US are finding that offering free wireless internet access to customers is leaving a bitter taste. The FT via Pasta and vinegar.

“There are times when 90 per cent of the people in here are surfing the internet,” says Jen Strongin, co-owner of the Victrola Coffee & Art cafe in Seattle. “It has really changed the atmosphere.”

Students of coffee-house culture call it the “zombie effect” people staring silently into their computers, oblivious to those around them.

Zombies are not only anti-social but also bad business. A single laptop user can take up a whole table. It is not unusual for web surfers to eke out a single cup of coffee for hours.