If you get motion-sickness, you might want to look away now.
In their latest attemptto lure movie-lovers back into the cinema, a Canadian firm has gone one step up from last year's 3-D craze - by inventing 4-D seats.
Available in 50 cinemas across the U.S., D-Box's electro-mechanical seats let movie-goers feel the actors' movements as they watch them on screen.
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In the hot seat: The expanding layer in the seats combines with three motors to move the viewer up, down and from side to side
The effects, carefully synchronised to the action, range from 'intelligent vibrations' to a popcorn-throwing jolt backwards if a character is punched on screen.
They can even re-create the sensation of freefall - at double the acceleration caused by gravity.
All the movements are controlled by a panel on the side of the seat, so squeamish viewers can turn down the intensity.
The seats first appeared last year, but are set to expand into even more cinemas this summer for blockbusters including the latest instalments of the Fast and Furious, Harry Potter and Pirates of the Caribbean franchises.
Not for the faint-hearted: But squeamish viewers can control their D-Box experience from a panel on the arm of their seat
Perfectly synchronised: The motion actuators, left, move the chairs according to a specially-programmed 'motion code'. The viewer controls the intensity, right
Engineers painstakingly go through each frame of the movie to create a 'motion code' which they lay alongside the soundtrack. It took them 600 hours to program the seats for the firm's latest venture, Fast Five.
This signal is sent to a D-cinema system box, which in turn transmits the code to each seat.
Of course, viewers will have to fork out a little extra to get the thrill of flying on a broomstick or being tossed across a heaving boat.
DBox adds an $8 premium to ticket prices, split between the company, the film studio and the cinema. If it's a 3-D screening, expect prices to be even higher.
4-D experience: The painstakingly-synchronised motion code is transmitted to the cinema system box, then on to each individual chair.
Painstaking: Engineers produce a 'motion code' synchronised to the natural movement of 'anyone and anything' in the film and lay it alongside the soundtrack
It's the latest development in an ongoing battle to create a cinema experience which can't be replicated at home - and which moviegoers will pay more for.