4D? Fourth dimension is time. I guess that would potentially be good for input lag, send the picture back to before it was sent lol. 3D screens aren't really worth it, but it depends on what context you are talking about. Computer, TV etc?
Or 4d could mean they add to where us Humans can feel what is happening in a particular scene in a movie or a cut scene in a game such as water being splashed on them or smelling a smell form the movie. I have heard about this happening in 4D movies.
