4D is nothing but a scam. We cannot perceive 4D, but there are lots of attractions dubbed 4D. These attractions usually make use of the chairs and theater themselves moving to give you a PHYSICAL feel of what you're watching, instead of just a visual one (ie, changing temperature, blowing wind, moving seats, etc).
At Disney on some Lilo and Stitch ride, they made it smell so bad when Stitch burped QQ
But yeah 4D is a scam basically. Lot of it is stupid and doesn't make it feel any more like your there.