The waterfall illusion can be transferred between vision and touch

If you look at a waterfall for about 30 seconds, and then shift your gaze to a nearby stationary object, such as a rock or a tree, that object will seem to drift slowly upwards. This well known optical illusion demonstrates a phenomenon called the motion after-effect, which is thought to occur as a result of adaptation - the brain compensates for movement in one direction, causing us to momentarily perceive a stationary objects to be moving in the other.

Although illusory motion can also be induced in the sense of touch, the brain is thought to process visual and tactile motion separately. But now researchers from MIT have found that not only can moving visual stimuli induce a tactile motion after-effect, but also that moving tactile stimuli can induce a visual motion after-effect. The findings, which are published in Current Biology, show that the senses of vision and touch are closely linked, and that each can influence the other.