Lateral skin deformation, or laterotactile stimulation as we now like to call it, was first described in (Hayward and Cruz-Hernandez, 2000). It consists of a tactile stimulation mode by which a traveling wave of lateral skin deformation can induce the sensation of a moving feature under the fingertip.

The principle is best explained with a simple demo, which requires a plastic comb and a pen. Take a look at the following movie to understand - or even better to feel - how laterotactile stimulation can produce the illusion that a small dot is moving under the index fingertip, even in the absence of any normal skin indentation.