oh derrrrr.
that was a stupid question for me to ask wasn't it? let me assure you it was. vertigo as you may know is the feeling of disproportion when for example at the top of some stairs. instead of seeing it as it is and the descent, people who suffer it, see it as warped and not accurate - almost 2d. it causes them to be overly cautious from having no judgement on the distance etc.
curious how these things work, i think.