Inversion glasses, which invert the visual field along the left-right or up-down axes, have been used to investigate the link between action and perception for at least a 100 years (Stratton 1897). As I mentioned in my last post, they really mess up perception by disrupting the usual links between motor commands, optic flow, eye movements and vestibular inputs. Here’s a choice quote from a subject mentioned in Kohler (1951):

As I begin to move and walk about, the room begins to move too. What I am experiencing are the apparent movements of the objects around me. As I approach one of them, it seems to move to the right. I reach out and touch — air: my arm completely missed it, passed to the left of it… Even more peculair are the relative changes inside the room. When I move my head (vertically or horizontally), not a single point remains stationary in relation to another point. If a certain point moves along with me in the visual field, then some other point will infallibly move in the opposite direction, as if indicating in no uncertain terms that it is not the least bit bound by what the other points appear to be doing at the time. The world I am in seems to have become a total chaos of continuously changing distances, direction, movements, and Gestalten.

I ordered some up-down inversion glasses and got them today. They’re plastic goggles with an embedded prism that inverts up and down. Now, mind you, these aren’t research quality glasses, the field of view is pretty limited, but they’re still quite interesting to play around with. Here’s a video me trying on the goggles (thanks to Farhan for taking the video):

Wearing them and trying to do anything useful is a real mindfuck. I find that walking in a straight line is possible, but changing one’s direction is utterly confusing. I frequently get vestibular illusions (something akin to vertigo) while wearing them, and sometimes I have to stop because I feel sick to the stomach. Going up stairs is pretty scary. I haven’t worn them long enough to say that I’m used to walking around with them, but if I take them off after 5 minutes I really start to notice my up-down saccades, which is a really disorienting feeling.

It’s a nice prop for a vision lab; also quite useful for explaining your research to your date while not boring the hell out of her. Get some.