The third thought experiment makes use of inverted goggles. Scientists have devised special eyeglasses that invert up and down for the wearer. When you put them on, everything looks upside down. When subjects first put them on they can barely walk around without stumbling. But when subjects wear these goggles for a while, something surprising occurs. They adapt and become able to walk around as easily as before. When you ask them whether they adapted by re-inverting their visual field or whether they simply got used to walking around in an upside- down world, they can't say. So as in our beer-drinking case, either we simply do not have the special, infallible access to our qualia that would allow us to distinguish the two cases, or, perhaps, the way the world looks to us is actually a function of how we respond to the world—in which case qualia are not “intrinsic” properties of experience.