When I broke the radius bone in my right arm two months ago, I had no idea that I would begin another intense form of therapy. The bone did not heal quite right so I'm now engaged in hand therapy twice a week. At the first therapy session, the therapist asked me to place my arm, palm side down, on a table. Gingerly, I stretched out my arm on the table and felt something strange. Although to the eye, the table top appeared smooth, it felt like the surface actually bulged under my wrist. "Is this some kind of special hand therapy table?" I wondered. But, at the next session, I extended my arm, once again palm down, along a different part of the table and felt the same bulge. I thought this was really strange. How could the same bulge be in so many places on the table's surface? So, I took my uninjured left arm and stretched it, palm down, across the table. The table top felt flat under my left arm. Indeed, the surface was smooth and level; there were no bulges. Instead, a lot of new bone had grown near my right wrist, so the way my arm contacted the table's surface had changed. I had misinterpreted the new feel of my arm against the table as a bump in the table's surface rather than a change in my own body!
I think this sort of mistake happens fairly often. When I first learned to fuse images from my two eyes and see in 3D, I noticed that edges and borders around all objects appeared sharper and better defined. Upon first seeing this crisp new view, I concluded that the air around me was unusually clear and clean. It took several days before I realized that the change was due to improvements in my own vision and not to the quality of the air.
These experiences remind me of the enormous influence that our past experiences and our expectations have on our perception. When changes in our body cause external objects to appear or feel different, we may misinterpret our sensations and conclude that alterations have occurred in the environment or objects around us rather than in our own selves.