Studying the sensory nervous system reveals a great deal about our sense of reality. Our respective experinces of the environment differ dramatically depending on, for example, how much light may be passing through the window we may be sitting under, as compared to someone else sitting in the relatively dark corner of the room. The image of our environment that is superimposed on to our retinas becomes one of our most informative methods of gathering pertinent information from the environment.
Someone who has poor eyesight may not experience the elation that I feel when the sky is perfectly clear and I can see that the flowers are beginning to bloom. This part of my reality may simply not exist because to this individual because they cannot percieve the signs of spring due to impaired sensory apparatus. >From what we have learned about the visual system in particular, I feel that reality is completely subjective, due to the extraordinary number of differences that we experience due to our interaction with the environments.
There's certainly a subjective element in any given person's idea of "reality", for the reasons you give (among others). And that's important. So too are some things we have yet to come to. A continual testing of one's idea of reality against additional input. By that device, one's "reality" can change, and perhaps become more "objective"? PG