Let's look at this [question of observation] at a down-home level. I would insist that you cannot observe edible things on banana trees unless you had some experience that would lead you to construe what you see as safe and nourishing. This is why a city slicker who is lost in the forest can starve to death because he does not observe what is out there as food. He does not thave the requisite experience and background to categorize things in useful ways and to see that he is surrounded by edible, useful material.
Our experiences, then, are not just our sensations. Our experiences, our observations, are the way that we construe our sensations, and the way that we construe them is a product of all our experiences, and of a great many other things as well. So one could claim, then -- and many people have claimed -- that our observations are relative to the conceptual apparatus, and the prior experience, and all of the other things that come into play, that enable us to construe our sensations the way we do and arrive at the observations that we arrive at.