Perception is just an experience -- and as such antecedes any judgment of "rightness" or "wrongness;" "truth" or "falsehood." Perception just is. (In a similar way, a moss-covered rock is neither true nor false; it is only what it is -- a moss-covered rock.) Evaluating something is technically an experience, too, in that it is the movement of atoms. But it is a very different kind of experience than perception. Perception involves an experience between the body and an external object; evaluation is a self-generative experience which occurs solely within the body. In one sense, an evaluation "just is" the same way that a perception "just is;" both consist of atoms moving in a particular way. But in another sense, we evaluate ABOUT something else, and thus can reach correct or incorrect evaluations, about that other thing. (I can correctly evaluate "sour-ness" to be an event between my body and a lemon, or I can incorrectly evaluate "sour-ness" to itself be an existing entity.) The standard for my evaluations is the actual nature of things.