 According to one empiricist tradition, experience functions as a mirror, reflecting what is before the subject, without any manipulation by the subject’s mind. Given that experience is supposed to not be influenced by one’s theories or expectations, it is thereby supposed to be in an optimal position to confirm or disconfirm hypotheses about the world. According to a wide range of philosophers and scientists, such a picture of the nature of experience is mistaken, putting limitations on the ability of experience to justify belief. In the philosophy of science, the challenge has been put in terms of the “theory-dependence of observation”, and the implications thereof. In more recent epistemology and philosophy of mind, the challenge has been put in terms of “cognitive penetration” or “top-down” effects and the implications thereof.