 Such difficulties of interpretation are much less obvious in the case of written reports by ostensibly normal subjects, in good health and not medicated at the time of the experience.As mentioned above, at least some of the apparitional experiences reported by normal subjects appear to mimic normal perception to such a degree that the subject is deceived into thinking that what they are experiencing actually is normal perception.Similar close mimicking of normal perception is reported by some of the subjects of a lucid dream and out-of-body experiences, which therefore pose similar problems for the theory of direct realism.