The visitor experience, a more intense form of the normal sense of presence, emphasizes the deep belief of personal contact with an extraterrestrial (or religious) entity. Phenomenological details of visitor experiences are expected to reflect the functions of deep temporal lobe structures; common details involve cosmic meaningfulness, vestibular experiences, flickering, complex visual sensations and alimentary references. After intense experiences, interictal-like behaviors similar to religious conversions (widening affect, sense of personal, desire to spread the word, concern about Man's destiny) emerge. Normal people who are prone to these experiences show frequent temporal lobe signs and specific personality characteristics that include enhanced creativity, suggestibility, mild hypomania, anxiety, and emotional lability. Learning histories that encourage the use of right temporal lobe functions for the consolidation of memory, such as compartmentalization of beliefs or repression due to early sexual abuse, predispose to intense visitor experiences. The most frequent precipitants are psychological depression, personal (existential) stress and proximal exposure to the focal tectonic strain fields that accompany luminous phenomena. Possible neuropsychological mechanisms are discussed.