Abstract: "Ss (subjects) who reported UFO experiences were divided into those whose experiences were non intense (e.g., seeing lights and shapes in the sky) and those whose experiences were intense (e.g., seeing and communicating with aliens or missing time). On a battery of objective tests Ss in these 2 groups did not score as more psychopathological, less intelligent, or more fantasy prone and hypnotizable than a community comparison group or a student comparison group. However, Ss in the UFO groups believed more strongly in space alien visitation than did comparison Ss. The UFO experiences of Ss in the intense group were more frequently sleep-related than the experiences of Ss in the non-intense group. Among the combined UFO Ss, intensity of UFO experiences correlated significantly with inventories that assessed proneness toward fantasy and unusual sensory experiences. Implications are discussed."
Spanos, Nicholas P., Patricia A. Cross, Kirby Dickson, and Susan D. DuBreuil. "Close Encounters: An Examination of UFO Experiences." Journal of Abnormal Psychology 102 (1993): 624-631.