ESP is considered a perception of information about events beyond what may be discerned through the five physical senses or deduced from past experience or knowledge. This release consists of cross references to ESP found in FBI files from 1957 to 1960. Several of the documents concern William Foos, a proponent of ESP. Others concern claims that ESP could be used in espionage investigations. The FBI found no scientific support for this or other claims and did not pursue the matters raised in these references.