Carl Sagan (1977) and Barbara Honegger (1983) wrote that the OBE experience may be based on a rebirth fantasy or reliving of the birth process based on reports of tunnel-like passageways and a cord-like connection by some OBErs which they compared to an umbilical cord. Susan Blackmore (1978) came to the conclusion that the OBE is a hallucinatory fantasy as it has the characteristics of imaginary perceptions, perceptual distortions and fantasy-like perceptions of the self (such as having no body). Ronald Siegel (1980) also wrote that OBEs are hallucinatory fantasies.