The Skeptics Society & Skeptic magazine

Shermer and Alderson-Day discuss the psychologist’s journey to understand the phenomenon of sensed-presence: the disturbing feeling that someone or something is there when we are alone. Using contemporary psychology, psychiatry, neuroscience, and philosophy, Alderson-Day attempts to understand how this experience is possible. Is it a hallucination, a change in the brain, or something else? The journey to understand takes us to meet explorers, mediums, and robots, and step through real, imagined, and virtual worlds.

In parts of Asia and the Orient entire regions are occasionally overwhelmed by terror-stricken men who believe that their penises are shriveling up or retracting into their bodies. Episodes can endure for weeks or months and affect thousands. Psychiatrists are divided as to the cause of these imaginary scares. Some believe that it is a form of group psychosis triggered by stress, while others view it as mass hysteria. How can groups of people come to believe that their sex…