Mass hysteria is characterized by the rapid spread of conversion disorder, a condition involving the appearance of bodily complaints for which there is no organic basis. In such episodes, psychological distress is converted or channeled into physical symptoms. There are two common types: anxiety hysteria and motor hysteria. The former is of shorter duration, usually lasting a day, and is triggered by the sudden perception of a threatening agent, most commonly a strange odor. Symptoms typically include headache, dizziness, nausea, breathlessness, and general weakness. Motor hysteria is prevalent in intolerable social situations such as strict school and religious settings where discipline is excessive. Symptoms include trance-like states, melodramatic acts of rebellion known as histrionics, and what physicians term "psychomotor agitation" (whereby pent-up anxiety built up over long period results in disruptions to the nerves or neurons that send messages to the muscles, triggering temporary bouts of twitching, spasms, and shaking). Motor hysteria appears gradually over time and usually takes weeks or months to subside.Ghost hunters are most often affected by demopathic hysteria. Typically this involves the belief that something has followed them home from a ghost hunt although it can also include some symptoms typical of psychosomatic response.Bias:
Investigator Bias occurs when the interviewer is aware (not blinded) of the outcome variable. A non-blinded investigator may be more vigorous in searching for the exposure of interest. Bias can occur from both angles of ghost hunting, believer and nonbeliever. A good ghost hunter must walk a line between the two as to not contaminate his or her data with bias. Every possibility must be thoroughly considered before a determination is made to the nature of the phenomena. Bias is the most common reason why theories are rejected by the scientific community.The first organized body of researchers to band together and apply scientific techniques to the study of ghost phenomena was the Society for Psychical Research. Formed in 1882 by a group of distinguished Cambridge scholars, they immediately set about trying to formulate and prove theories on all subjects relating to the paranormal, including telekinesis and clairvoyance as well as haunting activity. Unfortunately, many of the early SPR members seemed to be too gullible, wanting desperately to believe the claims of many so-called mediums and psychics. This led to the downfall of many researchers, with the credibility of the SPR being severely damaged as a whole, when most of the charlatans who had been declared genuine by the Society later were shown to be fraudulent.Ironically, it was one of the SPR's own founding members, Harry H. Price, who debunked so many of the supposed psychics. These included psychics who Price himself had originally declared to be genuine. It was bias that doomed his organization.