|Part of a series of articles on the paranormal|
A ghost hunter taking a reading with an EMF meter.
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Ghost hunting is a fringe pseudoscience wherein its few adherents visit and investigate locations that are reported to be haunted by ghosts. Typically, a ghost hunting team will attempt to collect "evidence" that they see as supportive of paranormal activity. Ghost hunters often use a variety of electronic devices: the EMF meter; digital thermometer; handheld and static digital video cameras, such as thermographic (or infrared) and night vision; digital audio recorder; and computer.
Traditional techniques such as conducting interviews and researching the history of a site are also employed. Some ghost hunters refer to themselves as a paranormal investigator. Ghost hunting has been heavily criticized for its total absence of scientific method; no scientific body has been able to confirm the existence of ghosts. Ghost hunting is considered a pseudoscience by a vast majority of educators, academics, science writers, and sceptics. In contrast, the concept of the ghost and narratives featuring ghosts are a topic of academic study in folkloristics.
Paranormal research dates back to the 19th century, with organisations such as the Society for Psychical Research investigating spiritual matters. Psychic researcher Harry Price published his Confessions of a Ghost-Hunter in 1936.
Ghost hunting was popularised in the 2000s by television series such as Most Haunted and Ghost Hunters, combined with the increasing availability of high-tech equipment. The Atlantic Paranormal Society reported a doubling in their membership in the late 2000s, attributing this to the television programs. Despite its lack of acceptance in academic circles, the popularity of ghost-hunting reality TV shows has influenced a number of individuals to take up the pursuit.
Small businesses offering ghost-hunting equipment and paranormal investigation services increased in the early 2000s. Many offer electromagnetic field (EMF) meters, infrared motion sensors and devices billed as "ghost detectors". The paranormal boom is such that some small ghost-hunting related businesses are enjoying increased profits through podcast and web site advertising, books, DVDs, videos and other commercial enterprises.
One ghost-hunting group reports that the number of people taking its tours has tripled, jumping from about 600 in 2006 to 1,800 in 2008. Another says its membership has doubled. Others point to increased traffic on their websites and message boards as an indication that ghost hunting is becoming more accepted. Participants say that ghost hunting allows them to enjoy the friendship of like-minded people and actively pursue their interest in the paranormal. James Willis, founder of The Ghosts of Ohio group, says that his membership has grown to 30 members since it was founded in 1999 and includes both true believers and total skeptics. Willis says his group is "looking for answers, one way or another" and that skepticism is a prerequisite for those who desire to be "taken seriously in this field."
Author John Potts says that the present day pursuit of "amateur ghost hunting" can be traced back to the Spiritualist era and early organizations founded to investigate paranormal phenomena, like London's The Ghost Club and the Society for Psychical Research, but that it is unrelated to academic parapsychology. Potts writes that modern ghost hunting groups ignore the scientific method and instead follow a form of "techno-mysticism".
The popularity of ghost hunting has led to some injuries. Unaware that a "spooky home" in Worthington, Ohio was occupied, a group of teenagers stepped on the edge of the property to explore. The homeowner fired on the teenagers' automobile as they were leaving, seriously injuring one. A woman hunting for ghosts was killed in a fall from a University of Toronto building.
An offshoot of ghost hunting is the commercial ghost tour conducted by a local guide or tour operator who is often a member of a local ghost-hunting or paranormal investigation group. Since both the tour operators and owners of the reportedly haunted properties share profits of such enterprises (admissions typically range between $50 and $100 per person), some believe the claims of hauntings are exaggerated or fabricated in order to increase attendance. The city of Savannah, Georgia is said to be the American city with the most ghost tours, having more than 31 as of 2003.
According to a survey conducted in October 2008 by the Associated Press and Ipsos, 34 percent of Americans say they believe in the existence of ghosts. Moreover, a Gallup poll conducted on June 6-8, 2005 showed that one-third (32%) of Americans believe that ghosts exist, with belief declining with age. Having surveyed three countries (the United States, Canada, and Great Britain), the poll also mentioned that more people believe in haunted houses than any of the other paranormal items tested, with 37% of Americans, 28% of Canadians, and 40% of Britons believing.
In 2002, the National Science Foundation identified haunted houses, ghosts, and communication with the dead among pseudoscientific beliefs.
Many ghost-hunting groups say they find evidence of something they can't explain through scientific or natural means, yet critics question ghost-hunting's methodology, particularly its use of instrumentation, as there is no scientifically proven link between the existence of ghosts and cold spots or electromagnetic fields. According to skeptical investigator Joe Nickell, the typical ghost hunter is practicing pseudoscience. Nickell says that ghost hunters often arm themselves with EMF meters, thermometers that can identify cold spots, and wireless microphones that eliminate background noise, pointing out the equipment being used to try to detect ghosts is not designed for the job. "The least likely explanation for any given reading is it is a ghost," maintains Nickell. Orbs of light that show up on photos, he says, are often particles of dust or moisture. "Voices" picked up by tape recorders can be radio signals or noise from the recorder and EMF detectors can be set off by faulty wiring or microwave towers.
According to investigator Benjamin Radford most ghost hunting groups including The Atlantic Paranormal Society make many methodological mistakes. "After watching episodes of Ghost Hunters and other similar programs, it quickly becomes clear to anyone with a background in science that the methods used are both illogical and unscientific". Anyone can be a ghost investigator, "failing to consider alternative explanations for anomalous ... phenomena", considering emotions and feelings as "evidence of ghostly encounters". "Improper and unscientific investigation methods" for example "using unproven tools and equipment", "sampling errors", "ineffectively using recording devices" and "focusing on the history of the location...and not the phenomena". In his article for Skeptical Inquirer Magazine Radford concludes that ghost hunters should care about doing a truly scientific investigation "I believe that if ghosts exist, they are important and deserve to be taken seriously. Most of the efforts to investigate ghosts so far have been badly flawed and unscientific --- and, not surprisingly, fruitless." 
Although some ghost hunters believe orbs are of supernatural origin, skeptic Brian Dunning says that they are usually particles of dust that are reflected by light when a picture is taken, sometimes it may be bugs or water droplets. He contends that "there are no plausible hypotheses that describe the mechanism by which a person who dies will become a hovering ball of light that appears on film but is invisible to the eye." He does not believe there is any science behind these beliefs; if there were then there would be some kind of discussion of who, what and why this can happen. In his investigations he can not find any "plausible hypothesis" that orbs are anything paranormal.
Science writer Sharon Hill reviewed over 1,000 "amateur research and investigation groups" (ARIGs), writing that "879 identified with the category of "ghosts". Hill reports that many groups used the terms "science" or "scientific" when describing themselves; however "they overwhelmingly display neither understanding of nor adherence to scientific norms".
"ARIGs often promote their paranormalist viewpoint as scientifically based, especially in community presentations or lectures at educational facilities. While scientifically minded observers can readily spot the anemic and shoddy scholarship of popular paranormal investigation, the public, unaware of the fundamental errors ARIGs make, can be persuaded by jargon and "sciencey" symbols."
Hill sees the supernatural bias of such groups as an indication of how "far removed ARIG participants really are from the established scientific community".
Ghost hunters use a variety of techniques and tools to investigate alleged paranormal activity. While there is no universal acceptance among ghost hunters of the following methodologies, a number of these are commonly used by ghost hunting groups.
According to ghost hunters, a cold spot is an area of localized coldness or a sudden decrease in ambient temperature. Many ghost hunters use digital thermometers or heat sensing devices to measure such temperature changes. Believers claim that cold spots are an indicator of paranormal or spirit activity in the area; however there are many natural explanations for rapid temperature variations within structures, and there is no scientifically confirmed evidence that spirit entities exist or can affect air temperatures.