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.