Joe Nickell of the Committee for Skeptical Inquiry, wrote that there was no credible scientific evidence that any location was inhabited by spirits of the dead.^[66] Limitations of human perception and ordinary physical explanations can account for ghost sightings; for example, air pressure changes in a home causing doors to slam, or lights from a passing car reflected through a window at night. Pareidolia, an innate tendency to recognize patterns in random perceptions, is what some skeptics believe causes people to believe that they have 'seen ghosts'.^[67] Reports of ghosts "seen out of the corner of the eye" may be accounted for by the sensitivity of human peripheral vision. According to Nickell, peripheral vision can easily mislead, especially late at night when the brain is tired and more likely to misinterpret sights and sounds."^[68]

Some researchers, such as Michael Persinger of Laurentian University, Canada, have speculated that changes in geomagnetic fields (created, e.g., by tectonic stresses in the Earth's crust or solar activity) could stimulate the brain's temporal lobes and produce many of the experiences associated with hauntings.^[69] Sound is thought to be another cause of supposed sightings. Richard Lord and Richard Wiseman have concluded that infrasound can cause humans to experience bizarre feelings in a room, such as anxiety, extreme sorrow, a feeling of being watched, or even the chills.^[70] Carbon monoxide poisoning, which can cause changes in perception of the visual and auditory systems,^[71] was speculated upon as a possible explanation for haunted houses as early as 1921.