The Trouble with Equipment: Are you Wasting your Time?
Dave Wood reviews why investigators use ‘ghost hunting equipment’ and whether we should bother. 
There seem to be two broad reasons why paranormal investigators use ‘ghost hunting equipment’. One reason is scientific, the other distinctly psuedo-scientific. Both clamber under the banner of ‘scientific enquiry’ whilst perhaps neither of them belong there.
Numerous website happily take the money of budding paranormal investigators for equipment they purport to ‘detect ghosts’. EMF meters, for example, are frequently sold as ‘ghost detectors’; an assertion accepted unchallenged by many. There are even supporting theories about the ‘electro-magnetic properties of ghosts’ based not on evidence but on pure speculation. To some, the use of EMF meters is to ‘scientifically’ track ghosts – but pseudo-scientifically wasting time might be a more accurate description.
So why do the more ‘scientific groups’, and indeed PSI as a group, carry EMF meters on investigations? Scientists have tested theories that natural electro-magnetic fields are in fact ‘experiencer influencing’. This means that EM fields in fact influence what an individual is experiencing at any one time. Taken in tandem with paranormal context and expectation, individuals may be attributing perfectly normal phenomena to ghostly goings-on.
So this theory seems to vindicate the scientific use of EMF meters. There are similar theories, although somewhat less scientifically verified, regards infrasound, temperature, humidity etc (and thereby justifying the use of carrying detectors).
The final hurdle, however, is that EMF meters do not detect experiencer-influencing EM fields with any degree of accuracy. EMF meters specialise in detecting wholly unnatural EM fields, such as those from electrical wiring. A EMF meter that actually detects what investigators are looking for could set you back a cool £8,000, a self build – and that’s before going on a course working out how to use it.
So why does PSI use EMF meters? PSI never rules out any enquiry without studying it properly. PSI is monitoring use of EMF meters on investigations for 18 months before drawing final conclusions on their use.