ASSAP: Paranormal Research
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by Maurice Townsend

This article originally appeared in Anomaly 27

Recently there has been an explosion in the use of instrumentation on paranormal investigations. It is now quite usual for an investigation to involve the use of such things as infra-red cameras, digital thermometers and electric or magnetic field meters. But are there any problems with this new widespread use of electronic equipment?

Already the use of instruments is giving rise to new ideas, new theories and even claims for new paranormal phenomena. In the normal course of events this could only be welcomed. But what if some of these ideas actually result from lack of understanding of what the instruments are measuring? We would be in danger of going down more blind alleys, which is the last thing our subject needs right now. That is what this article is designed to forestall.

Many of the physical quantities now being routinely measured on investigations are little understood by non-scientists. As an illustration of how complicated these things can be, I will concentrate on one particularly popular area in investigation: electromagnetic field measurement. This example can be generalised to other areas as a general approach to the whole subject. Hopefully it will lead investigators, particularly less experienced ones, to profit from the use of instrumentation while avoiding the pitfalls.

Why use instruments?

For over a century paranormal phenomena have been studied more or less scientifically. And yet there are still many scientists, not to mention a large section of the general public, who do not believe such phenomena even exist. Clearly the phenomena are highly elusive. But still the general public report anomalies and still they cry out for explanation.

On the defensive for so long, many investigators content themselves with ‘proving’ that something paranormal has occurred in a case they are researching. They do this by proving that something ‘cannot have happened by any known normal means’. This rather negative process is always open to the problem that someone will one day discover just such a ‘normal means’ to retrospectively explain the case. What is even worse, such an investigative process makes no great attempt to find out how paranormal phenomena might actually work.

The trouble with most cases is that they are based purely on the evidence of what someone witnessed. We know enough about the unreliability of witnesses to realise it is difficult to build a solid theory on such evidence. People are sadly, for a variety of reasons, not reliable recorders of their surroundings. What is really needed is objective, corroboratory evidence.

This is where instrumentation comes in. It is one thing for someone to claim they saw a ghost. It is quite another for them to produce a photograph of one. While people are subject to innumerable influences, both physical and mental, that are still barely understood, a camera is a known quantity. We know its capabilities and its limitations. Also, a photographic negative can be studied at leisure after the event. Someone’s experience can only be accessed through their, often faulty and changing, memory, which cannot (yet) be put into a laboratory and analysed.

There is another important limitation to witnesses: they only have (arguably) five senses. Instrumentation can probe into all sorts of environmental influences that we, as humans, cannot detect. There is the whole of the electromagnetic spectrum, infra- and ultrasound, radioactivity, gases in the atmosphere, magnetic and electric fields, etc.

These environmental influences are important because they might:

a) be the cause of some paranormal phenomena

b) be misidentified by witnesses as paranormal

c) cause witnesses to hallucinate ‘paranormal’ phenomena

d) actually be produced BY paranormal phenomena

The last point is not often considered by researchers. For instance, some people think that poltergeist phenomena are produced by people somehow causing physical changes to their environment. Such changes cannot be readily explained by current physical theories. However, one commonly observed factor in physical processes is that they are rarely, if ever, 100% efficient (eg. a light bulb produces a lot of heat as well as light). If a paranormal phenomenon is capable of teleporting an object (such as an apport), which would require a lot of energy, it might result in an accompanying burst of ‘waste’ electromagnetic radiation. This would be a byproduct of the main process, like the waste heat from power stations. If such phenomena really occur, we could try to detect any ‘waste’ radiation that might accompany them.

So, what are the problems?

From the previous section I hope it is clear that, in terms of verifying and possibly explaining paranormal phenomena, instrumentation brings enormous advantages to investigations. Inevitably, though, there are problems. It has, for instance, been noted that introducing instrumentation to an allegedly haunted location seems to dampen down the phenomenon (which is worthy of research in itself). Unfortunately it lends itself only too readily to the sceptical argument that ‘people who are faking are less likely to do so if they think they will be caught by instruments’. While such things doubtless happen occasionally, on vigils often the only people present are investigators, who have nothing to gain from faking phenomena.

Far more serious than phenomena being ‘dampened down’ is the problem of misunderstanding the equipment itself. Few investigators are likely to be trained scientists and therefore cannot be expected to understand the limitations and proper use of their instruments or even necessarily what they are measuring. It is this gap in understanding that is at the root of the biggest potential problem with instrumentation. It could lead to unjustified claims of explanations for paranormal phenomena or even ‘new’ anomalies. Luckily there is a cure to this problem - a proper understanding of the instruments and the quantities they measure.

Understanding what you’re measuring

Unfortunately, it is necessary to have some idea of what you are measuring before you can decide what is normal and what abnormal. In the case of electromagnetic (EM) radiation it all starts with the humble electron. This is the particle that orbits atomic nuclei to form atoms. When allowed to flow freely, as in electrical conductors such as metals (where outer electrons are only loosely bound to their atoms), they produce an electric current. Such electric currents produce a magnetic field (eg. there will be one around a mains cable).

When two objects are brought together and then separated, temporary molecular bonds are formed and then broken. This process leaves more electrons on one object than the other. This produces static electricity. The excess (or deficit) of electrons gives rise to electrostatic fields (ie. constant fields which do not vary in strength). These fields produce a force that can move very light objects that are also charged (eg. small bits of tissue paper). Such electrostatic fields cannot move heavier objects, because when their strength reaches a relatively low level (3000kV/m) the surrounding air is broken down and becomes conducting, producing a spark which discharges the field. Such sparking produces ozone with its characteristic smell.

Electrons also give rise to static magnetic fields. When electrons in certain materials ‘align’ they produce a strong static magnetic field. The best known example of this is iron (and some alloys such as steel) which can form permanent magnets. The Earth has a static magnetic field produced by processes deep within its core. The effect is the same as a weak permanent magnet. Though generally stable, the Earth’s magnetic field does vary, particularly during electromagnetic ‘storms’ (when unusually high numbers of energetic particles are spat out by the Sun). Static magnetic fields produce a force that can move objects. Unlike electrostatic fields, there is no limit on how strong static magnetic fields can get (though strong fields are extremely rare in the natural environment). Their effect on other materials varies hugely. Iron and its alloys are affected strongly, whereas most other common materials are not.

Both static electric and magnetic fields produce a force that can move objects in a particular direction characteristic of the field. This gives rise to the concept that an EM field has a direction, as well as a strength. It is what makes compasses point north. So if you are studying static EM fields you need to measure both strength and direction at any given point in space (and ideally plot both on a plan). Static fields, whether electric or magnetic, are sometimes collectively referred to as DC. This, confusingly, stands for direct current, a reference to how they might be produced.

When electrons move (eg. in electrical conductors) things really get interesting. The motion of the electron gives rise to a magnetic field. Similarly, a conductor moving in the field of a permanent magnet will induce electrons to move inside it, so giving rise to an electric current (as happens in an electric generator). Such varying or moving electric or magnetic fields are sometimes collectively described as AC (for ‘alternating current’ - a reference to the equipment that commonly produces them).

It is important to note, though, that moving fields cannot usually move objects. If you think about it, it is obvious. Imagine a small magnet in a magnetic field that is changing direction five times a second. The magnet will try to move in opposite directions five times in a second. It is not likely to get very far. When you take inertia into account, it is unlikely to move at all.

By varying electromagnetic fields you introduce another variable to record - frequency. This is measured in Hz (‘times per second’). This is the number of times a field reverses direction per second. As this frequency increases, the fields behave less and less like fields (with force and direction) and more and more like waves (with no force and much greater range). This is electromagnetic radiation. Over about 100kHz radiation predominates and the waves are known as radio waves. At higher frequencies still radiation changes characteristics again to become such things as light, X-rays or gamma rays.

This brief discussion is, of course, a highly superficial summary. It is merely intended to give instrument users a flavour of the complexity of the physical quantities they are studying (without even considering such things as field gradients or polarisation). It would certainly benefit anyone using electromagnetic detectors to read up these subjects in advance of going into the field.

Measuring Varying (AC) Fields

Most commercially available electromagnetic detectors are aimed at the ‘EM field pollution’ market. They are typically designed to detect sources of electromagnetic fields (that some scientists believe could affect health) in domestic and commercial premises. Most are sensitive to 50-60Hz fields typical of mains electricity supplies. Others are often designed to look for microwaves (eg. from cellphones and leaky microwave ovens) or for inadvertent radio emissions from electronic devices (such as PCs). Unfortunately, it is not possible to design instruments to detect EM over the whole, or even a large chunk, of the entire frequency range.

There is an immediate problem here. All of the frequency ranges mentioned above are most often produced artificially. There are very few natural sources of such frequencies. For radio and microwaves the main natural sources, from space and the upper atmosphere, are extremely weak. There are some natural sources for 50-60Hz waves (known as ELF - extremely low frequency), such as lightning, but they are few and far between. Before the advent of mains electricity these frequencies were very quiet. If you take an ELF meter into the countryside or even a town park you will not record much (except near overhead lines or during a thunder storm)! But many phenomena we are investigating have been reported for centuries, long before such artificial sources of EM radiation. It is therefore unlikely that such frequencies are involved in producing them. It is, of course, possible that new kinds of anomalous phenomena may be associated with artificial sources of EM radiation. But certainly ghosts, poltergeists and the like long predate electricity generation.

Having said that, it is still worth owning one of these ‘EM pollution’ instruments as it could provide a natural explanation for a phenomenon. For instance, modern artificial fields might conceivably produce phenomena that resemble paranormal phenomena. Their detection could thus point to possible natural explanations for a reported phenomenon.

There are, however, further things to bear in mind when taking readings with these instruments. There is, for instance, the question of whether readings are what they seem. Remember that ‘EM pollution’ detectors are often most sensitive to 50-60Hz electric or magnetic fields. However, most instruments will also be sensitive, to a lesser degree, to other nearby frequencies. So if you got a reading of 5 microteslas on a meter, it could be indeed be 5 microteslas at just 60Hz. But it might be 10 microteslas at 30Hz which, because the meter is less sensitive at that frequency, it reports as 5 microteslas. Most likely of all it will represent an average over a broad range of frequencies. So it is difficult to say exactly what such a reading of 5 microteslas represents precisely.

Ideally, for varying fields, you should use a detector that incorporates some kind of spectrum analyser. It would then be possible to produce a graph of field strengths against frequency. Such an instrument would be really worthwhile! However, it would not be cheap. Alternatively, you could always build something from reasonably cheap components if you have a good practical understanding of electronics.

Measuring Static (DC) Fields

You can get detectors to measure static fields, though they tend to be expensive. Static fields are definitely produced naturally and so might indeed be associated with long-reported anomalous phenomena. The most pervasive source of magnetic fields is the Earth’s field. It tends to be fairly constant at any particular place (except during solar storms). Other significant natural sources of static magnetic fields include certain minerals, such as magnetite. There are many natural sources of static electric fields. Just rubbing two objects together can build up charges. We are all familiar with getting minor shocks when touching metal objects. Lightning is also a natural source of static electric fields.

If you have trouble getting hold of cheap static electric and magnetic field detectors, you can at least use a humble compass to indicate the presence and direction of static magnetic fields. If, when you walk across a room in a straight line, the compass needle rotates it will indicate the presence of a local magnetic source. Unfortunately it will give you no idea of the strength of the field. A strong static electric field may be indicated by a smell of ozone (though this is more likely to be produced by malfunctioning electrical equipment). Again, a cheap meter could be built from commercially available components.

Apart from magnitude, static electric and magnetic fields also have direction. This is more difficult to measure than magnitude. It would determine which way an object might move if subjected to a strong field. You can measure the direction of static magnetic fields with a simple compass.

I have mentioned objects (particularly iron-based alloys such as steel - not most iron compounds, incidentally, as the electrons are arranged differently in them) being moved by magnetic fields. No doubt some people will immediately think of objects flying around in poltergeist cases. Before you get carried away with the idea of static magnetic fields causing poltergeist phenomena, I ought to put the idea into perspective. The strength of fields required to move even iron objects is far higher than would occur in most natural or domestic situations. To levitate even light (of the order of grammes) non-iron based objects (poltergeists don’t seem to mind what their target objects are made of) takes static magnetic fields in the order of 10 or more tesla. That is a huge field strength that would normally only be seen inside a specialist laboratory (a magnetic resonance imaging scanner, for instance, works at a few tesla). By comparison, the magnet in a typical loudspeaker might be a few thousand microteslas and the Earth’s magnetic field 50 microteslas. Incidentally, if there were such a huge magnetic field loose in a house it would have a few other noticeable effects, eg. wiping magnetic tapes and credit cards, ruining television sets and watches, make electronic switches (based on relays) stick and probably cause severe damage to the electrical supply equipment in the building.

What is normal?

Before going into a real-life investigation it is important that you get to know your instrument. In particular you should satisfy yourself that it is correctly calibrated (ie. giving accurate readings) and that you know what to expect in ‘normal’ situations (ie. where no anomalous phenomena have ever been reported).

For calibration you usually have to rely on the manufacturer. However, if you can get hold of ‘standard’ comparisons (ie. sources of known field strength) it should give a reasonable level of confidence. Many meters will come with examples of the sort of readings you can expect in domestic situations. If you are getting something wildly different you may need to return the meter to the manufacturer for checking or replacement.

If your instrument does not show any figures but only the ‘presence’ of fields (eg. by way of a light being on), I’m afraid it is of limited use in investigations. Such instruments are designed to see if fields exceed a particular threshold. Unfortunately, even if you know what this threshold is, you cannot tell if the field is twice or three times that value or indeed half as much.

One important tip is that most electromagnetic meters are sensitive (even AC field ones) to static electricity and YOU are a potent source. Therefore, put the meter down and don’t touch it for, say, 10 seconds. The reading should then stabilize and will probably be a lot less than when you are carrying the equipment around. This will be a much truer reading, and you should always use meters in this way.

Having calibrated your equipment, you must now work out what are ‘normal’ readings. Only with such knowledge can you possibly judge what is ‘abnormal’. While it is possible to find out typical values from various sources (try the world wide web) it is best to find out for yourself with your own instrument. This is particularly important with AC fields. Different instruments have different frequency responses. Most standard tables of field strengths produced by mains appliances or overhead cables are for 50 or 60Hz. Your instrument may be sensitive to a much wider range of frequencies. In addition, non-mains-powered electrical equipment may produce stray fields at different frequencies. How do you know what to expect from, for example, portable (battery-powered) appliances, transport vehicles or transmitting equipment? Some equipment, such as computers, can transmit high frequency waves unintentionally. The best way to find out is to measure it for yourself.

A particularly useful technique is to check similar locations ‘after the event’. For instance, if you go on a vigil to a pub and find a potent source of AC fields in the cellar, it might seem highly significant (especially if a ghost has been seen there). But might not most pub cellars have similar readings? There are often pumps and other heavy electrical equipment in pub cellars. So try to go to a few others, not known to be haunted, and see if they give similar readings.

When on an investigation it is, of course, most important to identify the sources of any electromagnetic fields. Usually this can be done visually (simply looking for electrical equipment). Sources may not, however, always be obvious. They could be behind walls, eg. mains cabling which emits magnetic fields. If you cannot trace any source internal to a building you might try switching off the power to a room, or even the whole building, to see if the field drops. I hasten to say this should only be done with the permission of the building owner or manager. Even if they agree you should consider if switching off all the power might disrupt permanently powered equipment, timeswitches or machines sensitive to powercuts, such as computers. If you CAN get the mains switched off, you might be able to locate any external sources of electromagnetic fields.

As a very general guide, here are some examples of the sorts of fields you might expect. Many appliances produce 50/60Hz AC fields, as you might expect. As a result a typical domestic room, away from appliances, may have up to 0.4 microtesla AC magnetic fields in it and maybe a few tens of volts per metre AC electric. Obviously, near appliances the readings can be much higher. Fields drop off with increasing distance from sources according to the ‘inverse square rule’. This basically means they drop off rapidly with increasing distance. Very close to an appliance the readings can be quite high. At a distance of 15cm some appliances may yield as much as 100 microtesla (magnetic), though less than 10 is more typical. At a metre away many appliances will be undetectable. Electric readings may rise to a 1000 volt/metre close to some appliances, though much less further away.

Static magnetic fields are rarer than varying ones in domestic situations. The Earth’s magnetic field will be present (unless shielded somehow - eg. by metal in walls) but it is very weak, between 30 (at the equator) and 60 (at the poles) microteslas. Various household devices have permanent magnets in them, eg. loudspeakers or anything with a motor of some sort in it. Some appliances also contain electromagnets (eg. as relays) that produce static fields when activated. The magnets in these devices will be much stronger than the Earth’s magnetic field but still usually far too weak to, say, move even a nearby light iron object. Typical values for such devices might be a few thousand microteslas.

Static electric fields in domestic situations are usually caused by friction. It can depend heavily on the type of materials used in the room. A typical room might produce up to around 5V/m. If a thunderstorm was going on outside it might be up to 100V/m.

Using meters outside tends to give very low (or nil) readings due to the low density of natural or artificial sources of EM. At a distance of 15m a 500kV overhead power line only yields typically between 3 and 6 microteslas (magnetic). Interestingly, if you live near overheadpower lines you are likely to receive higher field exposure from your domestic appliances than from the power lines (though, of course, most appliances are only used for short periods whereas power lines are always on).


Though nothing to do with electromagnetic fields, I must mention infrasound. This is because it has recently been discovered (see Journal of the Society of Psychical Research, volume 64.3, number 860, July 2000) that infrasound with a frequency of 19Hz can induce feelings anxiety and dizziness. If this frequency is present at significant levels (eg. as a resonating standing wave) it could produce reports of hauntings (eg. feelings of a ‘presence’). This is certainly something we should look for on investigations.


This article merely scratches the surface of the issues involved in using instrumentation on investigations. While it is not the intention to discourage anyone from using instrumentation, I hope the article has illustrated the complexity of the subject. I hope it will make people think a little before making claims based purely on apparently abnormal instrument readings.


The units used in electromagnetic field measurement can be confusing. Firstly, if the field is varying you will need to specify the frequency being measured in Hz (ie. per second). Electric field strength, whether varying or not, is measured in volts per metre or V/m. Magnetic field strength (strictly speaking, flux density) is usually quoted nowadays in microteslas. Unfortunately, many people use the older unit of the milligauss, which causes endless confusion. Please stick to microteslas if you can. To convert, 10 milligauss = 1 microtesla. Incidentally, the units gauss and tesla are not commonly used as they are both very large by everyday standards.