An Honest Starting Point
People arrive at this page wanting a yes or a no. It is better to explain at the outset what kind of answer is actually available.
If you suspect your partner of cheating, the question in your mind is simple: did they or didn't they? Many people assume a lie detector test can be asked exactly that. The Concealed Information Test cannot. It has no way to examine a general question about behaviour, because there is nothing specific in the question for the brain to recognise.
What a CIT can do is narrower and, in the right circumstances, more useful. If you have found something concrete, and your partner does not know you have found it, the test can show whether their brain treats that thing as familiar. A name they claim never to have heard. A bar they say they have never been to. A town they have no reason to know.
So the first thing to work out is not "do I want a test?" but "do I have a detail?". If you do, read on. If you do not, the section headed If You Have No Details sets out your options plainly.
How a CIT Applies to a Relationship Case
The method is the same as in any other case. Here is what it looks like in this one.
Suppose you have seen a message on a shared tablet from someone saved under the name "Carla", and separately you have noticed a card payment at a restaurant in Knutsford on a night your partner said they were working late. You have said nothing about either.
That gives two possible blocks. In the first, your partner sees a list of women's first names, one at a time: Carla among five others chosen to be equally common and equally unremarkable to them, plus one target name they are asked to press a key for. In the second, they see a list of Cheshire towns: Knutsford among five others, plus a target.
They are not asked whether they know a Carla. They are not asked whether they went to Knutsford. They simply watch names and press keys while an EEG cap records the response to each one. Every name is shown around thirty times. Afterwards, the analysis compares the brain's response to "Carla" with its response to the other names, and "Knutsford" with the other towns.
If "Carla" draws a clearly and consistently larger P300 than the alternatives, your partner's brain is treating that name as significant. If it sits level with the others, there is no sign that it means anything to them. The same applies to the town. The method is set out in full on the how CIT testing works page.
What Counts as a Usable Detail
Not everything you have found will work. These are the kinds that tend to.
- A first name from a message, a call log or a contact, where your partner has no innocent reason to react to that name. If it is also the name of their sister, their manager or a close friend, it cannot be used.
- A venue: a hotel, bar or restaurant from a receipt or statement, provided it is not somewhere they go in the ordinary course of things.
- A town or area from a location history or a ticket, somewhere with no ordinary connection to their work, family or routine.
- A date or day that would stand out only to someone who knew what happened on it. Dates are harder to build lists for and are used less often.
- An object or gift: something bought, received or left behind that you have found and not mentioned.
- A phrase or nickname seen in a message.
Each of these must pass the same three checks as in any CIT. An involved person would know it. An uninvolved person would not. And five believable alternatives can be written, so that someone with no knowledge could not guess which item is the real one.
What does not work
- Anything you have already said. If you have asked "who is Carla?", the name is now known to your partner because of you.
- Anything they know for everyday reasons. A colleague's name, a pub near their office, the town their parents live in.
- Suspicions without a specific. "They have been distant", "they guard their phone", "they come home late". These may be real observations, but none of them is a detail to recognise.
- Things that are probably widely known. If you have discussed it with mutual friends, assume it could have travelled.
The One Rule: Do Not Reveal What You Know
This is the hardest part, and the part that most often decides whether a test is possible.
When you find something, the natural reaction is to confront. It is completely understandable. It is also the action that destroys the test. The moment you say the name, show the receipt or ask about the town, your partner knows that detail, and from then on their recognising it tells nobody anything.
If you are considering a CIT and you have not yet raised what you found, hold it back. That includes:
- not asking leading questions that contain the detail, even casually
- not hinting ("I know more than you think" is fine; "I know about Knutsford" is not)
- not telling friends or family who might pass it on
- not leaving the evidence where it can be seen to have been found
If you have already confronted them about some things, tell us exactly what was said. Often there are other details that were not mentioned and can still be used.
What the Results Would and Would Not Mean
It is worth thinking this through before the test, not after.
If a detail is recognised
It means your partner's brain responded to that item as significant when it did not respond that way to the alternatives. It indicates that the name, place or thing is familiar and meaningful to them. It does not, by itself, tell you what the connection is. A recognised name is a person they know of. A recognised venue is somewhere that matters to them. What you conclude from that depends on what they have previously told you. If they have said they have never heard the name and never been to the place, recognition of both contradicts their account.
If a detail is not distinguished
It means there was no sign of recognition on that item, in a recording that passed its quality check. It is consistent with your partner not knowing the detail. It is not proof of anything wider. They may have no connection to that name because you were mistaken about what the message meant, and it remains possible for someone to be involved with a person or place that was not on your list.
If a block is unusable
It means the recording could not support a conclusion, usually because of movement, poor contact or a missing response to the target. It says nothing either way.
Several details together
The strength of a CIT grows with the number of independent details. One recognised item could be coincidence or an unlucky choice of word. Two or three recognised items, each from a separate list, form a pattern that is much harder to explain innocently. Equally, two or three flat responses on well-chosen details are more reassuring than one.
We report what the recording shows for each detail. We do not report a verdict on your relationship, and we do not tell you what to do next.
Your Partner Has to Agree
There is no version of this test that can be done without them knowing.
The person tested must consent in writing on the day, after the examiner has explained the procedure to them directly. They can decline, and they can stop partway through. We will not proceed if it appears that someone has been pressured into the room.
How you raise it is your decision, but honesty about the format helps. You can truthfully say that they will not be asked any accusing questions, that they will watch words on a screen and press a key, that it takes around an hour, and that it measures whether particular things are familiar to them. You should not tell them which things.
Some people ask whether a refusal means something. We would not read anything into it. People decline tests for many reasons, including distrust of the method, pride, or simply not wanting their relationship examined by a stranger.
When the accused partner asks for the test
The CIT is also used the other way round. A partner who has been accused and has nothing to hide can ask to be tested on details the other person holds. The suspicious partner supplies the details to us privately. If those details mean nothing to the tested partner, the recording should show flat responses. For some couples this is a more constructive route, because the test is something the accused person chooses instead of something done to them.
If You Have No Details
This is the position many people are in. Here is what is and is not possible.
Without a withheld detail there is no probe, and the standard CIT cannot be built. Asking your partner to take one anyway would produce a result that means nothing.
There is a second form of the method, the searching CIT, in which the list contains candidate answers and the analysis looks for one that stands out. In a relationship case that might be a list of names of people in your partner's circle, or a list of places. It is a recognised method: the Japanese police use searching tests in field work. But you should understand its limits before considering it:
- It can only find an answer that is on the list. If the true answer is not among the candidates, nothing will stand out.
- Names and places from someone's own life are all familiar to them, which makes any one of them harder to separate from the rest.
- It needs more repetitions and more than one block before a pattern can be reported, and inconclusive outcomes are common.
- A result of "nothing stood out" tells you only that no item on those lists stood out. It does not clear anybody.
For many people with no details, a test is not the right step. A direct conversation, time, or the help of a relationship counsellor may do more. We would sooner say that than take a booking for a test that cannot answer your question.
How the Alternatives Are Chosen
In a relationship case the false items need as much care as the true one.
Take the example of a first name. If the name you found is Carla, the other five names on the list have to be ones that mean nothing in particular to your partner. That is where your knowledge of their life becomes essential. We will suggest names of similar length, familiarity and style, and you strike out any that belong to a relative, a former partner, a close friend, a colleague they talk about, or anyone else who matters to them. A name that already carries weight would draw a response for its own reasons and muddy the comparison.
The same applies to places. If the detail is a town, the alternatives should be towns of a similar size and distance, none of which is where they grew up, where they work, where their family live or where you went on holiday together. For a venue, the alternatives should be real or realistic venues of the same type that they have no history with.
The target item is chosen the same way: an ordinary name or place with no special meaning, which your partner will be asked to press a different key for.
This is why we build the lists with you over a call or by message before the appointment, and why we ask a lot of questions about what might be significant to your partner. You know things about their life that we cannot.
Mistakes that weaken a relationship test
- Using a detail you are not sure of. If you only think the name might be Carla, and it is wrong, a flat result tells you nothing. Use details you are confident of.
- Testing too many things. Two or three strong details are better than six weak ones. Tiredness degrades the later blocks.
- Sitting in on the test. Your reactions could signal which word matters. You will be asked to wait elsewhere during the recording.
- Raising the details the night before. An argument on the eve of the test, in which the name comes out, undoes the preparation.
- Expecting the test to settle everything. It answers a narrow question about specific details. The wider question of what you both do next is still yours.
Before You Book
A few things worth weighing first.
Think about what you will do with each outcome. If a detail is recognised, what then? If it is not, will that settle your mind, or will the doubt move somewhere else? A test gives information. It does not repair trust, and it is not a substitute for the conversation that follows.
Consider the effect of asking. Requesting a test tells your partner that you do not believe them. In some relationships that is already in the open. In others it is a step that cannot be taken back.
Understand the evidence. Laboratory studies of the P300 CIT commonly report detection of 80 to 95 per cent of people who hold the tested information. Those are laboratory figures, mostly from students tested on rehearsed details, and they are not results from our own testing. Field validation is limited. People can also be taught techniques that weaken the test; research in 2004 showed this for the protocol we use. Treat a result as one piece of information among others.
Look after yourself. Suspecting a partner is exhausting. If it is affecting your sleep, work or health, speak to someone you trust or to your GP, whatever you decide about testing. And if you are ever afraid of your partner's reaction, your safety comes first; a test is not appropriate in that situation.
Arranging a Test
What happens after you get in touch.
- You tell us, privately, what you have found and what your partner has and has not been told.
- We tell you whether a test can be built. If it cannot, we say so and no appointment is made.
- We draft the lists with you. You check that none of the alternatives has a hidden meaning for your partner.
- Your partner agrees to take part and an appointment is set, at home or at a private venue near you, anywhere in the UK.
- The examiner runs the test, which usually takes 60 to 90 minutes including set-up.
- The result for each detail is reported in plain wording, with the figures behind it.
You can check your situation against the full requirements on the who qualifies page, or read the CIT testing overview first.