The upcoming pseudoscience of lie detecting

Written on 08 Mar 2025

Just a little disclaimer, this is completely 100% an opinion. Take everything I say here with a grain of salt and if you are a student please don’t cite me as a source. With that’s being said, let’s get on with the post.

In the last 200 years, we have seen an explosion in the area of science, but with that we have seen entire fields of science come and go. Over 100 years ago, fields such as Phrenology and Eugenics were still seen a legitimate fields of scientific study, and now they largely aren’t. Sometimes I wonder what fields of study we consider legitimate today in 2025 that will be seen as complete pseudoscience in 2125.

Psychology is home to it’s own subfields, and in that we find the still popular notion that it is possible to accurately detect a lie without having hard evidence. I think that in the next 100 years, we will see the scientific credibility of this idea crumble into oblivion.

We are already starting to see the cracks in this idea form. Polygraph machines (also known as lie detecting machines) have been found to be quite inaccurate at detecting lies to the point where in many countries they are no longer permissible as evidence to a crime. Still, popular media still for some reason gives them much more credibility than they actually deserve.

If you take a look at the rest of the methods used to detect lies in the absence of hard evidence, they have at best a moderate correlation with someone lying and at worse point to something else entirely. One of the better methods is seeing if someone tells two different stories at two different times, but even that is shaky as anxiety or general forgetfulness while being put on the spot can lead to people prioritising different details leading to a somewhat different story if you ask them again, even if they are being truthful.

The worst methods involve the use of body language, the specific way they answer a question, or the tone of their voice to indicate if someone is lying. This doesn’t measure lying, it measures anxiety. While it is true that people who are lying are typically more anxious, being put on the spot especially if being accused of something will also cause anxiety that will manifest in a similar way whether someone is telling the truth or not.

Most lie detecting methods are already sketchy enough when used against neurotypical people, but against neurodivergent people they are even less accurate. People with conditions such as ADHD, Autism, some personality disorders (such as Antisocial personality disorder) and more will often respond in a much different way both verbally and non-verbally to lie detecting methods than a neurotypical person does which will result in false positives and false negatives more often than when the same methods are used against a neurotypical person. Effectively, many lie detecting methods shaky enough as they are become absolutely useless at telling if someone is lying if used with a neurodivergent person.

We’ve even found out that your own family who have known you for your entire life can’t accurately tell if you are lying or not without concrete evidence against your claim, and that your own family is hardly better than a stranger at detecting a lie without proper evidence.

The only way to be able to know with reasonable accuracy if someone is lying or not is to have hard evidence against their claim. If little Robert stole a cookie from the cookie jar and you don’t have a camera pointed at the cookie jar or you did not witness it yourself, you have no reasonable way of knowing if he lied about stealing a cookie. There are other explanations that are just as valid as “he lied” such as you misremembering the amount of cookies in the jar.