Frequency illusion Explained

Frequency illusion Explained

Imagine, for a minute, that you have just learned Tehran is the capital city of Iran. Prior to this, you knew absolutely nothing about Iran, its culture or its history. Now, virtually everyone you meet just so happens to be from Tehran. A strange phenomenon, to be sure.

It all has to do with the memory and it is called the frequency illusion. Do not be surprised if you have experienced something similar, as the frequency illusion affects everyone at some point. Most of us won’t even think twice about it, much as déjà vu is a curiosity that is quickly forgotten also. Assistant Professor Carly Leonard of the University of Colorado Denver’s Psychology department sums up the Frequency Illusion as being something that occurs because things that have recently been considered important to you are processed with more attention by the brain and thus become more consciously perceived.

Another example would be that you have recently bought a flat cap and because of this, flat caps have become more noticeable. Frequency illusion is a perfectly natural occurrence, although it may come as a surprise when it is first experienced. The brain has acquired some new information and is naturally reinforcing it.

Why does it happen? The brain is exposed to a great deal over the course of one day and cannot absorb every detail. The brain must thus decide which information to process and which to discard. In this way, the brain ignores information which does not immediately seem important. When you learn something new, and this is especially true if you learn something interesting, the brain realises this and acts accordingly.

The interesting new information will in all probability be preserved for a considerable period of time, perhaps forever, and naturally it will remain at the front and centre of the brain’s attention for a while. The illusion goes by multiple names. The frequency illusion is the most common as those who have it notice specific things frequently.

It is also known as the recency illusion on account of noticing something that you have recently learned about. Less commonly, it is known as the Baader-Meinhof phenomenon, due to one its most noticeable cases in which a man wrote a letter to a newspaper mentioning that he had heard the name Baader-Meinhof Group (a West German militant group) from one source and then coincidentally came across the name again via a different source. This prompted a flurry of similar letters to the newspaper from people who claimed they had had the same experience, thereby giving rise to the colloquial name ‘Baader-Meinhof phenomenon’.

The illusion is also known by the name ‘selective attention bias’. The term “frequency illusion” was coined in 2006 by Stanford University professor Arnold Zwicky in a scientific paper he called Why Are We So Illuded? He defined the illusion as first noticing and then believing something happens regularly. He described the illusion as consisting of two separate parts. First, there is selective attention bias, which means we notice things that are of particular interest to us while disregarding everything else.

The second component is confirmation bias, in which we seek out evidence that supports our belief or way of thinking despite the strong presence of evidence to the contrary. Whilst the illusion is mostly harmless, it can cause the symptoms of schizophrenia to worsen and can also have legal implications in terms of the reliability of eyewitness accounts in court as personal recollections can be influenced and manipulated by the phenomenon. More seriously, a detective searching for the culprit of a crime can become fixated on one particular suspect via this illusion and potentially allow the real guilty party to slip through their fingers.

Alternatively, a doctor, having made a certain diagnosis, could become fixated on it and diagnose people with it even though they are afflicted with other unrelated conditions. A June 2019 article in Academic Radiology told the story of a medical student, who having successfully diagnosed bovine aortic arch in one patient, went on to correctly see it a further three times in 24 hours.

The article was at pains to point out the illusion’s efficiency as a learning tool. For most people however, their experiences of frequency illusion will not result in outcomes as drastic as these. Mostly it is regarded simply as an interesting phenomenon.

It does shine a particularly interesting light on attentional processing; that is, it demonstrates that any given moment, a lot of sensory input is being disregarded by our brains whilst a smaller amount is focused on almost exclusively. The frequency illusion is frequently used as a marketing tool. If you have ever seen a particular advert over and over again, does your mind eventually start to convince you that the item being advertised actually seems desirable and worth purchasing? If so, that is the frequency illusion in action. The illusion becomes less effective if the potential buyer takes time to research the product and reach their own conclusion.

Common ways of triggering the illusion in the minds of customers include distinctive headlines and striking images. Videos are also a useful tool in this regard, as is constant repetition, particularly placing the same message on various social media platforms. In conclusion, the frequency illusion is when something you have recently learned begins to appear over and over again in your personal life, or at least it would appear to.

In reality, it is the product of your frequency bias going into overdrive. Whilst in the wrong context it can be a serious annoyance and even a danger, by and large it is simply a curious phenomenon that stirs up interest more than anything else. Can you think of any times in the recent past where you have experienced the frequency illusion for yourself? It happens more often than you might think.


This article is for educational and informational purposes only and must not be used or taken as a substitute in any form for any medical advice, medication you are currently taking or any alternative treatments without the prior advice, guidance and consent from your medical doctor. Please speak with your doctor first before making any changes to your diet or medicine as a result of reading any information laid out on this website or in this or any other articles.

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