Subliminal Stimuli and its Neurological Affects

Subliminal messages have been used since time immemorial, but researchers are yet to give a very concise explanation of, both, whether it works and if it does, how?

By Neha Menon

Published 6:12 PM EST, Fri April 16, 2021


Subliminal messages have been used since time immemorial, but researchers are yet to give a very concise explanation of, both, whether it works and if it does, how? In simple words, “any sensory stimuli below an individual’s threshold for conscious perception is called a subliminal message.” (Wikipedia)

Consciousness, put very plainly, is the state of being aware – aware of one’s surroundings, thoughts, emotions and the external & internal environment. On the contrary, the unconscious state of mind is one wherein there lies “a reservoir of feelings, thoughts, urges, and memories that are outside of one’s conscious awareness.”[1] This consciousness is enabled by the part of our brain called the cerebrum, whereas the unconscious actions are performed by the basal ganglia and cerebellum. This concept may be  attributed to Sigmund Freud – Austrian neurologist and the founder of psychoanalysis. The discussion of the conscious and unconscious state of our mind highlights the core topic of this article: subliminal primings or subliminal messages, which were brought to the mainstream media as early as 1957.[2]   However, extensive research and scientific opinions on this subject have only emerged in the recent years. This is discussed in further topics.

Primarily, subliminal messages work by nudging your unconscious. This would imply that by listening or looking at a subliminal message, we are gathering information or getting affected unconsciously. This is why, before we look at the ‘what, why and how’ of subliminal priming, we must understand the theories of the unconscious state of mind, which will give a great deal of insight regarding the direct workings of a subliminal message on the brain.

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“The mind is like an iceberg, it floats with one-seventh of its bulk above water.” — Sigmund Freud.

The Unconscious State of Mind

It would be beneficial to understand first that the conscious state of mind is finite. If we were to notice and process (consciously) everything that we see, hear or feel in a day, our brain would be far too overwhelmed and the retention of this information may be compromised. The unconscious, on the other hand, is vast – limitless – to say the least. Everything we see, hear or feel goes into our unconscious but doesn’t necessarily get processed. This means that the way we perceive something may not be the actual reality of it.

Secondly, it is important to note that the brain can only perceive something in the way and form that it first enters our mind. Meaning, imagine a picture, for instance, that could be perceived in two different ways based on how you look at it. Perhaps (as shown in the image below) : an old woman who, if and when the perspective is changed – looks like a young girl. Your brain may be able to identify these two ‘forms’ of the same picture but it will not be able to see both forms at the same time.

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Image credits: public domain

The “How” Of Subliminal Messages

Once we know how the unconscious mind works, we can move on to explore why and how subliminal messages affect our brain neurologically.

In subliminal messages, there are multiple items (audio/video/picture) that require relational processing. This may  be compared to the picture discussed above, which can be seen as two separate images. Relational binding hence calls upon the hippocampus – a complex brain structure embedded deep into the temporal lobe. It has a major role in learning and memory. Hence in this case, it can rapidly store novel relations for a longer term. Usually, it is known that the hippocampus is involved in the encoding and retrieval of consciously perceived information.

“However, growing evidence suggests that hippocampus operates independently of consciousness and that nonconscious relational learning is humanly feasible”[6]

While talking about the direct effects of subliminal stimuli on the brain, they robustly activate certain parts:

Amygdala – It is recognised for its role to process emotions. It is the part of the human brain best known for its ability to drive the ‘fight-or-flight’ response and also plays a vital role in memory. 

Insula – The insular cortex links sensory experience and emotional stimuli. It is also linked with conscious emotional feelings

Hippocampus – It plays a part in memory consolidation: the process of transferring new learning into long-term memory

Anterior cingulate – has been implicated in several complex cognitive functions, such as empathy, impulse control, emotion, and decision-making.

We see that most of the affected parts have a role to play in emotional valence or memory. It is these parts that are activated when your brain is exposed to subliminal messages.

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Subliminal Messages In The 1900’s

When the history of subliminal messages is regarded, we see that most of them were used in marketing, or advertisements. The following timeline shows some of the important milestones in the history of use and discovery of subliminal messages:

1943 – Subliminal messages were occasionally used on the radio and television programs. [3]   

1990 – Many researches showed little or no link in the subliminal messages and the psychology of the brain, while others started uncovering subtle effects. [3]   

2006 – Studies showed and proved that subliminal messages did work in several advertising scenarios.  [3]   

2007 – Subliminal messages for academic performance were uncovered and studied. [3]  

2010-2015 – Imaging proved that subliminal messages did affect several parts of our brain, including but not limited to the visual cortex and hippocampus[3].   

Other common forms of subliminal messages in recent years are:

  • Images being inserted into the frames of movies, trailers, commercials etc., for an extremely short amount of time in such a way that the brain cannot consciously comprehend it.
  • Audio messages inserted under louder audio messages in order to mask it.

The “Why” Of Subliminal Messages

Subliminal messages and stimuli have been used in several places for several different reasons. 

  • The most common of all, is advertising and marketing. Companies like Coca-Cola show a good example of subliminal messaging for marketing in the late 1900s. Here the words “Buy Coca-Cola” and/or “Buy Popcorn” were flashed into movie reels.
  • For political agendas, like the one in the George Bush campaign in 2000. The opponent, Al Gore, accused Republican campaign managers of including a subliminal message in an attack ad focusing on Gore’s proposed healthcare policies. The word ‘RATS’ was flashed quickly right before the presentation of the word ‘bureaucrats’. 
  • In Disney movies like Aladdin, The Little Mermaid and The Lion King. It is unclear what the agenda for these were, and whether they were intentional at all.
  • In more recent times, subliminal messages have been famously used as auditory sources – melodic rhythms in particular. These claim to be able to change several things in your physical and mental realms; from removing mental head-block to changing eye color or weight. It’s efficiency or lack thereof, is not proved yet.


Exposure to subliminal stimuli have been proved to have certain effects on the human brain through research and experimentation. The efficiency, however, is not ensured. According to a UCL research, subliminal messaging is most effective when the message conveyed is negative in comparison to when it is positive. [7] Certain subliminal stimuli (especially now that the concept has taken pace) may have harmful impacts on the brain. They cannot damage the brain per-se, but can have negative impacts on your subconscious mind.

Neha Menon, Youth Medical Journal 2021


Cherry, K. (2020, December 09). The Structure and Levels of the Mind According to Freud. Retrieved from[1]

6 Examples of Subliminal Advertising, from Spooky to NSFW. (n.d.). Retrieved from [2]

Stern, V. (2015, September 01). A Short History of the Rise, Fall and Rise of Subliminal Messaging. Retrieved from [3]    

Sigmund Freud. (n.d.). Retrieved from [4]  

Subliminal stimuli. (2021, February 16). Retrieved from [5]

Ruch, S., Züst, M. A., & Henke, K. (2016, August 20). Subliminal messages exert long-term effects on decision-making. Retrieved from[6]Ucl. (2018, November 15). UCL study: Subliminal messaging ‘more effective when negative’. Retrieved from [7]


By Neha Menon

Neha is a student from India who is passionate about psychology and neuroscience and loves researching on these topics. She hopes to build a career around clinical psychology.

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