The Uncanny Valley

I’m sure it isn’t just me. The cluttered, clanky movement of a prosthetic hand, the quite unfamiliar feelings directed towards the use of CGI in animating humans, or the humanesque yet gruesome faces of horror film antagonists—this is what we call, ‘The Uncanny Valley’.

The Uncanny Valley is a term that originated from Japan, first discovered and published by Dr. Masahiro Mori in the year 1978. It is a psychological phenomenon wherein as something starts to resemble a human, it starts to become more and more likeable, but only to a certain extent. As it approaches a state where it is rather human-like, but not quite authentic, our familiarity towards it steeply decreases. This is why it’s called a valley.

We can observe this phenomenon in many things, such as dolls. Dolls that are rather cartoon-ish give us a sense of comfort, wherein we consider it ‘cute’. But as it starts to closely resemble a human, we find it ‘creepy’, for example, wax figures. Another example would be horror movies. Imagine seeing a horror movie with, let’s say, Donald Duck as the antagonist. I doubt it’d be as scary as it would be humorous. But then, say, if we were to replace it with Annabelle, I doubt you’d be smiling anymore.

But wait… Why exactly does this mechanism exist? Is it important? Does it perhaps contribute any value towards our survival instincts? Well, there hasn’t been a definite answer thus far. But let’s first discuss how this phenomenon is triggered.

National institute of mental health (n.d.) Prefrontal cortex (diagram) 2017, https://www.psypost.org/depressed-people-medial-prefrontal-cortex-exerts-control-parts-brain/

The medial prefrontal cortex (diagram above), a wall of neural tissue between the right and left side of the brain, determines the value we put on different stimuli (Grabenhorst, 2019). For example, it controls the rewards system when we eat sugary foods, or foods we find pleasurable. This medial prefrontal cortex can be then divided into two parts. One part categorises the objects we see into ‘human-like’ and ‘unhuman-like’. The second part, the ventromedial prefrontal cortex (vmPFC), determines our likeability towards it.

In a study by Grabenhorst (2019) where the vmPFC was monitored by using an fMRI with specific conditions correlated to human likeness, with activity in this area of the brain increasing as human-likeness does, and dipping suddenly as it reaches near-perfect rendition of humans. Not only do these results follow the trend described by Masahiro Mori (1978), it also explains why we feel uneasy when watching horror movies, or why wax figures are rather creepy.

Back to the usage of this mechanism. This phenomenon is likely a defence mechanism from the days of our ancestors, when they had to hunt on their own and live in the wilderness. Since the medial prefrontal cortex controls the reward and punishment system (Grabenhorst, 2019), it’s likely that this system was used to differentiate between dangerous and rewarding situations. For example, both bears and deers are furry animals, but this area of the brain would help us determine which is safe and rewarding (deer) or dangerous and punishing (bear). If the line crosses somewhere in between, it will be hard to tell, and thus gives you that sense of uneasiness, not knowing whether it’s dangerous or safe.

Another usage of this mechanism is in avoidance of contagious diseases. Corpses, especially those caused by contaminants are often slightly deformed, with pale faces, rotting wounds or visible marks. Our medial prefrontal cortex will react, recognizing these as ‘humans’ but at the same time it isn’t able to confidently affirm whether they really are ‘humans’, due to the anomalies. This creates this sense of uneasiness, urging us to stay away from the corpse, thus preventing the spread of the contaminant.

References:

Caballar, R. D. (2024, May 24). What is the Uncanny Valley? IEEE Spectrum. https://spectrum.ieee.org/what-is-the-uncanny-valley

MSEd, K. C. (2024, July 8). What to know about the Uncanny Valley. Verywell Mind. https://www.verywellmind.com/what-is-the-uncanny-valley-4846247

Scientists identify possible source of the ‘Uncanny Valley’ in the. (2019, July 1). University of Cambridge. https://www.cam.ac.uk/research/news/scientists-identify-possible-source-of-the-uncanny-valley-in-the-brain

Wikipedia contributors. (2024, September 22). Uncanny valley. Wikipedia. https://en.wikipedia.org/wiki/Uncanny_valley