July 25, 2021

I, Science

The science magazine of Imperial College

Yu Hang Hui. runner up from the I, Write Competition, explores how language and culture can influence our perception of what we see and hear.

Red, orange, yellow, green, blue, indigo, and violet: t he colours of t he rainbow!

Yet our eyes deceive us, because physics clearly demonstrates that the colour spectrum is a continuum of colours rather than distinct groups of colours. So why do we see 7 distinct colours?

Categorical perception is a phenomenon in which t he way our brains categorise objects influences how we perceive our surroundings. The perceived differences between items from different categories are accentuated, while the unique aspects of items in the same
category are harder to distinguish.

In t his instance, the colour terms we acquire as children affect our worldview. For example, as we l earn t o distinguish when something is ‘red’ and when it is ‘orange’, we become accustomed to these language terms, and we begin to exaggerate the characteristics of ‘red’ and ‘orange’ to better place colours into categories. The result is that we perceive a clear
boundary between ‘red’ and ‘ orange’, when in fact, it is blurred.

But what if I were to say you do not necessarily have to see 7 colours in a rainbow? And what if I told you that where you identify the red-orange boundary may be different from where others place the boundary?

The categories we acquire are not the same for you and me. After all, language is nothing more than meaning attached to a string of otherwise arbitrary sounds, so the categories which stem from language must also be random to a certain extent. Differences in our language and culture result in us becoming accustomed to different categories, directly impacting the way we perceive the world.

Blue and blue are not the same!

Голубой (goluboy) and синий (siniy) are the Russian words for light blue and dark blue, respectively. There is no single Russian word that describes what English speakers label ‘blue’. To Russians, “голубой” and “синий” are 2 distinct colours, similar to how English
speakers see red and orange as 2 different colours.

One 2007 study investigated how variations in the way language is used to describe colours affect how colours are perceived. Native Russian and English speakers were presented with three ‘blue’ coloured squares arranged in a triangle and asked them to pick out the square on the bottom which matched the one at the top.

An example of the squares shown to the Russian and English Subjects

The Russian speakers selected the correct square much faster than the English speakers when one square was “голубой” and the other was “синий”. In other words, categorical perception gave the Russian speakers a slight advantage in the task because they were accustomed to distinguishing the difference between ‘blue’ hues.

The biological misconception

The most common perception about categorical perception is that the differences in observations owe to inherent biological differences of different groups of people. This is simply not true.

Let us consider the famous Himba colour experiment conducted by researchers Goldstein, Davidoff, and Robertson in 2008. As opposed to the 11 colour terms in many modern languages, the Himba people residing in Namibia, Africa only use 5 colour terms. For example, ‘zoozu’ describes dark colours such as black, dark red, dark blue and dark purple, while ‘burou’ describes greens and blues. Due to categorical perception, the Himba people find it more difficult to discern ‘green’ and ‘blue’ hues.

In the experiment, toddlers from the United Kingdom and the Himba tribe were shown a particular-coloured object for 5 seconds, then asked to select the same colour frrom 2 objects. The toddlers have not learnt colour terms. If the argument for inherent differences in vision is valid, Himba toddlers should be less able to distinguish colours and therefore perform worse than English toddlers.

Not surprisingly, the Himba children did just as well as the English children, demonstrating that understanding colour terms is required for categorical perception of colour. Without categories, there is no categorical perception. When categories have not yet been aquired, nothing differentiates different groups of people in their observations of their surroundings.

Another study discovered that Japanese speakers who are experienced at speaking English are much more capable of distinguishing ‘r’ and ‘l’ sounds than their monolingual counterparts. This reflects the experience of anyone who has ever learnt a foreign language. While it is initially challenging to hear the distinctions between unfamiliar sounds, we gain an understanding of different phonemes after exposure. This conclusively demonstrates that categorical perception can change over time.

Therefore, we can understand that differences in perception only manifest due to nuances in language and culture, and that categorical perception can be gained and adapted through new experiences.

To summarise, categorical perception is a fascinating phenomenon in which the categories we are accustomed to influence how we perceive our surroundings in daily life, including what we see and hear. Despite these differences, we essentially possess the same abilities to live our life and adapt to our experiences.

Categorical perception is advantageous in allowing is to easily process and standardize the information we receive, but these categories also temporarily inhibit our ability to adapt when immersed in a different environment than the one we are accustomed to. In other words, the categories we acquire are tools that optimize daily communication with other people, but the same toolset is not suitable for all scenarios in such a diverse world.

More generally, we must be respectful and patient with others who momentarily interact with information differently. If anything, categorical perception demonstrates there are no inherent differences between different groups of people, except the ones we learn. We are all intrinsically equal.


Yu Hang Hui is from Island School in Hong Kong.