You CANNOT drive on Chinese soil

Sorry, you cannot drive in China

I was working on getting my US driver’s license changed to a Shanghai one. I’ve heard terrible stories that all said getting a driver’s license here is largely an ordeal. You have to take a driving class and bribe your teacher even if you already pay all the fees, and stuff like that. In the US (for example, in Texas), you pay 20USD and take a test, and that’s about it.

Life is much easier if you already have a license from another country,  which might save you loads of troubles. Basically you get your license translated into Chinese by a certified agent (50rmb), then go to the police department that is in charge of processing driver’s license applications, pay all the required fees (photo taking 60RMB and health check 40RMB, health check for a driver’s license? anyways), take a written test (I did not get to this far), and then you are done.

For my case on last Wednesday, everything went quite smoothly as planned, at least for the earlier part. But…., after the health check found me "color blind", I was out. Yes, out! for my life time to be a driver in my own country. Well, I was not surprised that I have color deficiency. Specifically, I have subtle trouble in distinguishing red-green mixtures in some conditions. I will come back to the pop science of color vision below. I knew this since I was a child. In fact, it’s an inherited deficiency, from my mom who is color blind as well.

However, I was upset (still unsurprisingly) by the fact that one cannot drive just because that he/she is color blind. The society provides no room to accommodate you. Well, in this country, this reality is not a big deal and it is just the way of life. For example, you can be deprived of education opportunity if you have a hepatitis (it happened to a graduate applicant to our institute last year) or a heart condition (it happened to my cousin more than twenty years ago even after he passed the entrance exam, twice). You have a problem? You eat it. Sorry, no social help for you. The mindset goes like "you are the problem for the society and you should feel ashamed", and never like "the society should do better to help you to develop"

Human vision of color

So, what is color blindness? Can you tell the number buried in the following color diagram? If not, you are perhaps color blind. I can tell there is a 2 (red color) to the left, but cannot tell the number to the right.


Color blindness is a strong and disproportional term, which is often
misleading. Most color-blind people like me only have a certain degree of
deficiency in color perception, not a complete loss. It’s not true that we can only see black and white. That’s totally not cool! You can only find one such case in 10 million people, meaning that there are perhaps two people in Shanghai who can only see black and white.

The science behind color vision is technically called "trichromacy", which is a complex mechanism that human eyes use to percept color. In short, retina contains four types of cells — rod cells and three types of cone cells. Each type of cone cells has a light absorption spectrum that spans a certain wavelength different from the other types. The combination of three spectra from the three types of cones spans the entire visible light spectrum such that human can distinguish color based on the wavelength sensitivity of cone cells and color intensity received. The plot below shows absorption spectra of human cone cells (for details, see this wikipedia entry). Letters ‘S’, ‘M’ and ‘L’ indicate short, medium and long wavelength, respectively. The black curve is the spectrum of rod cells which can assist in color perception at a low light condition. The closeness between the M (green-sensitive) curve and the L (red-sensitive) curve explains why most color-deficient patients are green-red deficient because the distance between these two curves can be obscured by relatively minor disruptions.


The majority of people with color deficiency are born to it, indicating it is mainly a genetic disorder. Color blindness is also sexually disproportional. Among Asian population, near 5% of all males are color blind, compared to only 0.4% of all females (so, my mom is very special with regard to this fact). The explanation has to resort to recessive gene inheritance in X chromosome. I am not going to get into the details of this. Go studying some basic high school genetics if you are interested. Or, go to to check it out.

OK. So, can you drive if you are color blind?

A more relevant question is "Can color-blind people drive?" The short answer: yes. In fact, most countries issue driver’s license to people regardless of their color perception. There are a few countries that still decline driving rights to color-deficient people, like Singapore (a collective society, no wonder).

The major concern for color deficiency is the ability of accurately recognizing traffic lights. Again, as I mentioned above, the majority of color-deficient people
have little problem in telling the differences of plain colors, which
is actually the case for traffic lights. Also, traffic lights almost always go in fixed orders with red on top, yellow in the middle and green at the bottom, or red to the right, yellow in the middle and green to the left.  This actually eliminates drivers’ the reliance on color. Traffic lights can be distinguished by its intensity as well. Finally, it can be also a design issue. In places in Canada, traffic lights not only show green, yellow and red, but are also in different shapes, which help people with color deficiency to properly recognize signals.

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