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Universal Design

Which side do you drive your interface on?

The other day I think I came across something that further opened up my thought process as a designer.


Creating an interface for a healthcare application aimed at easing the workflow for a CT Scan for a radiologist and/or technician.


The use-case was such that the user needed to select the type of patient — adult or child, in case that information was not already available. The user can then select a body part of the selected adult and/or child that has to be scanned.


The resultant interface looked something like this.

The child on the left and the adult on the right.


Testing this with the user I got to know something. Something that seemed benign at first but was infinitely profound once I got into the black hole of my habit of recursively asking myself — Why?

The A/B

The user happened to have used a similar control to select the patient body part and the interface they used can be simplified as:

Adult on the left and child on the right

They said that this was ‘better’. It was my job to make sense of it and decipher why the hell! For me, the top option was an obvious choice. The rationale was simple — a child on the left followed by an adult illustration to its right. It maintained chronology, enter the screen from the left, small to big, and exit the screen from the right; so I thought. But then,

Light Bulb moment

Walking back home from work, while waiting for the crossing signal to go green, I noticed this.

If you ignore the ‘Abolish Capitalism’ sticker (which you shouldn’t), you can see this sign. The sign depicts the mother on the left and the child on the right. And this sign was everywhere. Now I cannot stop noticing this sign. Pedestrian zones, School zones, playing zones, etc. This made me wonder if the prevalence of this sign has led people to be comfortable with the adult being on the left. That’s why the Adult-Child CT scan interface might be home for them. But then, why is it so alien to me? It took me more than just holding down shift and left arrow to move the Adult illustration to the left — it physically felt super weird.

Just then I noticed another sign. Near a school. Possibility of kids running on to the street. And here the child was on the left. It was swapped! This sign implied that the child is running towards the street on oncoming traffic and that sign was surely unnerving. And that’s when it hit me. Back in India if you wanna run on to the street you run in the right direction. Ah yes! The driving directions are swapped! Parents (the eternal selfless protectors) make their children walk from the inside and away from the traffic. This away from traffic is the other way round in countries with right hand driving. Back home in India, the parent would be on the right, the signage too! Though India’s signage game is not that strong, you can see this with England for example.

There are these things that one can only learn when one moves locations, situations, circumstances, demographics

There are these things that one can only learn when one moves locations, situations, circumstances, demographics etc. And for a designer, it sure is a great insight generator. This whole postulation might be wrong, and there could be more to it. If you do know of a better reason, or another theory perhaps, do enlighten us!

Unnecessary thought spiral, perhaps

The recursive questioning of ‘why’, wasn’t going to stop there though. Why do we drive on the side of the road where we do? It was again, as most things (such as today’s date and how you decide what is ‘western’ world and what is ‘eastern’); it had to do with the Englishmen!

Most of the world we see today was built by colonizers. The user persona was a white right handed man. Ergo, the sword wielding right hand. One would always be able to strike an oncoming knight if they were on the right of their horse. Furthermore this meant that the sword needed to be worn on the left leg making the left side heavier. Thus easier to jump the right leg over the horse while the left remains on the saddle stirrup.

After this, with the increased usage of horse carriage and wagons, things started changing with now the sword wielding right hand was replaced by horse-whip wielding right hand, making the driver sit on the left of the carriage, thereby forcing carriages from the opposite direction to pass over the left. From there, few too many feudal conflicts later, we have the world as we have it today.

Hush! Medieval horsemen to today’s CT scanning interface. Its been an interesting run!

If you liked reading this article, consider reading more on the Why’s of Design, or How’s of Architecture.

Keep observing the world. And, observe why you observe what you are observing. Ah! :)



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