The Tactile Interface of Driving a Car

Tactile interface is not something new. We have instinctively built tools on that premise for thousands of years: tools made to fit and attract the human hand that can, and should, be operated without looking. We have traditionally produced tactile interface through mechanical means such as knobs, handles and shiny physical buttons. I like to think about that when trying to create tactile interface.

The tactile interface of a car.

For example, I drive my car without looking at the controls. That is because it is focused on tactile interface. Cars are built with buttons to push, pedals to depress, levers to flip, and a wheel to turn. The steering wheel not only has indications of how it should be operated and where my hands should go, but through it, I can also feel the road surface. Secondary, but important, and frequently needed controls, like turn signals and wiper blades, are given significant tactile presence. These are usually levers that I can easily locate without ever taking my eyes off the road. In these instances, their feedback is also tactile: Up (with a click) is always right, down (with a click) is always left. I know by the clicking that I’ve twisted the knob once for slow  wipers and three times for fast.

Even our brakes are designed for tactile interface. The brake pedal is on the left and is wide and short versus the gas pedal on the right that is skinny and tall. If I take my feet off the pedals, I can quickly, without looking, tell the difference between them because of their placement and how they feel under my feet. A driver knows when a car’s anti-lock brakes are engaged because the pedal does a little pump action that the driver can feel in his foot. This is because traditional brakes required the driver to pump the brake with his foot. This action prevented the brake from locking up and causing the car to skid. Automatic anti-lock brakes, introduced in the 1980s, do this action automatically for the driver. However, if the driver pumps an anti-lock brake system as he used to with traditional brakes, it would cause the brakes to fail and lock up. So, when cars started to include automatic anti-lock brakes, the manufacturers made it so that the brake pedal physically communicated to the driver that the anti-lock brakes were doing their job and pumping already. Now, when the brakes are engaged, the brake pedal does a slight stutter, telegraphing up the driver’s leg that the brakes are working.

The early car stereos are also great examples of a tactile interface. For the most part, they were designed to be operated eyes-free. One could clearly feel the buttons and there weren’t too many of them. If the driver turned a simple dial, it would scroll through his options giving an audio snippet of what is next on the radio stations. Most cars made today have moved the most essential stereo operations onto the steering wheel in mechanical buttons to facilitate simpler, more natural tactile interactions. Drivers don’t even have to move their hands from the wheel–song selection and volume adjustment are just a thumb press away.

The tactile interface of a car has always allowed us to operate it in an easy and intuitive way which allows us to focus our eyes on the road while driving. How can we take these lessons and incorporate them into digital devices to make it easier, and more natural, to interact with technology?

Learnings from the Tactile Interface of Driving a Car

  1. In heads-up operation, make sure to consistently place and group objects so that the user can instinctively reach to that area to do task x.
  2. Provide a tactile hierarchy. For example: the hazard lights are bigger than the radio buttons, which is smaller than the turn signals, which are all smaller than the steering wheel.
  3. Provide tactile affordances. The shape and size of the tactile element should indicate to the user what to do to activate that element.
  4. The feedback on that element must also be tactile, even if it is accompanied by voice or action.

Next time you are in a car, notice how much you can do without looking. What else do you operate solely through touch?