The Design of Everyday Things

In his book, The Design of Everyday Things, Donald Norman provides the Mercedes Benz seat controls as "an excellent example of natural mapping." If you look closely at the picture on page 24, you will see that the headrest adjustment is placed behind the seatback adjustment. Logical given the real estate on the door panel- perhaps? Fast forward to 2002 and look at the following picture taken of a Mercedes Benz seat control.

The controls really mimic the shapes of the headrest, seat, and steering wheel. Push the headrest button up and the headrest moves up. Pulling the steering wheel button closer to the seat and it move closer to the driver; move it up and down and the steering wheel moves up and down. Excellent just got even better!





In the same car, the HVAC controls are less clear. The user can expect these controls will operate the air conditioning, heating, etc. (affordance). The buttons to produce warmer (red) and cooler (blue) air are clearly marked with the added bonus of temperature readings in the digital display (visibility).

If you inspect the air flow controls (Can you tell where they are?) There are arrows and icons that make little to no sense. If you want to engage the air conditioning, which button do you use? Can you tell what happens if you push the button on the left next to the digital display? The mapping of many of these controls is less clear. The owners manual dedicates 8 pages to the operation of the HVAC system. By the way, when you purchase a Mercedes Benz, there is an orientation (30 minutes) given on the car before you drive it off the lot. If you have questions, There is a 384 page manual provided. And if you don't want to carry it in your car, you can keep the quick reference manual (18 pages, spiral bound) with you instead.

So now fast forward to 2008 and look at the "improved" HVAC controls. The user can expect this set of controls to operate the air conditioning, heating, etc. Affordance, check! The controls are clearly marked and it is obvious what each of the buttons and dials will do. Visibility, check! Turn the dial up to increase the heat or down for lower cabin temperature. Mapping, check!