This
picture shows the driver's seat control in a car
we rented. The way it works is that you grab
the knob and pull in the direction of the arrow.
A rod "telescopes" out. Then you can move the
rod forward or backward like a lever to lower
or raise the front of the seat. I had to
play around with it for a while to figure out
how to work it. It is physically hard to move the
lever forward unless you are sitting in the
seat because your weight is used to lower the
seat. On the other hand, it is hard to figure
out how to work the control unless you are
outside the car looking at the control. It
is kind of a paradox. You can't easily use the control
unless you are sitting down and you can't easily see
the control unless you are standing up.
Design suggestion
When
you design a control, make sure you
can figure out how to use it from
the position you will be in when
you use it.