Quote - ...When I went to school it was always feet and inches.
We also worked in pints and gallons, not litres.
I even look at the Farenheit side of my thermometer, not Centigrade...

Since I'm in the U.S., I automatically comprehend measurements in feet, inches, etc. It is so ingrained in me that I perceive those measurements based on visual associations.

If you say "6 ft.", for instance, I immediately think of the height of my father.

It's only when something is told to me in meters or litres that I have to do mental calcuations. :P