Many people find driving a trailer in reverse difficult. Most driving instructors will tell you the concept that is so hard for many people to learn is that, in order to make a trailer go left in reverse, you must turn the steering wheel to the right (and vice versa). This simply stumps us. In a day and age when most of us can pick up a new cell phone and figure out how to use it in a manner of minutes, why does it take people such a long time to learn how to a turn a trailer in reverse? The delay is probably related to a psychological phenomenon known as the Simon effect, which is the tendency to associate responses on the right with movements on the right, and responses on the left with movements on the left. When driving a trailer forwards, this works perfectly well, but in reverse we have to unlearn this pattern and do the opposite of what our instincts tell us to do. In the following experiment, you will see the relationship between spatial location and response selection.