In the version I took, at any rate, it said something along the lines of "press the M key", "press the Z key" I remember thinking, "What an odd way of doing it". Easy to skim over it and understand it as "click the M button", since this is the normal behavior for a web survey. I wonder if they wanted you to be poised over the keyboard, since this was (as I recall) a speed-driven portion of the survey.