Denise Moore;
With all respect to those who think the pilots had to be to blame, it is not likely that three experienced pilots all made such errors unless the instrumentation and the way it presented information to them misled them.
Perception and logic are not necessarily good bedfellows.
A system designed to provide prior warning of a stall can and will fail when its warning is dealt with incorrectly. A bit like the original photovoltaic door guard; it told you when the beam was broken but didn't discriminate between someone entering or leaving.