I have a variety of reactions to this study ... ranging from "WTF?" to "sigh ...". I'd like to think that my students believe that their grade depends upon performance, not effort. Of course, lack of effort often leads to poor performance.
Hm. Maybe we're dealing with a simple logical fallacy here. "Lack of effort leads to poor performance" is not logically equivalent to
"Good effort leads to good performance." (Funny how often that discrete math stuff comes in handy.)