When I give A’s, students are happier and complain less, I get to feel like a nice person, and I give my own students (whom I generally have somewhat warm feelings toward) a benefit in their future lives….
I remember looking at grading records for undergraduate classes back when I taught at Berkeley in the early 1990s. There was lots of variation in average grades by instructor, even for different sections of the same class. I didn’t do a formal study, but I remember when flipping through the sheets that average grade seemed to be correlated with niceness. The profs who were generally pleasant people tended to give lots of A’s, while the jerks were giving lower grades.
More here with an interesting discussion about grade inflation. Via MR.