Red vs Blue Pen in Grading

Here is an interesting story heard in NPR’s All Thing Considered: “Red Ink May Lead To Lower Grades“

Here’s a brand new twist on the red-blue divide that has nothing to do with politics. California psychology professor Abraham Rutchick studied how people use red and blue pens to grade papers. He tells host Guy Raz that the red graders were way tougher than those who used blue pens.

Hmm… I use red pen so does that mean I’m more strict? There was a professor who also gave really high grades to students. I even got 99 as my final grade for Applied Mathematics. Wonder what kind of pen did he use to grade?