At Grayson and Michael’s work there are two types of reports…

At Grayson and Michael’s work there are two types of reports (TPS and PGS) that they have to do, but nobody enjoys doing them. Grayson is really struggling trying to get his employee, Michael, to learn how to correctly file a TPS report. Grayson decides that every two times Michael incorrectly files a TPS report, Michael will have to fill out a PGS report as well. Which form of reinforcement is Grayson using?