This EJP paper is open access, so you should be able to read it. The conclusion isn't unexpected, because having a "scaffolding" to guide a student through a problem is almost like hand-holding without an instructor being there. I've used this type of questions during quizzes and maybe even midterm. But for the finals, where the students must demonstrate a command of the material to get good scores or grades, I drop the scaffolding. Zz.