Types: "...the accessibility of information stored in memory (Dunlosky& Nelson, 1994), ease of recall (Mazzoni& Nelson, 1995), cue familiarity (Reder, 1987), retrieval fluency (Benjamin & Bjork, 1996), topic knowledge (Hacker et al., 2000), type of test item (Bol & Hacker,2001), item difficulty (Schraw & Roedel, 1994), inferential processing (Koriat, 1997), and study conditions (Dunlosky & Nelson, 1994) (Hacker and Bol, 2004)."