“…In particular, 2D:4D appears to be influenced by androgens: a more masculine digit ratio has been associated with CAH (Brown, Hines, Fane, & Breedlove, 2002;Okten, Kalyoncu, & Yaris, 2002, but see Buck, Williams, Hughes., & Acerini, 2003, as well as genetic predictor of androgen sensitivity (Manning, Bundred, Newton, & Flanagan, 2003). Because 2D:4D may reflect prenatal androgens, multiple studies have utilized this morphological marker to examine a possible role of early androgens on spatial ability (Alexander, 2005;Austin, Manning, McInroy, & Mathews, 2002;Coolican & Peters, 2003;Csatho, Karadi, & Kallai., 2005;Csatho et al, 2003;Kempel, Burk, & Hennig, 2005;Kempel, Gohlke et al, 2005;Loehlin, Luciano, Medland, & Martin, 2005;Manning & Taylor, 2001;McFadden & Schubel, 2003;Peters & Manning, 2005;Poulin, O'Connell, & Freeman, 2004;Putz, Gaulin, Sporter, & McBurney, 2004;Rahman, Wilson, & Abrahams, 2004;Sanders, Bereckzei, Csatho, & Manning, 2005;Scarbrough & Johnston, 2005;van Anders & Hampson, 2005). The results of these studies have also been quite variable, with some finding positive relationships, others finding negative relationships, and still others finding no significant relationship, even within a single sex (see Putz et al, 2004 for a partial review).…”