| − | |correlated with intelligence, the attention span is how long someone can concentrate on something. It is rapidly shortening; the Lincoln-Douglas debates of 150 hours ago lasted for hours, but none do today.<ref>http://www.help4teachers.com/ras.htm</ref> | + | |correlated with intelligence, the attention span is how long someone can concentrate on something. It is rapidly shortening; the Lincoln-Douglas debates 150 years ago lasted for hours, but none do today.<ref>http://www.help4teachers.com/ras.htm</ref> |