On September 11, 2001, the air was sizzling with anger — and the anger got hotter as the hours passed. That, anyway, was one finding of a 2010 analysis of 85,000 pager messages sent that day. The researchers employed a commonly used tool called Linguistic Inquiry and Word Count, or LIWC, which teases out information from the frequency of word usages in texts. But were Americans really so angry?