Wendy A. Kellogg Thomas Erickson Tracee Vetting Wolf Stephen Levy Jim Christensen Jeremy B. Sussman William E. Bennett Leveraging digital backchannels to enhance user experience in electronically mediated communication. 451-454 2006 conf/cscw/2006 CSCW http://doi.acm.org/10.1145/1180875.1180943 db/conf/cscw/cscw2006.html#KelloggEWLCSB06