Further reading on the topic

http://www.di.uniba.it/intint/UM05/WS-UM05.html

http://www.scribd.com/doc/7753203/Age-as-an-Affective-Factor-in-Second-Language-Acquisition

http://www.supercamp.com/links/student-attitude-motivation-------------------------.html

http://www.nadasisland.com/motivation/