UNTIL THE TWELFTH OF NEVER http://www.gamasutra.com/features/20010427/hopson_02.htm This site gives information on how to get players to play games forever, using various schedules of reinforcement.
AAAAAPROACH OR AAAAAVOID? http://www.stammering.org/approach-avoidance.html This article written by a person who stammers argues that stammering is a result of an approach-avoidance conflict.
DISSERTATION FOR DESSERT http://web.utk.edu/~wverplan/biblio01.html This link is to the Ph.D. dissertation of William S. Verplanck. Read it and then use the links on his home page to find out more about him and other psychology-related links.
TRIAL AND ERROR, OR AHA! http://www.pigeon.psy.tufts.edu/psych26/spence.htm This link is to a page with an excerpt from Kenneth Spence's paper "Gradual versus Sudden Solution of Discrimination Problems by Chimpanzees," which was published in the Journal of Comparative Psychology, 1938, 213-224.