"Male mice of the C57BL/10 strain were defeated for 30-minute intervals every other day for varying periods, and were afterward given training which would cause normal animals to learn to fight . . ‥ After 4 to 6 days of defeat, most mice could not be trained to fight within a two-week period, and in two instances this effect persisted after two months of rest. It is concluded that a persistent inhibition of fighting behavior was developed by this means." (PsycINFO Database Record (c) 2006 APA, all rights reserved)