Rats or mice that previously won a pushing contest have a higher probability of winning a subsequent contest.

“Now you take the winner, you give it a new competitor. And what you find is that the mouse or rat that won previously has a much higher than chance probability of winning the second time. In other words, winning before leads to winning again. And the reverse is also true. If you take the loser and you put that loser in with another mouse, fresh mouse, new mouse, the loser typically will lose at much greater probability than chance. And this is not related to differences in strength or size or testosterone or any other things that might leap to mind as explanations for this because those were all controlled for.”