Scientists in Zhejiang University in China just had a BREAKTHROUGH discovery on the psychology behind rock-paper-scissors.  Here's what they found . . .

1.  When a person's turn is successful, they'll most likely stick with what they chose for their next turn.  So if they beat you with rock, they'll probably try rock again the next turn.

2.  But if the person's turn ISN'T successful, they'll usually switch to whatever BEAT them.  So if they throw rock and lose to your paper, they'll switch to paper on their next turn, since paper beat them.

The researchers say that switch is a CONDITIONAL RESPONSE . . . it's something we do instinctively, even if we think we're just picking randomly. 

(MIT Technology Review)