Super-exponential bubbles in lab experiments: evidence for anchoring   over-optimistic expectations on price
  We analyze a controlled price formation experiment in the laboratory that shows evidence for bubbles. We calibrate two models that demonstrate with high statistical significance that these laboratory bubbles have a tendency to grow faster than exponential due to positive feedback. We show that the positive feedback operates by traders continuously upgrading their over-optimistic expectations of future returns based on past prices rather than on realized returns. 
Andreas H\"usler, Didier Sornette, Cars H. Hommes
q-fin.TR