We report a laboratory experiment that investigates the impact of passive participation on bubble formation in asset markets with inexperienced and experienced traders. Some treatments employ pre-market training in which each participant is 'matched' with a trader from a different prior market and observes all trading details but does not directly participate in trading. We find that passive participation, similar to direct experience, significantly reduces mispricing in subsequent markets. This finding suggests that observation of prices is a key mechanism through which experience mitigates bubbles. We also vary whether transaction prices are displayed in a column of text or in a graphical display, and find that among inexperienced and once-experienced traders, markets with the tabular display result in bubbles that are greater in amplitude relative to markets with the graphical display.