A couple of things are at play in this experiment. The professor created a very scarce item. If the participants are fans, that would certainly drive both cash and credit card bidding on the price of the tickets. How much cash was available or limited? Did the professor give any indication on bringing cash to the silent auction? Where there real tickets to be won?

In this day and age of thoughtful purchasing, the idea that purchasing experiences over things have more meaning. So if the person who bid more on his credit card and payed it off at the end of the month maybe ahead of the credit card company. If the silent auction was part of a fundraiser for a nonprofit, the savvy winner would list his donation on his taxes as a deduction.

Depending on the credit card, that winner may even get valuable points for hotels or travel (when we can).