They use a separate but related experiment to determine if this "market experience" makes their subjects more rational, and conclude it does. The evidence seems to confirm this, but the effect is so small that I doubt it can be consistently replicated.
The canonical theory of consumer choice is a wonderfully flexible thing. It can be interpreted in such a way that it covers any conceivable behavior. The problem is that these interpretations empty it of content. It becomes a mere tautology, explaining nothing. I'm afraid that this paper is in the spirit of these tautological constructions of economics.