[GravelRocks]

I assure you there are people that haven't decided how to pay for something before they reach the register. There's also a lot of people that will decide how to pay for something based on how much the purchase is at the register. Both of those examples are anecdotal, and come from working a register some decade and a half ago. Anecdotally, I bring cash with me when I go on vacation. I never really thought about it so much as guilt, but you could probably characterize it somewhat as that. It's at least done partially for budgetary reasons, but I'm sure subconsciously I really don't want to remember spending $80 at the Tiki bar.

As for the reproducibility it looks like, from the article, that they at least constructed several simular studies to test their theory:

1. "In one study, the authors analyzed more than 118,000 real-world purchases at the Stanford University Bookstore."

2. "Another study asked participants to imagine buying a 30-minute reiki session. Half read that the session was recommended by their doctor and would be at a hospital..."

3. "Another study explored shoppers’ preference for untraceable payment methods besides cash. Half the participants were informed they had a $20 bill and a debit card linked to their bank account; the other half were told they had a $20 bill and a prepaid debit card."

It's at least not a single, "3 grad students did this in an afternoon at the 7-11" study that tend to get picked up. I don't doubt that more research into the phenomenon might help get a better understanding of the underlying motivations for "cash/credit", but it does look like they are getting similar results from multiple experiments.