We are in debt to our academic friends who work hard to verify the things that we believe to be the case from the evidence of our own behaviour. It is the sign of a pricing amateur to extrapolate our own behaviour onto the larger population!
In this case, our applause goes to: Feinberg, Richard A. (1986), “Credit cards as spending facilitating stimuli. A conditioning interpretation,” Journal of Consumer Research, 13 (3), 348–356 and updated further by Prelec, Dražen and Duncan I. Simester.
The research proves though that not only do we spend more freely with a card than with cash, but the effect is increased by the use of contactless. The research also shows that our ability to price discriminate also reduces when we pay by card. It is almost as though we regard card spending as less relevant to our wealth than cash.
Curiously, it has also been proven that this effect is limited to the physical world. Online, where everything is card-related, our attention returns to the subject of price and the more rigorous determination of value.
In the physical world go ‘card only’. You can desensitise your customers to the price of goods.