In studies involving genuine transactions of potentially high value we show that willingness-to-pay can be increased when customers are instructed to use a credit card rather than cash. The effect may be large (up to 100%) and it appears unlikely that it arises due solely to liquidity constraints. In addition to demonstrating the effect, we provide a methodology for detecting it, and our findings suggest a source of variance to test alternative explanations.
Prelec, D., &Simester, D. (2001). Always leave home without it: A further investigation of the credit-card effect on willingness to pay. Marketing letters, 12(1), 5-12.