A greater number chose the 1% rate in the first test than chose the 0% rate in the second test.
The JCR suggests that comparing 20 to 0 is harder for most people than comparing 20 to 1. Maybe. Or, maybe 1% is more credible. (That was the thinking behind claiming that Tab cola had only 1 calorie, when in fact it had none.) But of course, why more people chose 1% is a matter of speculation. It’s easier to ferret out what people do than why they do it.
The JCR goes on to suggest that if you’re competing with a bank that offers a card with a 20% interest rate, you’ll be better off going up against them with a 1% than with a 0% card. Maybe. Trouble is, their test doesn’t represent the real world — where not just two, but multiple offers exist and compete. Plus, you should be wary of putting stock in a “what would you do” test. When people act, they often do the opposite of what they predicted they would do.
For best results, test in the real world, where real people act in earnest, unaware that a test is afoot. Asking “what would you do?” is not a bad way to learn how people view themselves. But it’s a terrible way to predict behavior.