When filling out forms of various kinds, you would find it easier to be honest if you were asked to sign at the top rather than the bottom. When you sign at the bottom you’ve already stated whatever lies you’re going to tell.
But if you sign at the top, you’re burdened from the beginning by the moral weight of your pledge to be honest. This theory has been tested by having twenty thousand subjects fill out automobile insurance forms that they thought were real.
On the forms, clients were asked what their mileage was. Lower mileage got them lower premiums. Half the clients were asked to sign at the top; the other half were asked to sign at the bottom.
The theory was proved correct.
Source: Dan Ariely: Why we lie: the honest truth about dishonesty, Atlantic Online, May 29

I find it easier not to lie as I cannot remember all the untruths that I have uttered.
My condition is worse. I cannot remember the truths.
Ariely teases us with one way of making it easier to be honest. I wonder what he thinks are other ways. Anyway, is honesty a concept that is related only to truth?
I suppose one has to read his book. The word honesty suggests a connection with honour. Can I be honourable and untruthful?
Perhaps not but my point and my question is whether one cannot be truthful and still be dishonest. Is a truthful thief an oxymoron?
Robin Hood was an honorable thief and when he confessed (if he did – I don’t remember) was truthful.