http://www.conversiondoctor.com/convers ... bandonment
I would be very interested to see a live test of this in action with other websites.
I don't think that in our days of tabbed browsing that visitors abandon to go coupon code hunting. I think there are other psychological factors involved here. Primarily, the concept that if the retailer is willing to offer a discount to whomever has the code, that I'm not getting the best price when I don't have the code. I think that customers want to feel that they are getting the best possible price every time. I think of it this way, if I walked up to the counter in a shoe store with my purchase and they said, "I could give you a lower price than this...up to 30% lower...but I won't!", I'm not sure how great I would feel about paying full price.
Again, it would be interesting to prove this out and see if it trends across more than one website.