Are you influenced by a free gift?

I have never suffered from allergies.  But lately, I have had a few sniffles that I can’t explain any other way.  Being new to the allergy game, I have no idea what med to try, or even what criteria I should use to choose. 

Wonder of wonders, BzzAgent and Claritin came to the rescue.  In exchange for reviewing their Claritin-D product, they were nice enough to send me a free supply.  Since it goes through BzzAgent and not directly from Claritin, there is not even a hint of a quid pro quo.  If you are familiar with BzzAgent you will know that they have a very peppy and positive brand image, but they are careful not to suggest that positive reviews get you more rewards or samples.  It is purely based on volume.  Posting the review on my blog, on BzzAgent’s site, on Claritin’s site, tweeting it, facebooking it, etc all earn me points.  And they “remind” me quite frequently to do so. 

So here is my question today.  Even though there are no extrinsic benefits of skewing my review positive, is there an unconscious bias?  Many studies have shown that we have an instinctive social need to reciprocate when we get a spontaneous, no-strings-attached reward.  This has been shown in pure economic contexts such as the Ultimatum Game and more nuanced contexts such as anonymously walking down the street.  In fact, many studies have shown a stronger need to reciprocate when the reward has no strings attached than when it requires payback. 

Just this weekend, there was a pay-it-forward chain of 378 people at a Starbucks in Florida (in Florida!) until a woman from out of town broke it.  The fact that the chain was broken by someone from out of town is actually important.  The closer we feel to someone, the more powerfully we feel the urge to reciprocate.  This has been found with similarities in career (“Hey, you’re a physicist too?  Let me buy you a beer!), education (“You went to Michigan too?  Let me buy you a beer!), race, religion, and where you live.  Even very subtle things like being assigned to the same team in a 15-minute psychology experiment that is ostensible about something else can induce it.

A fantastic study by Dan Ariely (or at least I read about it in his book) found that when you admit your potential bias, you are even more likely to be biased.  In this study, financial advisors who revealed that they were being paid to promote an investment were more likely to promote it.  The hypothesis is that the admission frees you from any guilt about it, so your urge to reciprocate gets unleashed.

So will my review of Claritin-D be skewed positively because I got the free sample, even though it was through a third party and there is no quid pro quo?  Since the effect is largely unconscious, I won’t ever really know for sure.  The only way to really know would be a double blind study with some carefully constructed control groups.  Especially since relief from allergy symptoms is highly subjective.  

Thoughts?