A number of anti-Monsanto, anti-biotech groups and activists have pushed the notion that consumers “have the right to know” if the food they consume contains ingredients from genetically-modified crops. For the most part the agriculture industry – minus some, but not necessarily all, organic producers and groups – have opposed this concept based on the likelihood that it would increase cost, has zero benefit to the consumer given that GMO ingredients are nutritionally identical to non-GMO ingredients, and also based on the fear that such labels would be akin to the warning labels required on cigarette packages.

Some recent research suggests those of us opposed to mandatory labeling may have been a bit irrational in our opposition.

Purdue University ag economist Jayson Lusk and colleague Jane Kolodinsky from the University of Vermont recently published a paper in which they found opposition to GMOs in Vermont actually dropped relative to opposition in the rest of the country after mandatory labeling was adopted in that state.

At his blog, Lusk notes that several years ago, he was “decidedly in the camp that thought imposition of mandatory labels would cause people to be more concerned about GMOs because it would signal that something was unsafe about the technology.”

Prominent scholars such as Cass Sunstein have argued the same.  A few years ago, Marco Costanigro and I put this hypothesis to the test in a paper published by Food Policy, and we found little evidence (in a series of survey-based experiments) that the label per se neither increased or decreased aversion to GMOs.  So, I was less convinced that this particular argument against mandatory GMO labeling was valid, but I was still unsure.

Last summer, however, Kolodinsky published research that changed his mind. “Her data suggested opposition to GMOs fell at faster rate after mandatory labels were in place,” he wrote. “Despite my findings in Food Policy, I remained dubious and Jane and I went back and forth a bit on the robustness of her findings.”

The two researchers set aside philosophical differences on GMOs to test actual consumer preferences relative to GMOs based on labeling. Their research found something quite interesting, and perhaps counterintuitive.

“This research aims to help resolve this issue using a data set containing more than 7800 observations that measures levels of opposition in a national control group compared to levels in Vermont, the only U.S. state to have implemented mandatory labeling of GE foods. Difference-in-difference estimates of opposition to GE food before and after mandatory labeling show that the labeling policy led to a 19% reduction in opposition to GE food. The findings help provide insights into the psychology of consumers’ risk perceptions that can be used in communicating the benefits and risks of genetic engineering technology to the public.”

Lusk noted that this result “does NOT suggest people will suddenly support GMOs once mandatory labels in place.” Lusk reiterates that mandatory labels may still cause economic harm – but they may not, either.

The concerns over mandatory labels appearing as a type of Surgeon General’s Warning for GMOs aren’t exactly unfounded. Some years ago, the Freakonomics Radio podcast covered ways to make people quite smoking, and they found an M.I.T. study of tobacco control in Uruguay which held that graphic, grotesque imagery on a cigarette package had a significant effect on smoking cessation.

That is not to say that GMO labels on food would be “graphic, grotesque imagery,” but certainly that is at the extreme end of what pro-GMO factions fear with regard to labeling: that labeling is intended to warn consumers away from modern food technology.

Lusk makes a strong case by working with someone who holds a different set of priors and biases, and reexamining his own priors and biases, that we not only have to be aware of our own blinds spots, but that we should actively test our beliefs and conclusions to make sure that we aren’t actually full of wind.

One study doesn’t settle the economic questions at the heart of the GMO labeling discussion, but the bigger point about things we know, and things we know that just aren’t so, is perhaps even more important.