Fishtomatoes and the `backfire effect`

Early in 2015 a story started circulating on social media about a young man dying from an allergic reaction to eating a genetically modified tomato.  The source of the story,  World News Daily Report, claimed that a young Spanish man named Juan Pedro Ramos died after eating a tomato ‘containing fish genes’.  He was ‘known to have allergies’ but did not recover following the injection of epinephrine, and died later in hospital.


The idea of the ‘fishtomato’ has origins in fact; over a decade ago a company did try to put a fish gene into a tomato (Schmidt 2005).  However, the demise of Juan Pedro Ramos as told here is almost certainly not true.  No reputable news source reported this story, and I can’t find evidence of fish-tomato hybrids on the market in Europe or anywhere.

Nevertheless, it is not easy to prove that the story is untrue; I can’t find evidence for the absence of this (or most) events, I can merely fail to find the evidence and assume that it must not have happened.  This is a familiar epistemological challenge: it is hard (and perhaps impossible) to disprove a specific claim of an event after the fact.  I can go to all the hospitals, survey all the death records and interview every family member of every Juan Pedro Ramos in Spain, but even after finding no evidence that this event took place, I still can’t know with certainty that the story is a fabrication.

Normally this isn’t a big deal.  There are few certainties in life; more often than not we  decide what is ‘true’ and ‘false’ by weighing the balance of evidence, not by knowing anything with 100% certainty.  Unfortunately, as we all know (and as I’ve pointed out in my own example), the internet makes the spreading of false information very easy, and the sheer volume of falsehoods makes decision making based on evidence increasingly difficult.

A multiplier of concern is that once a person formulates a belief based on false evidence, corrections may not only fail to change their mind, but could actually reinforce their belief in falsehood.  In 2010 Brendan Neyhan and Jason Reifler published a paper called When Corrections Fail: The persistence of political misperceptions in which they study the relationship between belief, information and ideology.  Basically, they wanted to know if being presented with a correction of a currently held misperception of a political or economic fact would correct that misperception.  Perhaps unsurprisingly, they found that people with the strongest beliefs most resisted correction of those beliefs, and even worse, would develop a stronger attachment to their misperceptions when presented with facts pointing to the contrary.  This is the ‘backfire effect’, where attempts to change minds with good evidence accomplishes the precise opposite.

So these fishtomato stories are not only problematic because they are plentiful and false, but because they nurture a belief that is hard to reverse even in the face of clear facts to the contrary.  There are almost certainly thousands if not millions of people around the world that have come across this story, and some of these people now believe that there are fish tomatoes in their grocery stores.  And if any of those people read this blog post, they are almost certainly not going to be convinced to change their mind…