Monday, December 21, 2015

Confirmation Bias

I heard a commentator recently describe Americans as living in silos.  They get their news from their favorite source, and it is their favorite source because it tells them something they already believe.  They choose their friends based on how much they agree with them.  They “un-friend” those on social media who disagree with their own world view.  They just live in the silo where everything is peaceful and calm, where there is never conflict or disagreement, but where also there is no longer any growth or learning.  The point of the comment was politics, but these days everything is politicized and the comment can easily be extended to all aspects of life and daily decisions.  This activity of believing what is comfortable and consistent with current beliefs and rejecting or ignoring what is not, is known as confirmation bias.

Here is another example of the kind of information that will be accepted by some and rejected out of hand by others.  NBC reports that the European Food Safety Authority (EFSA) said glyphosate, the active ingredient in Roundup, was unlikely to cause cancer in humans.  Now policymakers in Europe must decide whether to extend the current approval period beyond the end of the year.  This comes while environmental groups have been calling for a ban and some businesses have begun to limit its use.  But the EFSA spokesman says:  "This has been an exhaustive process - a full assessment that has taken into account a wealth of new studies and data…unlikely that this substance is carcinogenic."

EFSA scientists worked with experts from EU member states and focused specifically on glyphosate, whereas the study supporting the environmentalists’ objections assessed groups of related chemicals.   Therefore, the findings of toxicity could be related to the other chemicals or some interaction. 

What is interesting in this case is that the EU is typically far less tolerant than the US when it comes to environmental issues, choosing to err on the side of extreme caution, for example their stance on GMOs.  Therefore, for them to make a statement exonerating (in a sense) Roundup is more significant than if it came from another source.  (This information is not inconsistent with my Master Gardener training which does not discourage the use of glyphosate, as long as it is used for the proper purpose according to the label instructions.)

Nevertheless, some groups will dismiss this report out of hand.  The great thing about confirmation bias is that it requires no evidence.  In fact when you disagree, evidence becomes a nuisance.

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