Confirmation Bias, The Investor’s Curse
by ilene - January 30th, 2010 5:33 pm
Confirmation Bias, The Investor’s Curse
Courtesy of Tim at The Psy-Fi Blog
Clinging to the Wreckage of Old Ideas
The problem of confirmation bias – the tendency of people to seek evidence confirming an already held opinion and to avoid looking for that which might upset their carefully constructed mental models has attracted a lot of attention from researchers. It occurs across all domains of human endeavour and triggers all sorts of implausible behaviour, yet investors and institutions remain in its thrall.
We find examples in law courts and doctor’s surgeries, in scientist’s laboratories and the lairs of legislators. So we shouldn’t be surprised to find it coursing through the veins of economists and investors, colouring their every thought and structuring their every idea. Of course a rational market participant, faced with a theory built on a crumbling cornerstone will abandon their ideas and look for some new ones. As you’d expect, therefore, we do no such thing, clinging irrationally to the wreckage of our dreams as they collapse around us.
Disconfirming Science
Science is perhaps the area in which we might expect confirmation bias to be least effective. After all, the processes of science are built around the institutionalisation of disconfirmation. New ideas have to run the gamut of envious colleagues who generally hate nothing more than a smart ass and take great pleasure in proving them wrong. Despite this scientists have generally proven remarkably reluctant to give up discredited theories. Indeed science has often proceeded for decades on the basis of ideas that could easily have been disconfirmed had anyone been sufficiently motivated to do so.
So, for instance, the idea that the universe is stable and unchanging was held way into the twentieth century despite the fact that Newton’s laws of gravitation implied something different. To be precise, they suggested that unless the universe was actually expanding gravity should be causing all the bits of matter in the cosmos to hurtle together towards a central point in a manner calculated to render discussions of globalisation, polar bear populations and national debt levels redundant. Yet when Einstein’s theories also predicted an expanding universe he simply made up a special constant, which he later had to ruefully remove, to stop this unwanted behaviour so ingrained was the…
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Philip R. Davis is a founder Phil's Stock World, a stock and options trading site that teaches the art of options trading to newcomers and devises advanced strategies for expert traders...
Ilene is editor and affiliate program
coordinator for PSW. She manages the site