12 Cognitive Biases That Endanger Investors
What you don't know can impact performance.
I recently came across a terrific article that addressed 12 cognitive biases that prevent human beings from behaving rationally. As perception is reality in the financial markets, I thought it might be useful to address those issues through the lens of a trader.
1. Confirmation Bias
This is a fatal flaw of trading; we tend to surround ourselves with information that validates our own point of view and dismiss input that conflicts with our reasoning (also known as cognitive dissonance). This is the primary reason why we always strive to see "both sides of every trade" as the residual grist between variant views is where education-and profitability-resides.
2. In-Group Bias
This is a manifestation of confirmation bias, or the tendency to surround ourselves with those who share similar takes on the tape. This could pertain to our physical environment or a virtual experience, such as Twitter. Not only does this provide a false sense of security in our individual viewpoints, it makes us suspicious-or angry-with outsiders who dare to question how we feel. (See also: The Gold Scold.)
3. Gambler's Fallacy
One of the most famous disclaimers in finance is that past performance is no guarantee of future results. This bias is often referred to as a "glitch" in our thinking in that it extrapolates what happened in the past to construct an idea of what will happen the future. How many of you have played roulette at a casino under the premise that a string of red increases the likelihood of a black outcome? That's flawed thinking; the odds of red (or black, for that matter) or 48% on each independent spin.
4. Post-Purchase Rationalization
One of our Ten Trading Commandments is that the definition of an investment should never be a trade gone awry. Nobody initiates market exposure expecting to lose money, but we should never post-rationalize our risk (such as ignoring stop-losses or throwing good money after bad). We would be wise to remember that good traders know how to make money but great traders know how to take a loss.
5. Neglecting Probability
History is littered with stretches where in hindsight we're reminded not to confuse brains with a bull market. This bias limits our ability to properly assess risk, whether it's overstating an unlikely event (such as buying a stock for a takeover) or understating an unlikely event (such as Y2K, the fiscal cliff, or a terrorist attack). Tail events do happen, of course, but betting on an outlier is a long shot by its very definition.
6. Observational Selection Bias
This is when we suddenly notice something we haven't noticed before, and wrongly assume the frequency has increased (when it hasn't). Let's say I bought cannabis stocks as a way to play (what I perceive to be) the legalization of marijuana. All of a sudden, everywhere I look, there are more and more signs that support my thesis; the topic is featured on 60 Minutes, it's a hot-button issue during the election, it gained momentum in the mainstream media. While some of that may prove true, I am on the lookout for news, whether it's conscious or not.
Todd Harrison is the founder and Chief Executive Officer of Minyanville. Prior to his current role, Mr. Harrison was President and head trader at a $400 million dollar New York-based hedge fund. Todd welcomes your comments and/or feedback at firstname.lastname@example.org.
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