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10 Most Common Behavioral Biases

  
  Education
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I offer my list of Investors’ 10 Most Common Behavioral Biases.  There are a number of others, of course, and more will continue to be uncovered.  But I think that these are the key ones.  Your suggestions of important ones I have missed are welcome.

  1. Confirmation Bias. We like to think that we carefully gather and evaluate facts and data before coming to a conclusion.  But we don’t. Instead, we tend to suffer from confirmation bias and thus reach a conclusion first.  Only thereafter do we gather facts and see those facts in such a way as to support our pre-conceived conclusions.  When a conclusion fits with our desired narrative, so much the better, because narratives are crucial to how we make sense of reality.
  2. Optimism Bias.  This is a well-established bias in which someone’s subjective confidence in their judgments is reliably greater than their objective accuracy. Indeed, we live in an overconfident, Lake Wobegon world (“where all the women are strong, all the men are good-looking, and all the children are above average”).  We are only correct about 80% of the time when we are “99% sure.” Fully 94% of college professors believe they have above-average teaching skills (anyone who has gone to college will no doubt disagree with that). Since80% of drivers  say that their driving skills are above average, I guess none of them drive on the freeway when I do.  While 70% of high school students claim to have above-average leadership skills, only 2% say they are below average, no doubt taught by above average math teachers. In a truly terrifying survey result, 92% students said they were of good character and 79% said that their character was better than most people even though 27% of those same students admitted stealing from a store within the prior year and 60% said they had cheated on an exam. Venture capitalists are wildly overconfident in their estimations of how likely their potential ventures are either to succeed or fail. In a finding that pretty well sums things up, 85-90% of people think that the future will be more pleasant and less painful for them than for the average person.
  3. Loss Aversion. We are highly loss averse.  Empirical estimates find that losses are felt between two and two-and-a-half as strongly as gains.  Thus the disutility of losing $100 is at least twice the utility of gaining $100. Loss aversion favors inaction over action and the status quo over any alternatives. Therefore, when it comes time for us to act upon the facts and data we have gathered and the analysis we have undertaken about them, biases 2 and 3 – unjustified optimism and unreasonable risk aversion – conflict. As a consequence, we tend to make bold forecasts but timid choices.  (more…)

Baker & Nofsinger, eds., Behavioral Finance

  
  Education
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Behavioral Finance: Investors, Corporations, and Markets, edited by H. Kent Baker and John R. Nofsinger (Wiley, 2010) is a must-have book for anyone who wants a comprehensive review of the literature on behavioral finance. In thirty-six chapters academics from around the world write about the key concepts of behavioral finance, behavioral biases, behavioral aspects of asset pricing, behavioral corporate finance, investor behavior, and social influences. The book is hefty (757 pages of typographically dense text), and each contribution includes an extensive bibliography. But this is not simply a reference book; it reads surprisingly well.

Why should we study behavioral finance? “Anyone with a spouse, child, boss, or modicum of self-insight knows that the assumption of Homo economicus is false.” (p. 23) In our investing and trading—indeed, in all the financial decisions we make, we are prone to behavioral biases; we are often inconsistent in our choices. Only if we understand the kinds of emotional pulls that negatively affect our financial decisions can we begin to address them as problems. Some of the authors offer suggestions for overcoming these problems.

Here are a few takeaways from the book that give a sense of its tone and breadth.

First, I am happy to report that the literature shows that “high-IQ investors have better stock-picking abilities” than low-IQ investors and they “also appear more skillful because they incur lower transaction costs.” (p. 571) I figure that everyone reading this review falls into the Lake Wobegon category.

Second, individual investors can form powerful herds. “[T]rading by individuals is highly correlated and surprisingly persistent. …[I]ndividual investors tend to commit the same kind of behavioral biases at or around the same time [and hence] have the potential of aggregating. If this is the case, individual investors cannot be treated merely as noise traders but more like a giant institution in terms of their potential impact on the markets.” (p. 531)

Third, what are some of the behavioral factors affecting perceived risk? Although the author lists eleven factors, I’ll share just two. “Benefit: The more individuals perceive a benefit from a potential risky activity, the more accepting and less anxiety (fear) they feel…. Controllability: People undertake more risk when they perceive they are personally in control because they are more likely to trust their own abilities and skills….” (p. 139)

And finally, investors’ attitude toward risk is not fixed. They care about fluctuations in their wealth, not simply the total level. “[T]hey are much more sensitive to reductions in their wealth than to increases,” and “people are less risk averse after prior gains and more risk averse after prior losses.” (p. 355) Interestingly, CBOT traders tend to exhibit a different pattern, reducing risk in the afternoon if they’ve had a profitable morning.

As should be expected in this kind of volume, there is a fair amount of repetition. The same studies are quoted by several authors. We read about such topics as overconfidence and the disposition effect multiple times. The context is different, the principles are the same. But through repetition we come to appreciate the scope of behavioral finance (and often its limitations as well).

Although this book is certainly no primer, the reader needs only a passing familiarity with behavioral finance to profit from it. And for those who are better acquainted with the field, it is a useful compendium and an excellent research tool. It has earned a place in my library.

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