Brain Basics: Brain Damaged Investor from Inside the Investor's Brain by Richard L. Peterson

According to a 2005 Wall Street Journal article, "Lessons from the Brain-Damaged Investor," brain-damaged traders may have an advantage in the markets (1). Study participants who had a brain lesion that eliminated their ability to emotionally "feel" were compared against "normals" in an investment game. The chief researcher, Professor Baba Shiv (now at Stanford University), used a mixed sample of patients with damage in emotional centers including either the orbitofrontal cortex, the amygdala, or the insula.

In Shiv's experiment, each participant was given $20 to start. Participants were told that they would be making 20 rounds of investment decisions. In each round, they could decide to "invest" or "not invest." If they chose not to invest then they kept their dollar and proceeded to the next round. If they chose to invest, then the experimenter would first take the dollar bill from their hand and then flip a coin in plain view. If the coin landed heads, then the subject lost the dollar, but if it were tails, then $2.50 was awarded. On each round, participants had to decide first whether to invest. The expected gain of each dollar "investment" was $1.25 (average of $0 and $2.50), while each "not invest" decision led to a guaranteed $1. The expected value of the gamble being higher, it was always the most rational choice. Thus, one might assume that subjects always "invested" in order to make more money.

In fact, the results are not uniform. Normals (without brain damage) invested in 57.6 percent of the total rounds, while brain-damaged subjects invested 83.7 percent of the time. Many normal subjects (42.4 percent) were "irrationally" avoiding the investment option. Following an investment loss in the prior round, 40.7 percent of the normals and 85.2 percent of the patients invested in the subsequent round. After recent losses, normals invested 27 percent less often. They became even more "irrationally risk avoidant" after a loss.

Of the patients with different brain lesions, the insula-lesion patients showed the leas sensitivity to risk, investing in 91.3 percent of all the rounds and in 96.8 percent of the rounds following a loss. As a result, it appears that the insula is one of the most important drivers of risk aversion. Without an insula, brain-damaged patients were more likely to "invest."

On the lighter side, neurologist Antoine Bechara ventured that investors must be like "functional psychopaths" to avoid emotional influences in the markets. These individuals are either much better at controlling their emotions or perhaps don't experience emotions with the same intensity as others. According to Professor Shiv, many CEOs and top lawyers might also share this trait: "Being less emotional can help you in certain situations." (2)

1. "Lessons from the Brain-Damaged Investor" Wall Street Journal, July 21, 2005.
2. Chang, H.K. 2005. "Emotions can Negatively Impact Investment Decisions" (September). Stanford GSB.

Newton Linchen replies:

Larry Williams teaches that we shouldn't try to "improve" our personality regarding trading and emotions. There are "emotional guys" and there are "cold guys". Being an emotional type and trying to become cooler is another problem to solve, and the markets gives us already much trouble to work with. So, he says in his books that we should only recognize "what type" of people we are, and develop our trading style accordingly.

Pitt T. Maner III comments:

With the availability of more and more powerful software programs for the average Joe, will the human element eventually be less of a factor? One for instance can play a very mean game of chess without being a grandmaster by using a powerful program to suggest moves. There are tournaments where this is allowed—man/computer chess. http://en.wikipedia.org/wiki/Advanced_Chess So could it be that there will be a move towards very advanced "cyborgian" arrangements in the future. Not necessarily more profitable but less emotional–more algorithmic. It seems the younger generations are more trusting of technology to solve all problems, and as costs come down on the technology and software, will there be a pull to use methods similar to those now employed by professionals? Can one become competitive by using a "crutch"? Mr. Schnytzer noted a couple of years ago, " My guess is that with Deep Blue at your disposal, you'll beat Nigel easily at chess, but won't improve on your options trading profitability." Of course there is a company, however, using the Cyborg name that promises (for a small fee) to bring all this to the common investor…but does it work, or with increasingly advanced software can it work in the future? http://www.businessinsider.com/cyborg-trading-promises-hft-solutions-for-joe-trader-2009-11

Kim Zussman comments:

'We should only recognize "what type" of people we are, and develop our trading style accordingly.' Up to and including not trading. The idea that anyone can learn to trade successfully can be checked by asking yourself: 

1. Could you learn to play competitively right now in the NBA , NFL, or national league?

2. How long could you stay conscious in the boxing ring for your weight class, or with an opponent twice your size (SEC says no guns allowed)?

3. If trading can be taught, why do most fail?

4. If a scientist, by definition shouldn't you be too quick to abandon convictions, and therefore vig-out with overly-tight stops?

Rocky Humbert responds:

The answer to Kim's question #1 and #2, as posed, is self-evident.But there may be flaws in the question. No one can just walk onto a field and play pro ball. Likewise, no one can walk into an operating room and perform open heart surgery. However, must people can (assuming they are able-bodied and mentally capable) invest thousands of hours and achieve some reasonable level of proficiency in most activities. A reasonable level of proficiency, does not mean being Derek Jeter, Tiger Woods, Christian Barnard, Buffett, Soros, Steinhardt and Robertson. Fortunately, one does not have to be in the 99.999999% percentile to be deemed a non-failure — or almost every reader (myself included) of this email would be over-dosing on anti-depressants! On #3, Why is there any reason to think that the percentage of traders who fail is any more than the percentage of entrepreneurs who fail (90%), or the number of people who drop out of the 36-week Navy SEAL class (70+%)? Competitive, high-risk activities always have a high drop-out rate. But, most of these people find their calling and are productive members of society…even if they can't throw a 100mph fast ball.

Jeff Watson comments:

I've often wondered where that meme of a 90% failure rate in trading originated. I see it in the literature, and hear it repeated all the time, accepted as gospel. Has anyone actually done a study to quantify this, or is the number just one of those numbers like Mitch Snyder pulled out when he quipped that "10,000 homeless people die a day".. And, what constitutes success in trading, what time parameter. Is success measured by return, by amount made, or by the ability of someone to grind out a small profit for 30-40 years, solidly in the black but never making a fortune?

Rocky Humbert replies:

Jeff's statement: "Is success measured by return, by amount made, or by the ability of someone to grind out a small profit for 30-40 years, solidly in the black but never making a fortune?" are great first questions. Regarding traders "failing," one should also consider a related data point: According to the BLS, the "average" baby boomer held 10.8 jobs from ages 18 to 42. 23 percent held 15+ jobs, and only 14% held fewer than 4 jobs. So, the "average" person changes jobs every 2 years. If one defines trading as a "job," then someone who does this, sitting in the same chair, for a long time is quite unusual compared with the population. see : http://www.bls.gov/nls/y79r22jobsbyedu.pdf

Kim Zussman comments:

No one can just walk onto a field and play pro ball. Likewise, no one can walk into an operating room and perform open heart surgery. However, must people can (assuming they are able-bodied and mentally capable) invest thousands of hours and achieve some reasonable level of proficiency in most activities.> My question is based on evidence like the article; supporting geneticaspects to behaviour, ability, gifts, and handicaps. Not everyone canbe trained to reasonable proficiency in the big leagues - and marketsare by definition among the biggest. Shouldn't traders ask themselves whether the reward/risk compensates the opportunity cost of thousands of hours of (potentially pointless)learning, if one may be (unknowingly) missing abilities needed toexceed results of buy and hold?

Peter C. Earle comments:

I am quite sure that this particular figure - 90%, sometimes shifted to 95%or even 99% - originated firmly in the late 1990s, when the SEC went afterthe SOES shops. They took, as their core example of the dangers, the exampleof one office of a particular firm which in a short amount of time morphedinto a general representation of the daytrading business (e.g., even the'prop shops' which were less focused on commissions than profitable trading)and was ultimately extended through word of mouth and the nascentblogosphere (e.g. message board jabbering) to cover any intraday tradingdone (online brokerage accounts, the occasional one day open/close, etc),and has since grasped the received wisdom of the collective mind at thispoint to an extent that it goes unquestioned. The fact is, the SOES traders/daytraders (as my man Lack will no doubtattest to) were mostly undercapitalized, out-of-work accountants andconstruction workers being sold 'maps to the gold mine', as it were. A better statistic, to start with, would be: with an $X account, after twelve months, how many remained?

Kim Zussman comments:

Interestingly, the author was as irrational as his subjects byfollowing the academic herd, making a low-risk, incorrect conclusion: "This study is especially relevant because of a concept called the"equity premium puzzle" that has long bemused financial experts. Theterm refers to the large number of individuals who prefer to invest inbonds rather than stocks, even though stocks have historicallyprovided a much higher rate of return. According to Shiv, there iswidespread evidence that when the stock market starts to decline,people shift their retirement savings—that is, their long-term, notshort-term, investments—from stocks to bonds. "Whereas all researchsuggests that, even after taking into account fluctuations in themarket, overall people are better off investing in stocks in the longterm," said Shiv. "Investors are not behaving in their own bestfinancial interest. Something is going on that can't be explainedlogically." This study, 2005, was in the middle of a decade where bondsout-performed stocks, and the irrationally risk-averse were punishedby missing out on ruin.


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