The first chapter of the Bernie Madoff fiasco has come to a close, with Madoff pleading guilty to 11 charges of fraud yesterday.

Madoff’s massive Ponzi scheme was horrific on many levels. But while we watch the next phase of the scandal, it’s important to ask: What lessons are we going to learn from this? I can see three lessons that relate to my work studying human irrationality — and in particular, some non-useful lessons we might learn.

One lesson that individuals and foundations are likely to take from the Madoff scandal is that in addition to diversifying their portfolio across several investments (stock, bonds, equity, cash), they also need to diversify their investments among several advisors. While the idea of diversifying among advisors has some merit — and it could reduce the exposure risk of another Madoff scandal — it will also make the task of managing portfolios much more difficult and much less efficient. Imagine that you have $1,000,000, split among four advisors. You will need a whole new level of coordination among them so they can have the right amount of cash, bonds, stocks etc., across all of your assets.

And I think that people will begin to over-diversify across investors. Why? Because when we have one large and salient instance in our minds, it can be so powerful that we overemphasize it. This same effect is very apparent in what we call “the identifiable victim effect,” and it is the reason that we overemphasize the risks of a shark attack, and underestimate the risks of riding a bike without a helmet. In general, what we find when there’s one single vivid event is that people overweight it — we focus on it too much. So that’s the first lesson: We’re going to learn from the Madoff scandal, but we are going to overdo it.

Another non-useful lesson that I think we will adopt is to start searching with more vigor for other bad apples. On one hand, it is clearly important to prevent more Madoffs, but at the same time I worry that as a consequence of searching for bad apples, we won’t pay enough attention to other financial behavior that might not be as badly wrong but that can actually have larger financial consequences.

In our research on dishonesty, we found that when we give people the opportunity to cheat, many of them cheat by a little bit, while very few cheat by a lot. In our experiments, we lost about $100 to the few people who cheated a lot — but lost thousands of dollars to the many people who each cheated by a bit. I suspect that this is a good reflection of cheating in the stock market, where the real financial cost of the egregious cheating by Madoff is actually a tiny fraction of all the “small” cheating carried out by “good” bankers.

The risk here is that if we pay too much attention to chasing bad apples, we might pay too little attention to the situations where the small dishonesties of many people can have large consequences (such as paying slightly higher salaries to cronies, making small changes to financial reports, doctoring documents, being slightly dishonest about mortgage terms), and in the process neglect the real economic source of the trouble we are in.

A third bad lesson that I think people will take from this concerns the way we define acceptable levels of cheating. In a study that may parallel Madoff’s egregious dishonesty, we again gave the participants the opportunity to cheat, while solving a puzzle quiz — but this time we hired an actor. This actor, posing as a fellow participant, stood up at the start of the session and declared that he had solved all the puzzles. Now the question is how his behavior would influence the other participants in the room — the ones who were watching him.

What we found is that when the actor wore a plain T-shirt, which made him part of the student group, cheating increased. On the other hand, when the actor wore a T-shirt of the rivaling university, cheating decreased. What this means is that when someone who is part of our own social group cheats, we find it more acceptable to cheat, but when people who are not part of our social group cheat, we want to distance ourselves from these people and cheat less.

Madoff was part of the financial elite — part of an in-group of our financial leaders. Think of all these people who were in his house, who knew him well. So now, when other people in this circle see him cheating, think about the long-term consequences: Would these other people in this financial industry now be more likely to take the immoral path? It doesn’t have to be another Ponzi scheme. It just means that, now that they have been exposed to this extreme level of dishonesty, they might adopt slightly lower moral scruples. Maybe they will start not letting their clients know exactly what they own and what they don’t own, or change a little bit the interest rate that they’re charging them … I don’t think that those in his circle will necessarily become more Madoff-like people, but I do suspect that they will get a substantial relief from their moral shackles. Sadly, that’s his legacy.

So, Chapter One of the Madoff scandal is over, but I worry that the negative downstream consequences of this experience are just starting …