They say there are two kinds of people in the world: Those who believe there are two kinds of people in the world and those who don’t.

What this little joke reveals is a truth that has helped practitioners of the psychological and philosophical arts for centuries. It’s called the dichotomy test. I’ve actually used it successfully to help people discover the meaning of their life, but I’ll leave that and my uncanny ability to interpret dreams for another time. This is about getting 401(k) investors to do the right thing.

The financial world is replete with dichotomies. For example, there’s bulls and bears; fear and greed; and, stocks and bonds. We all know (or should know) the most important thing a 401(k) investor can do to increase the odds of living a happy retirement: save more. Yet we repeatedly see employees not acting in their own best interests. How do we motivate these folks to save more?

That’s where this week’s dichotomy test comes in. Which do you believe is more likely to inspire 401(k) investors to save more: A list of Dos or a list of Don’ts.

(To participate in this test, first read “7 Simple Saving Secrets Every 401k Investor Should Know” and then read “The Ten ‘Don’t’s of 401k Investing.” You can wait to read them until you’re done with this article.)

For now, consider this story.

When I was in fifth grade, our teacher often would let us go outside and play kickball if we got our work done early. Sometimes, in the anticipation of the event, a classmate would ask, a bit prematurely, “Are you going to let us go out and play kickball?”

My teacher would invariably respond, “By asking me, you just gave me a million reasons to say, ‘no.’”

Some people rebel at the thought of being told what to do. This is usually the standard modus operandi for children going through a certain age. You know what I mean. If you want a kid to do something, tell him to do the opposite. I’ve heard people call this “child psychology” or “reverse psychology.” This behavior pattern disappears as we grow older and discover the folly of predictable rebellion. Still, some adults retain a vestige of this and prefer not to be told what to do.

Despite this aversion, most adults do exhibit a self-preservational urge that elevates the importance of knowing what could be harmful to them. This allows them to regularly avoid these dangers. (Who knows? It might be that most adults have this tendency because those that didn’t never survived into adulthood.) For these people, a list of don’ts takes on far greater importance than a list of dos.

Another way to look at this is to overlay the classic fear and greed dichotomy on top of it. One might say those motivated by fear are more likely to abide by a list of don’ts, while those motivated by greed will take more kindly to a list of do’s. The beauty of this debate is that there’s no reason to limit yourself to one type of list or another. If you’re working with a typical 401(k) plan, you’ll have a number of employees who’ll need to be motivated. Some will be motivated by do’s. Some will be motivated by don’ts. You don’t need a PhD in psychology because you don’t need to know which list motivates which people. Use both. The employees will decide for themselves which they prefer.

So take a look at the two articles referenced earlier. Read them both. Which article did you personally find more motivating? Is that consistent with your general preference for dos and don’ts list? Share your answers in the comment section below. Do it or don’t not do it. It doesn’t matter to me. You get to pick your own poison.

For more from Chris Carosa, see: