Choi's analysis affirms earlier studies. Richard Thaler and Cass Sunstein address several fiduciary concerns regarding 401(k) plan enrollment in their 2008 book, Nudge. Using the framework of behavioral economics, the authors both cite exams and offer recommendations that might help 401(k) plan sponsors better help their employees.

The basic notion of Thaler and Sunstein holds will defer making hard decisions – and investing for one's retirement just happens to be among life's most difficult decisions for most people. Think about it. To appropriately invest one's 401(k) assets, the employee must enjoy working on somewhat complicated mathematical scenarios, must have the commitment to faithfully implement any decision and must not be distracted by adult toys, pop culture and screaming kids. Easy, right?

Not so, say Thaler and Sunstein. In fact, the authors feel it's more reasonable to assume employees more likely will not make the correct decision (we're not merely talking about what to invest in, we're talking about savings in the first place). Now consider this. If a plan is designed in a manner that dissuades employees from making correct decisions, and there exists other plan designs that actually encourage employees to make the correct decision, on who's shoulders does this dereliction of fiduciary duty fall upon? This is why plan sponsors need to pay attention.

The authors suggest two things. First, they whole-heartedly advocate auto-enrollment programs with a limited number of default options – and not necessarily the "balanced" or "target-date" options required by the DOL. Second, they present a program they call the "Save More Tomorrow" program. In it, employees automatically start saving at a small percentage rate of their salary and that percentage increases every time the employee receives a raise.

For example, all employees would be automatically enrolled in a single default investment option – a mutual fund with a goal-oriented target of an 8% average annual long-term return (this would eliminate target-date funds since we're targeting the return, not the retirement date). The 8 percent target, although it seems high by today's standards, does reflect a reasonable equity return for a 30-year period (the time period which 20-year olds have until retirement and 65-year olds have as a remaining life expectancy). The 8 percent target also represents the reasonably conservative return requirement to build retirement assets. Remember, we're only talking about the default option here – employees would always have the option of choosing other options within the plan. Automatic salary deferrals would start at 6 percent (assuming the company matches up to that amount) and 25% of every raise would go towards increasing the deferral rate.

Over time, adopting this sort of SMT policy will help plan sponsors help employees. Of course, we'd have to convince the DOL to rethink its default option rules.