"It's not about applying pressure," Smith explained during her breakout session here at The Center for Due Diligence's 2014 Advisor Conference. "It's about removing obstacles."

In short, ditch the stick and carrot and just make sure the road is clear. Because, as Smith said, "Behavioral finance is all about making things easier."

The endgame of Smith's research — and subsequent presentation — rests on what she calls her 90-10-90 goals, which dictate:

• 90 percent of employees should be saving, which she admits is conservative;
• At a minimum, they should be saving 10 percent; and, finally,
• 90 percent of those savers should let professionals construct their portfolios.

But Smith's solution is deceptively simple. Manipulate the choice architecture so that "failure works in the employee's favor."

That's where auto-enrollment, auto-escalation and auto-investments take over. Make enrollment the default option, ramp up the savings rate strategically and rely on target-date funds.

But, as Smith says, "The devil is in the details. Or, when you're talking about retirement plans, the devil is in the default. And not every auto-enroll 401(k) is a good 401(k)."

The initial savings rate must be significant but not overbearing, while the auto-escalation should be tied to salary increase, if not January, as well. Smith also suggested target-date funds as a baseline for plan sponsors since 90 percent of participants are what she calls, "delegators," investors who just want to hand the portfolio over to someone else to manage.

Smith then presented a case study that featured a major "retail shopping and entertainment complex" that employs 1,000, half of whom are part-time. This company had no auto-enrollment or default fund.

Starting slow, the new broker sold them on auto-enrolling both new and existing employees at rate of 5 percent in target-date funds.

The staggering, if not altogether surprising, result? In a year, participation more than tripled, jumping from 27 percent to 81 percent. The deferral rate more than doubled, leaping to 5.12 percent from 2.02 percent. And nearly 80 percent of participants invested in the default fund, up from 54 percent.

Finally, co-presenter Svetlana Gherzi, a behavioral finance economist, presented the European organ donor example, a classic case of "opt in" vs. "opt out." Germany asked citizens to check a box if they wanted to donate their organs in case of death. Austria asked its residents to check a similar box if they wanted to refuse organ donation. The result was as predictable as it was dramatic. A paltry 12 percent of Germans chose to donate, while a whopping 99 percent of Austrians made the same choice.

People, whether they're plan sponsors or organ donors, want to take the path of least resistance. They don't want forms, pitches or presentations. They just want the easiest choice.