Demand was particularly strong among workers early in the lifecycle. Participants electing target-date funds on their own, rather than being defaulted or mapped into them, were equally likely to be pure target-date versus mixed target-date fund investors. In other words, preferences for the features of target-date funds among those making voluntary decisions were not simply a binary, all-or-nothing choice. Demand for such funds was also quite resilient to equity market conditions, since active adoption of target-date funds increased somewhat during the recent financial crisis.

As expected from prior research, automatic enrollment of new hires did raise target-date adoption: they were 81 percent more likely to elect these funds, compared to an "unguided" outcome. When employers reenrolled participants from a prior default to new target-date default funds, adoption rates also rose by a similar amount, up 71 percent among new entrants. When employers eliminated a fund from the menu and "mapped" participants into target-date funds, target-date adoption rose by 166 percent among new entrants, and more than doubled among existing employees.

The report's authors concluded that "responsibility for portfolio decisions is gradually shifting away from workers to employers through the growth of target-date funds in 401(k) plans. In default arrangements, this effect is direct: account contributions are invested in target-date funds at the explicit direction of the employer. When participants actively choose the funds, this effect is indirect: many participants adopt quite different allocations in response to the introduction of the target-date equity glide paths into the plan menu. Regardless of the decision-making mechanism, many retirement plan investors appear to have malleable or ambiguous preferences for portfolio choice, because of lack of financial knowledge and experience, behavioral biases, or other reasons."

The report concluded that, "Households seem particularly willing to rely on default or simplified advice arrangements when facing complex and consequential financial choices. Inertia, too, is a dominant heuristic, not only in saving behavior but in portfolio allocation decisions. Policy prescriptions in such instances might include not only default arrangements, but also programs or services that offer simplifying choices and/or embedded advice. An important question for future research is whether such design principles can also inform household decisions of consequence in other domains, including the choice of health insurance plans, taxable saving and investments, mortgage instruments, and insurance."