Dismal market returns haven't exactly created a tailwind for 401(k) and IRA portfolios over the last decade or so, but an equally pernicious -- and more entrenched -- problem is that our brains are messing with our retirement plans.

"We are wired for financial defeat," says Rapid City, South Dakota, certified financial planner Rick Kahler. "Whatever has the most emotional juice right now is what gets our attention. Invest $5,000 in your IRA for a retirement that is 10, 20, 30 years away? Or spend the $5,000 for a vacation to the Bahamas?" All too often, the Bahamas wins out.

William Meyer, founder of Social Security Solutions, notes that our thirst for immediate gratification can easily take a six-figure toll.More than two-thirds of folks opt to claim a lower Social Security benefit starting as early as age 62. For a married couple, than can mean leaving as much as $100,000 on the table. "If you wait to claim until age 70, you're locking in a benefit that is 76 percent larger," says Meyer.

More productive planning

Forever tweaking your asset allocation probably won't get you near the retirement payoff that tweaking your brain will achieve. Consider these strategies for engaging your brain in more productive retirement planning:

Get Thee to a Calculator, Pronto: OK, you know you probably should be saving more for retirement. And when life keeps intervening -- that Bahamas vacation you and yours really really need, or the realization that the kid's orthodontia isn't covered by insurance -- you tell yourself that next year, you'll ramp up your savings rate. You've got plenty of time, right?

What you may not realize is how expensive that time is. Research conducted by Craig McKenzie, a psychology professor at the University of California, San Diego, shows that we have a tendency to "massively underestimate the cost of waiting to save. It's difficult to appreciate the difference between giving yourself 20 years to save and 40 years."

For example, a 30-year-old who is saving $10,000 a year and earning an annualized 6 percent will have $1.2 million at age 65. Care to guess what someone starting at 45 will have? About $390,000. The younger saver invests $150,000 more than the 45-year-old does, and in return has an ending balance that's $800,000 larger. Even if you're already past your 20s and 30s, you might find it eye-opening to see how extending your investment timeline by delaying retirement on the back end of the calculation can help matters. Your company retirement plan probably has an online calculator you can play with; or try this one.

Make it Personal: How you frame retirement savings decisions can help boost your ability to delay gratification. When individuals were asked if they'd prefer to have $3,400 in one month or $3,800 in two months, 57 percent chose the latter. When the same scenario was framed in terms of one's personal age -- "when you are 2 months older" -- 83 percent chose to wait for the bigger payoff.

How does that translate to better retirement planning? Yale School of Management marketing professor Shane Frederick, one of the study's authors, says a 50-year-old who frames a savings goal as "when I am 65" will likely be more patient to focus on that delayed gratification, than someone who frames it as a more generic "in 15 years."

More:
Retirement Planning 2.0: Retrain Your Brain for Financial Success