The more confusing the market seems to get, the more investors need to develop their voice of reason.

That’s the call of logic they hear in their head that, hopefully, reminds them of their long-term plan even as market forces seem to be ripping it apart right now.

It’s the reminder that they had a reason for building their plan, and that they probably want to ignore the reasons the market is throwing out that would lead to blowing that plan up.

The two current examples are emerging markets and bonds, where investors are being whipsawed by a market that most assuredly is not turning out according to expectations.

Amid market turmoil, just be calm

Entering the year, many advisers were suggesting that investors cut back on bond allocations, not only because they expected interest rates to rise, but because the long-term picture shows that it could be hard to produce attractive returns for the next half-decade or more without accepting significant risks, the kind of concerns most people are trying to avoid when they buy bonds.

On the emerging markets side, many of the same advisers entered the year suggesting that emerging markets were starting to reach the point where they were such attractive values that a little bit of buying was in order. For all of their potential short-run troubles, few experts deny the long-term earning potential of emerging markets, and troubles were bringing prices down to near-bargain levels.

And then the bond market started to look attractive and had a great January, and emerging markets went in the tank.

That’s a potential problem for anyone who took the “avoid bonds, nibble in emerging markets” tack, because they now feel they have missed a rally in one asset class, and bought into trouble in the other. The last thing they want to do right now is stay the course.

“Most people blame the market when they buy something and what they buy doesn’t do well,” said Donald MacGregor of MacGregor-Bates Inc., which researches investor judgment and decision-making. “But when they buy something and it does well, they attribute the success to themselves.

“But if they look more closely, they may see that it’s not that the investment didn’t perform, it’s that they had an unrealistic time frame,” he added. “If you were buying emerging markets for their potential for the next five or 10 years, but now you are selling because of the last month, you need to have a talk with yourself—or with your adviser—and get back to that voice of reason.”

Karl Mills, president of Jurika, Mills and Kiefer in San Francisco, noted on my show this week that balancing long-term thinking against current events can be delicate, but that the big picture should win out. In his first-quarter commentary for 2014, Mills called bond investing “fishing in an empty lake,” and recommended increased exposure to Europe, Japan and emerging markets through “value-oriented strategies.”

Still, he’s not surprised that the market worked against those picks in the short term, and he hasn’t seen anything in the last few months to change his long-term thinking.

“If you think over the next five years and how you want to allocate your money, I wouldn’t want to take $1000 in Treasury bonds and put it in a box in the ground because I think there’s a high chance I would have lost real purchasing power. I think it’s an inevitability that interest rates will go up—as Bogart said, ‘Someday and for the rest of your life—that long-term picture hasn’t changed.”

On emerging markets, Mills also was looking at inevitability, suggesting that the tide in those developing economies will kick in over time.

“You do want to buy things when they’re down,” Mills said. “Things are down when they look scary, and they look scary when they are down. That’s kind of how it works.”

That’s precisely why investors come up with diversification plans and investment policy statements, or why those who don’t find that when they eventually seek out financial guidance that the first step they go through with an adviser is developing a long-term philosophy.

“A well-diversified portfolio is almost always going to own something that is currently out of favor,” explained Dan Dorval of Dorval & Chorne Financial Advisors in Maple Grove, Minn. “The real power of diversification is rebalancing between non-correlated assets to harvest gains from the best performing categories and buying beaten-down investments at more-attractive prices. This disciplined process may underperform over the short term as the dominant trend progresses, but will eventually pay off over a full market cycle that includes several trend reversals.

“Emerging markets will continue to underperform right up until the point when they don’t and that is when diversification combined with disciplined rebalancing will be rewarded,” he added.

Adam Grimes, chief investment officer at Waverly Advisors, noted during a radio interview that investors will feel more of the directional tug in the near future and with the broad domestic stock market, saying he believes the next few weeks—if they are flat or down—could portend a 15 percent decline that could extend to mid-year, but noted that even that decline does not change a positive three- to five-year outlook for stocks.

“The problem comes when somebody says ‘I’m a longer-term investor and then finds themselves making emotional reactions to 5 percent swings in the market,” Grimes said. “If you are doing that, you are not a longer-term investor. If you are a longer-term investor, then you have to act appropriately in that time horizon.”

Added MacGregor: “You either argue this out with yourself or your adviser and forge a strategy that doesn’t get shaken by what happens for a month or a quarter, or you go out and take your knocks because all of your reasons boil down to ‘What can I make a killing on now?’ without realizing that can also be how you let the market kill you instead.”

More from Chuck Jaffe:

The trouble with Obama’s myRA plan

How investors should read the news