We buy stocks, planning to stick with them for the long haul. But when the market is plunged into turmoil, as it was last week, our conviction wavers and we start second-guessing our investment plan.

How do we keep ourselves on track?

Here are some strategies:

Cover Your Ears
Thanks to the abundant information available through the Internet, on television and in newspapers, investors are better informed. But we are also more jumpy.

"If you watch CNBC, you'll hear an investment idea that sounds good every 10 minutes," says New York investment adviser Milton Stern. "But if you act on those ideas, the likelihood that you'll do well is very low. You have to keep in mind how difficult it is to beat the market."

Not only do we frequently hear new investment ideas, but also we are constantly reminded of how our current holdings are faring.

"There's a real mismatch between the length of our investment horizon and how often we get feedback on our strategies," says Nicholas Barberis, a finance professor at the University of Chicago. "A lot of us are long-term investors and yet we get all this short-term information. If you get out at the first sign of trouble, you're not going to get those long-run returns."

What to do? "Keep your total financial wealth in mind," Mr. Barberis suggests. "Part of the problem is that many people focus on gains and losses in individual investments. That only makes things worse, because you're bound to have a loss somewhere."

Know What You Own
We are more likely to abandon investments we don't fully understand. That may explain why so many investors have little in foreign stocks and why they are often quick to dump technology companies, with their sometimes-incomprehensible products.

We are also more likely to get rattled if we have unrealistically high expectations. Historically, stocks have returned some 11% a year before costs. But thanks to the extraordinary gains of the late 1990s, many folks now expect far fatter returns and are no doubt queasy about this year's lackluster market.

"People have become way too used to 20% returns," says Michael Maloon, an investment adviser in San Ramon, Calif. "Our big job right now is managing expectations. We're showing people that they've done great over the long haul. But part of the long haul is these bumps in the road."

Know Yourself
Stocks will do what they want. The question is, how will we react?

"People need to separate their psychological needs from their financial needs," says Hersh Shefrin, a finance professor at Santa Clara University and author of "Beyond Greed and Fear." "Their psychological needs are short term and their financial needs are long term."

Unfortunately, many of us find it hard to simply buy and hold. When we hear about the successes of others, we are tempted to change strategy. When stocks plunge, we assume they will keep on falling. When our investments perform well, it bolsters our self-confidence and encourages us to trade even more.

"Knowing yourself is really important," Mr. Shefrin says. "If you don't have a long-term plan in place, if you don't know yourself and if you don't understand what you own, you are very likely to act when those emotions kick in."

Write Your Own Rule Book
We may consider ourselves long-term investors. But every day, the stock market gives us the option of changing our minds. That is bad news for nervous investors, because it is all too easy for them to bail out of stocks.

To fend off that temptation and stay on track, folks should write down their investment strategy, suggests David Bugen, a financial planner in Chatham, N.J.

"Every day, we're bombarded with new information," he notes. "If you commit your long-term investment strategy to writing, it helps to alleviate the normal human tendency to overweight new information that may contradict previous assumptions."

What should this written strategy include? Spell out your target mix of stocks, bonds and cash investments. Describe how you will diversify your stock portfolio. Specify how much you will save each month and what goals you are saving for. List why you bought each investment -- and why you might sell.

Many folks, of course, will deviate from their written plan. But thanks to the plan, they probably won't deviate too far.

Never Say Never
If we settle on a 60% stock allocation, we should try our hardest to stick with it. But that doesn't mean we should hang on to any particular stock or stock fund. The fact is, the broad market may climb over time. But many stocks and funds won't go along for a ride.

"People tell themselves they'll sell their losers," Mr. Barberis says. "But when it happens, they hold on, because they can't bring themselves to take the loss. For psychological reasons, people sell their winners too soon and hold their losers too long."