Seattle ? A researcher believes he can predict the outcome of most any marriage with a few squiggles on a chart.

John M. Gottman said a 20-year study involving more than 600 married couples showed that by carefully plotting how a husband and wife interact and then reducing those observations to a formula, researchers can tell which marriages will succeed and which are heading for the rocks.

In a report at the national meeting of the American Association for the Advancement of Science, Gottman said studies by his Relationship Research Institute and the University of Washington showed that how couples resolved differences was a key factor in whether a marriage would last.

The methods used by couples for conflict resolution can be expressed mathematically or on a simple graphic to predict how the marriage will endure. In effect, math has now found a place in love and marriage, he said.

To gather the data, a team of researchers observed video tapes of couples in interviews by marriage counselors and noted how husbands and wives responded to each other.

Gottman said his team found that there were basically three types of stable marriages.

The first is a husband and wife who routinely avoid conflict.

When a difference of opinion arises, Gottman said, “they will never argue. They will listen to the other, but will not try to persuade.”

Such marriages, which he calls the “avoiders,” may be unemotional and distant, but they endure.

A second type is a volatile relationship “like two lawyers in a courtroom,” Gottman said.

“They can argue at the drop of a hat. They are the Bickersons,” he said. Such marriages tend to last even though there are frequent and impassioned arguments.

The third type of stable marriage Gottman calls the “validating” couple. They listen to each other, respect the other’s opinion and only occasionally argue.

“They pick the issues they fight about,” he said.

Trouble in marriages comes when the couples are a mix of personalities that do not mesh in resolving conflicts. For instance, a husband who is a volatile arguer married to a wife who is an “avoider,” or one who flees from disagreement, may be in marital trouble, he said.

“Couples like that are usually heading for a divorce,” he said.

Researchers mathematically chart the marriage interactions by plotting not just what is said, but also how it is said and the body language and facial expression behind it. Emotions such as anger, harshness and hostility get a negative number, while humor and an eagerness to talk lovingly about the partner get a positive rating.

When these data points are given values and plotted on a chart, it produces a line that dips below a neutral point into negative territory, or a line that soars above the neutral point.

Gottman said follow-up studies had shown the system worked. He said an “escalating negative affect,” or a steep descent on the chart below the neutral point, predicted a couple would divorce within 5.6 years of marriage.

A more gentle descending slope below the neutral point, suggesting an “emotional disengagement,” predicts a divorce within 16.2 years after marriage, he said.

Charts with lines rising above the neutral point plot marriages that last.

By using the charts, Gottman said, it is possible to help stabilize some marriages. For instance, there’s little hope for a marriage where the wife is an avoider of argument and the husband thrives on heated discussion. If she can be taught to respond to his verbal attack while he can learn to tone down his volatility, then they might find a happy middle ground of marriage.

Gottman said that in marriages where this counseling had been applied, about 65 percent of couples remained together for at least one year. This research, however, is still in an early stage, he said.