by SARAH MUSGRAVE

Couples used to have chemistry. Now they have math. A study called The Mathematics of Marriage uses differential equations to predict with 90 per cent accuracy whether newlyweds will split up within five years. The 2003 findings, resulting from an unusual collaboration between University of Washington mathematician Jim Murray and psychologist John Gottman, continue to make waves in the scientific community. B.C. professor Rebecca Tyson, a former researcher on the project, will lecture in Montreal just in time for Valentine's Day.

Mirror: The study is called the Mathematics of Marriage, but do the findings apply to relationships, too?

Rebecca Tyson: Absolutely. They're based on experiments which can only study a part of the marriage, you can't study the whole thing. They're about discerning stable relationships from unstable relationships. And the model is a model of the relationship in a particular circumstance, which is related to these experiments. The experiments we worked with were based on how a couple resolved conflict. So they would have a discussion, and the model is a model of this discussion process.

M: What kind of problems did they discuss?

RT: The big ones are money, kids and... sex, I guess, is the third one. Something that ran deep.

M: So like, "You clip your toenails in the living room while I watch TV"?

RT: Well, before the experiment a lot of work went into identifying an area of real conflict. When they show up for the experiment they already know what they're supposed to talk about. They're left on their own to talk about it for 15 minutes, there's no interfering in the discussion, and it's taped.

M: I know you looked for responses ranging from humour to contempt. How did you rate what you saw in the love lab?

RT: The psychologists have well-defined scoring methods. There are coding systems, and from the coding systems you get scores... For example, the phrase "yes, but" is given a code, so are positive facial responses, negative facial responses... A couple that's stable will have a lot of positives, so if you plot that number against time, you'll find the graph goes up and up and up. It might go down for a while but in general the trend is up. An unstable couple will have a graph that goes down.

Validators, volatiles and conflict avoiders

M: We all know couples who seem to hate each other but stay together...

RT: There are some very unhealthy relationships that stay together. It turns out there are three kinds of stable marriage. One of them is the modern therapy model, the validator, as John [Gottman] dubbed it. They talk to each other in very respectful language, they listen to each other and they negotiate in a way that we all recognize. But there are two others. One is called the volatile, which is what we think of when we think of a Mediterranean temperament: you fight really hard but you love really hard, too. Those are also stable marriages, there's a lot of passion in them. And then there's the conflict avoider marriages, where it's just too punishing for them to disagree on anything so they just tiptoe around the subjects. They basically don't go there, they agree to disagree. And they can last just fine. So in terms of people who can't stand each other, I don't know, but they might fall in the volatile category.

M: They argue a lot but then they have great sex.

RT: Exactly. Those are fine!

M: Can math help save marriages?

RT: Everybody would like to know before they get married, right? And apparently, couples before they get married behave quite differently than couples afterwards. So this formula, this test, to see whether or not you're compatible has been elusive so far. What the mathematics can do is pinpoint precise mechanisms in the relationship. It's more quantitative than the previous psychology all by itself, so it then gives the psychologists or the therapists something very specific to target in trying to help the couple deal with things.

M: What's been the public reaction?

RT: People tend to be very math-phobic. The public reaction is a mix of incredulity and fascination. People are interested, thinking maybe there is a simple answer, maybe there is a formula. But at the same time people can't stand the idea that a formula could quantify something as personal and individual as a marital relationship. So it's quite a mix, which is probably healthy.

M: Are you married?

RT: Oh, yes.

M: And did you test yourselves?

RT: Oh, no. The problem is I know how the whole thing works.

Rebecca Tyson speaks at the Redpath Museum (859 Sherbrooke W.) on Thursday, Feb. 10, 6 p.m.