Is it possible that you're aging physically because you believe that you're supposed to? Ellen Langer, a professor of psychology at Harvard University, has written a new book, Counterclockwise, that implores readers to unify mind and body for optimum health.

Q: What does counterclockwise mean? Are you suggesting that we can turn back a physical clock or that we can heal ourselves using only the mind?

A: Yes, I'm telling you both of those things.

Q: So how would that work?

A: We have to recognize that the mind and body are just categories that were given to us by philosophers. There's ample evidence about the mind's influence on the body - not the least of which is the overwhelming effectiveness of placebos. Imagine that you're walking down the street and all of the sudden a leaf blows in front of you. You get startled and your pulse increases because you didn't know what it was. You have a physical reaction to a thought. Or if I see someone vomiting - not a pleasant sight - I start to feel like I'm about to vomit. There's nothing wrong with me, it's again just the idea. So I've devoted my career to finding ways to return this control that we obviously have over our bodies through our minds, and to make that control more direct.

Q: What do placebos tell us?

A: The situation with placebos is that someone lies to you and tells you that this pill that's inert is actually medicine, so when you get better it's clearly not the pill because it's inert. It means that you've made yourself better. So why do we have to go through this whole charade? If we're healing ourselves anyway, there should be a way to harness this and heal ourselves more directly. As I understand it, it's believed that a third of the people with pretty much any disease can self-heal. So why not the rest?

Q: Why do so many people underestimate the role of the mind in physical health and healing?

A: I don't know. My best guess is that, first of all, the body is real and you can see it; you can't see my thoughts. The medical world has helped foster this. You're told that they can't find what's wrong with you and tell you that it's ONLY psychosomatic - as if because it's in your head it hurts less.

Q: How do the mental limits we impose on ourselves keep us from attaining optimum health?

A: When you know something with certainty, then you don't have any reason to continue examining it. Chronic illness, for example, is taken to be something over which we have no control, but you can never show that we can't have control over chronic illness - just that so far there's no way to control it. There's a vast difference psychologically between uncontrollable and indeterminate. If you had something that was uncontrollable, you wouldn't waste your time trying to control it. If you had something that could be controlled, but we don't know, you would go forward and try it. Once we realize that things are always changing, then there's no shame in not knowing. We get a chance to exploit the power in the uncertainty.

Q: Can you tell me a little about the evidence that's led you to some of these conclusions?

A: The earliest study was probably the one where I gave old people plants and encouraged them to make decisions [about where to put it, when to water it and related choices]. The effects were astounding: not only were they happier and healthier and more active, but they lived longer. From the start, I thought there was great potential for us to harness our own well-being.

Q: So when the assumption was made that these elderly people could handle responsibility, they became capable of handling responsibility?

A: Right. What happens is that we have these stereotypes about falling apart. I'm 62 and if I forget something, and if I've bought into these stereotypes, then I start to feel incompetent and it builds on itself. But when I was 40 I forgot things, and when I was 20 I forgot things. The stereotypes become self-fulfilling prophecies, and when it's related to our health that's extremely dangerous.

Q: Can you tell me about the 1959 experiment?

A: What we did there was take a bunch of elderly gentlemen to an environment that was retrofitted so they could live for the week like it was 1959. All the conversations they would be having - like if they were talking about a TV show from way back then - would be in the present tense. We had a comparison group at the same retreat, but their job was to reminisce for the week. They would be speaking in the past, so their minds would always be aware that then was then and now is now. They also showed improvements, but not as much as the other group. We tend to infantilize older adults, and while they were at this retreat they were treated like competent people. We saw improvements in cognitive functioning, like memory and intelligence, and a diminishment of things like arthritis. We took before and after photographs and then had them evaluated by people who had no idea about the study, and in the after photos [the study participants] were seen as looking younger.

Q: So what can we do to break our patterns of thinking?

A: There are a lot of suggestions in the book. The first idea is that when you recognize that nobody knows [anything for sure regarding health], there's reason to stay tuned in and start tending to the variability.

If you have some kind of pain, pay attention to when there's more and when there's less, to the days you have it and the days you don't. Symptoms always change - whether it's asthma, diabetes or cancer - and assuming that it's always going to be the same, we don't look. Ask why you need the inhaler now when you didn't yesterday? When we test out our hypotheses, even if we're wrong the endeavour to test them out turns out to be good for our health.

Prior to the work I described in Counterclockwise is 30 years of work where we made people more mindful and we find improvements to their health and longevity. Even if you don't figure out exactly why you need the inhaler when you do, the search will keep your mind active and that will be good for your health.

Another idea is to recognize that words have a very big impact on us, and we should start paying more attention to differences in words. There's no such thing as "uncontrollable," for example. And look at things like "remission" versus "cure." There's always a distance from where you are to where you want to get to that you can go. If you can't move that foot six inches, try three inches. The fact of going from hopeless and helpless to having some way of helping yourself is very enlivening.