Thursday, February 15, 2007

The Human Experience of Time

By: Lynn Nadel , Ph.D.

How our brains and minds handle time.

Time, like space, is a central feature of existence.  We live in it, use it wisely or not, and ultimately run out of it.  For all that, few books for a broad audience have tried to combine what we know about the sociology, psychology, and neurobiology of time.  Sarah Norgate attempts to fill this gap in Beyond 9 to 5: Your Life in Time, but the book only partially succeeds, perhaps because time itself slips through one’s fingers when one tries to get a good grip on it. 

Questions About Time

Norgate poses a multitude of questions about time, chapter by chapter, with some being answered rather more usefully than others.  For example, the first chapter essentially asks how different cultures use time and provides a broad picture of the quite different ways in which we value and use time around the globe.  While I don’t understand why the author chose to put this chapter first, it nonetheless provides some fascinating facts.  Did you know that people in the United States vastly underestimate how much free time they have and also feel exceedingly pressed for time?  Or that people in Europe work the fewest hours, have the most holiday time, and have seen their leisure time increase dramatically in recent years?  One might have thought Europeans would feel less pressured by time than Americans do, but, curiously, that is not the case.

How adults use their time throughout the day is the subject of the next chapter, while a separate chapter later on is devoted to babies.  As the author points out, all living things organize their activity in some relation to the daily cycle of light and dark.  Biological systems abound that reflect this cycle, including, of course, our sleep-wake patterns.  Why we sleep, and why we sleep at night, remain hot topics for research, and real-life experiments are under way to test the consequences of changing how we allocate our time between sleeping and waking.  More and more people are working and playing at times for which our biology is not prepared, and only (future) time will tell whether this innovation is good or bad.  Since it is often inadvisable to act counter to our biology, eating junk food in the wee small hours of the morning might be a bad idea.  If that popular activity is a killer, one might expect the proper allocation of time and other healthy habits to lead to an obvious outcome—having more time by living longer.  But of course there is more to it than that, since genetics also plays a central role in determining longevity, as the author discusses in the third chapter. 

The psychology of time—how we experience it—is the part of the story I would have put first.  This, after all, is what Memory is the cognitive function whose purpose is most explicitly aimed at dealing with the passage of time. motivates our interest in all the rest.  Unfortunately, the chapter dealing with this issue is one of the less successful ones in the book, presenting a hodgepodge of observations that do not ever get at the deeper question of how we understand time.  How, for example, do we locate an event in the past, and why are we so poor at pinpointing exactly when something happened?  What does the way we use language in talking about time tell us about how we conceptualize time?  These are but two questions about the general psychology of time that get either short shrift or no attention at all.  Instead, the book provides information about anomalies, such as déjà vu and serving life imprisonment.  Though interesting, the treatment of these minor issues does not substitute for the discussion of normal time cognition that would have enriched the book. 

The brief discussion about infantile amnesia—that time in our youngest lives that we cannot remember—misses an important fact about the brain.  While it is true, as the author points out, that considerable postnatal development of the frontal cortex takes place, no mention is made of the well-documented postnatal development of the hippocampus.  This brain system, agreed by all neuroscientists to be central to exactly the kinds of memories missing in infantile amnesia, is now thought to become functional only after 18 to 24 months of life, which closely matches the period of absolute infantile amnesia.

This would have been an excellent point in the book at which to say something coherent about time and memory.  Norgate does not ignore this topic, but aspects of the relation between time and memory are sprinkled throughout the book, without any synthesis.  This omission surprised me, because memory is the cognitive function whose purpose is most explicitly aimed at dealing with the passage of time. Memory allows us to use experiences from the past to behave more effectively in the present.  What's more, memory also allows us to project ourselves into the future, to plan for times yet to come.  This mental time travel has recently become an exciting area of cognitive neuroscience research.  Scientists have learned that the neural systems engaged in mental time travel, in navigating the past and the future, are largely the same as those engaged in navigating in the present.  A focused discussion of this deep connection between time and memory would have made a useful addition to the book.

Discussion of the physiology and neurology of time and of disorders that affect perception of time comes next, and the two chapters devoted to these topics, though brief, are among the more successful in the book.  The connections between time perception and motor function are particularly interesting, as they further the growing body of research demonstrating intimate links between perception and action in a wide variety of neural and cognitive systems.  One wishes the author had pursued this line a bit more vigorously.  She does explore at some length disorders of timing and how they influence our ability to act effectively in the world.  Here, discussions of such conditions as Parkinson’s disease, autism, attention deficit disorder, and addiction show how problems within systems responsible for time and timing can have very broad consequences indeed. 

An Incomplete Synthesis

Beyond 9 to 5 closes with a chapter devoted to trying to pull the pieces of the earlier narratives together, with mixed success.  It is good to point out that we exist in various scales of time simultaneously.  We live in the moment, make plans about next week, remember what happened last year, study the history of ancient Rome, and ponder the Big Bang billions of years ago.  Pointing out the number and variety of these scales might have been a good place to start.  Here again, one learns many fascinating things, such as how the Aymara (an Amerindian tribe living in the Andes) have a reversed sense of time: they think of the past as in front of them and the future as behind.  In most other cultures it works the other way—the past is behind and the future lies ahead.  But when you consider that the past is knowable and the future is not, the Aymara way seems less strange. This is but one example of how a connection between time, memory, and even language use is stranded without connection to the broader synthesis I hinted at above.

One also learns in this concluding chapter that people in the United States spend more than $11 billion annually feeding their pets, money that could come close to providing basic health and nutrition for most of the world.  Yet people in the United States (and other Western democracies), where food is generally available to all, suffer very high rates of obesity and a host of other life- and time-threatening conditions.  Norgate sees this disjunct between a culture of plenty, which feeds its pets and feeds itself to the point of widespread disease, and a world in which many people are undernourished as exemplifying how “in affluent societies people’s lifestyles are heavily invested in a present time perspective.”  This is an interesting and important connection, all the more so as we struggle worldwide to find lifestyles that are sustainable both for the planet and for the people and animals that live on it.  But this information is buried at the end of a paragraph on page 139. 

Much of the last chapter is devoted to the social conditions that lead to inequalities in how long different people get to be alive and in what they are able to do with the time they have.  One can only agree with much that Norgate writes here. Certainly the world would be a far better place if children did not have to spend their time as soldiers or slave laborers and if women and men were to spend an equal amount of time on child rearing and housework. How to budget our time better and how to use modern technology to improve the time we have, rather than making it ever more frantic, are also suitable topics for discussion.  But in a book that is part of a series called “Maps of the Mind” such issues seem a bit out of place. 

While it may not be fair for a reviewer to bemoan the book that didn’t get written, as well as review the one that did, I feel it appropriate to tell Cerebrum readers that Beyond 9 to 5 will not likely sate their appetite for knowledge about how the mind and the brain handle time.



About Cerebrum

Bill Glovin, editor
Carolyn Asbury, Ph.D., consultant

Scientific Advisory Board
Joseph T. Coyle, M.D., Harvard Medical School
Kay Redfield Jamison, Ph.D., The Johns Hopkins University School of Medicine
Pierre J. Magistretti, M.D., Ph.D., University of Lausanne Medical School and Hospital
Robert Malenka, M.D., Ph.D., Stanford University School of Medicine
Bruce S. McEwen, Ph.D., The Rockefeller University
Donald Price, M.D., The Johns Hopkins University School of Medicine

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