Subsequently, Robert D. McIlwraith of the University of Manitoba extensively studied those who called themselves TV addicts on surveys. On a measure called the Short Imaginal Processes Inventory (SIPI), he found that the self-described addicts are more easily bored and distracted and have poorer attentional control than the nonaddicts. The addicts said they used TV to distract themselves from unpleasant thoughts and to fill time. Other studies over the years have shown that heavy viewers are less likely to participate in community activities and sports and are more likely to be obese than moderate viewers or nonviewers.

The question that naturally arises is: In which direction does the correlation go? Do people turn to TV because of boredom and loneliness, or does TV viewing make people more susceptible to boredom and loneliness? We and most other researchers argue that the former is generally the case, but it is not a simple case of either/or. Jerome L. and Dorothy Singer of Yale University, among others, have suggested that more viewing may contribute to a shorter attention span, diminished self-restraint and less patience with the normal delays of daily life. More than 25 years ago psychologist Tannis M. MacBeth Williams of the University of British Columbia studied a mountain community that had no television until cable finally arrived. Over time, both adults and children in the town became less creative in problem solving, less able to persevere at tasks, and less tolerant of unstructured time.

To some researchers, the most convincing parallel between TV and addictive drugs is that people experience withdrawal symptoms when they cut back on viewing. Nearly 40 years ago Gary A. Steiner of the University of Chicago collected fascinating individual accounts of families whose set had broken--this back in the days when households generally had only one set: "The family walked around like a chicken without a head." "It was terrible. We did nothing--my husband and I talked." "Screamed constantly. Children bothered me, and my nerves were on edge. Tried to interest them in games, but impossible. TV is part of them."

In experiments, families have volunteered or been paid to stop viewing, typically for a week or a month. Many could not complete the period of abstinence. Some fought, verbally and physically. Anecdotal reports from some families that have tried the annual "TV turn-off" week in the U.S. tell a similar story.

If a family has been spending the lion's share of its free time watching television, reconfiguring itself around a new set of activities is no easy task. Of course, that does not mean it cannot be done or that all families implode when deprived of their set. In a review of these cold-turkey studies, Charles Winick of the City University of New York concluded: "The first three or four days for most persons were the worst, even in many homes where viewing was minimal and where there were other ongoing activities. In over half of all the households, during these first few days of loss, the regular routines were disrupted, family members had difficulties in dealing with the newly available time, anxiety and aggressions were expressed.... People living alone tended to be bored and irritated.... By the second week, a move toward adaptation to the situation was common." Unfortunately, researchers have yet to flesh out these anecdotes; no one has systematically gathered statistics on the prevalence of these withdrawal symptoms.

Even though TV does seem to meet the criteria for substance dependence, not all researchers would go so far as to call TV addictive. McIlwraith said in 1998 that "displacement of other activities by television may be socially significant but still fall short of the clinical requirement of significant impairment." He argued that a new category of "TV addiction" may not be necessary if heavy viewing stems from conditions such as depression and social phobia. Nevertheless, whether or not we formally diagnose someone as TV-dependent, millions of people sense that they cannot readily control the amount of television they watch.

Slave to the Computer Screen

Although much less research has been done on video games and computer use, the same principles often apply. The games offer escape and distraction; players quickly learn that they feel better when playing; and so a kind of reinforcement loop develops. The obvious difference from television, however, is the interactivity. Many video and computer games minutely increase in difficulty along with the increasing ability of the player. One can search for months to find another tennis or chess player of comparable ability, but programmed games can immediately provide a near-perfect match of challenge to skill. They offer the psychic pleasure--what one of us (Csikszentmihalyi) has called "flow"--that accompanies increased mastery of most any human endeavor. On the other hand, prolonged activation of the orienting response can wear players out. Kids report feeling tired, dizzy and nauseated after long sessions.

In 1997, in the most extreme medium-effects case on record, 700 Japanese children were rushed to the hospital, many suffering from "optically stimulated epileptic seizures" caused by viewing bright flashing lights in a Pokémon video game broadcast on Japanese TV. Seizures and other untoward effects of video games are significant enough that software companies and platform manufacturers now routinely include warnings in their instruction booklets. Parents have reported to us that rapid movement on the screen has caused motion sickness in their young children after just 15 minutes of play. Many youngsters, lacking self-control and experience (and often supervision), continue to play despite these symptoms.

Lang and Shyam Sundar of Pennsylvania State University have been studying how people respond to Web sites. Sundar has shown people multiple versions of the same Web page, identical except for the number of links. Users reported that more links conferred a greater sense of control and engagement. At some point, however, the number of links reached saturation, and adding more of them simply turned people off. As with video games, the ability of Web sites to hold the user's attention seems to depend less on formal features than on interactivity.

For growing numbers of people, the life they lead online may often seem more important, more immediate and more intense than the life they lead face-to-face. Maintaining control over one's media habits is more of a challenge today than it has ever been. TV sets and computers are everywhere. But the small screen and the Internet need not interfere with the quality of the rest of one's life. In its easy provision of relaxation and escape, television can be beneficial in limited doses. Yet when the habit interferes with the ability to grow, to learn new things, to lead an active life, then it does constitute a kind of dependence and should be taken seriously.