A technology old enough to qualify for Social Security remains the king of American media. Despite the explosion of media options — smart phones, tablets, laptops, gaming consoles — the average American still watches more than five hours of TV a day, according to the media research firm Nielsen.

But while we haven’t replaced the boob tube, we’ve supplemented it with other electronic media, notably smart phones and tablets. Electronic multitasking is on the rise, with 40 percent of smart phone and tablet users reporting that they use their mobile device every day while watching TV.

And it’s not just the younger “digital natives.”

In fact, the age group most likely to multitask with a tablet is those age 55 to 64. That could reflect, in part, greater tablet ownership among more affluent seniors.

But for several years now, research has consistently shown that older Americans are pretty much in step with the digital movement. They lag behind in texting, but not really in much else.

Not surprisingly, the continued growth of streaming video has led to a drop in time spent viewing DVDs and a rise in time spent watching video on the Internet, whether on laptops or mobile devices. But daily time on the Internet (outside of work) still adds up to only about an hour and a half for the average American – less than a third of the time he or she spends watching TV.

How does one explain the ongoing appeal of TV?

I’d say there are a number of factors at work. With the growth of cable over the past 25 years, there’s simply more programming available on more channels at any time of the day or night. Most viewers, most of the time, will be able to find something that feeds their need to sit back and zone out for awhile.

The larger screen offers a superior viewing experience. And don’t discount the force of ingrained habit for anyone over the age of 20.

But these discussions will be moot before long.

One day soon, most American households will enjoy a complete melding of media – the long-promised day when the TV becomes the computer, the computer becomes the TV, and all content is available on all devices. Services like Netflix and Hulu already offer a taste of this capability, but it’s far from seamless.

When that shift occurs, Nielsen will have to find new ways to measure the media we’re consuming. And we may find out just how far the limits of human endurance will stretch.