Economists often seem to take a perverse satisfaction in publishing papers showing that people don't always behave rationally. We don't save enough in our 401(k)s. We're not always shrewd about planning for the future. We can be unduly swayed by nice weather when buying a car or a house. And now it turns out we pitiable humans can't even watch television in an economically efficient fashion.

I don't even know what I'm doing anymore. (AP)

That's right. Television. An amusing new paper (pdf) by Constanca Esteves-Sorenson and Fabrizio Perretti shows how people are fairly irrational when it comes to channel surfing. All too often, the researchers found, people tend to stick with whatever channel they're currently watching, even if the show is boring, or even if there is something more appealing on another channel.

That seems plausible enough. But how did the economists actually figure this out? By studying the viewing habits of Italian television watchers between 1990 and 2003. Because Italian TV is largely dominated by two companies (one of which is owned by former prime minister Silvio Berlusconi), that means that just six channels accounted for a whopping 90 percent of television-watching over this period. That made the data manageable. What's more, Italy happens to have an extremely thorough system for tracking what people are watching minute by minute.

What the researchers found, sifting through the data, is that inertia tends to prevail in viewing habits. Even though Italian couch potatoes had plenty of information about what other shows were on, they usually just stuck with whatever was next on their current channel. For instance: "When a female show, such as a romantic series, precedes the news, more women watch the news than men. By contrast, when a male show, such as soccer, precedes the news, more men watch the news than women." This was true even when there was a show on another channel that usually attracted these audience.

The authors tried controlling for all sorts of factors—from drizzly weather (which increases the number of TV viewers) to the possibility that people might tune in early to a previous program so as not to miss their favorite show up next. But the results held up. Once people finish a show, they're far more likely to stick around for whatever's next, even if there's something that should be more appealing on another channel. "A show's audience," the authors conclude, "increases by 2-4 percent with an increase of 10 percent in the demand for the preceding programme."

Television executives, meanwhile, are almost certainly aware of this principle. The economists quote Steve Sternberg, an advertising executive, who once said that "you could read the phone book after Seinfeld and get a 25 percent viewer share." It's a funny line, but it's also a huge business opportunity. And the TV behemoths in Italy understand the principle. The authors argue that Italian TV programming is almost certainly set up to take advantage of this viewer inertia — if it wasn't, the audience would likely be about 2 percent smaller and profits for the TV companies would plunge 20 to 40 percent.

So why do people linger on a channel even if they're bored? Past studies of inertia in American boob-tube habits have suggested that maybe there are just two many options, so viewers are paralyzed by choice. Or perhaps viewers don't have accurate information about what else is on. But neither of those things were true in Italy during the 1990s, where there were mainly just six channels. Most likely, inertia stems from good old-fashioned procrastination. That sounds obvious enough. But now there are equations and everything to back it up.

(For the link to the paper, many thanks to R.S.S. of Free Exchange, who has a good discussion of the research and an amusing anecdote about Rupert Murdoch, who used to complain that the BBC would take advantage of viewer inertia to trick people into watching cultural programs.)