Communications of the ACM
Are Two Monitors Better Than One?
Credit: Eichlervision.com
The idea that workers in a data-intensive environment will work better and faster if equipped with more than one monitor seems to be "settled science," according to the author of two of the issue's landmark studies. Others, though, disagree.
"I'm really satisfied that the theoretical principles are in place," says James Anderson, professor of communications at the University of Utah. "I think I have enough information and have provided others with enough information that they can look at a work process and make some pretty good decisions about what the display configuration ought be."
Anderson conducted studies on the best screen configuration to promote productivity in text and graphics editing and spreadsheet administration in 2003 and 2007, and concluded that using multiple monitors increases productivity for any task that requires multiple windows to be opened simultaneously.
"It really isn't rocket science," he says. "It is simply a question of matching the desktop real estate to the footprint of the work. The single 15- to 17-inch monitor which has been the majority of the U.S. installed base is a—if not the singular—productivity impediment across U.S. business practices. If a global rather than a case-by-case decision has to be made, then nearly every work position will benefit from dual monitors."
Microsoft Web Community architect Scott Hanselman has been a multiple-monitor advocate since the late 1980s, and says he doesn't need a study to convince him of multiple monitors' benefits.
"A Web developer has a very basic work flow," Hanselman says. "Write code, see how it looks in the browser. You don't need a study to tell me that having a browser up on one monitor and the code on another is not radically more efficient. How is that controversial?"
However, the ever-changing landscape of screen sizes and properties make the question of "one screen or two?" increasingly hard to answer. In his 2007 study, Anderson discovered large (24-inch or more) widescreen monitors perform better than dual screen configurations when the work fits the monitor. The widescreen monitor showed 18% better performance than a single 20-inch display and 6% better performance than a dual 20-inch display on a text-editing task where the task nicely fits the available desktop space. The 24-inch monitor lost that advantage in the spreadsheet task, with a slightly larger (26-inch) widescreen declining even more.
"There isn't going to be a magic bullet and an article isn't going to write itself, but if I can save you 20 minutes a day from the time you spend resizing a window, then at the end of the week I've given you almost two hours," says Anderson. "That's a small gift."
'I Need Time to Think'
Some workers believe the multiple monitor theory is highly overrated, however, and Anderson himself recounts an instance of it.
"I have a friend who bragged about how well he did on a 15-inch monitor, and I was able to demonstrate to him that he would save a substantial amount of time if we went to multiple monitors," Anderson says. "He said, 'I don't want to work in multiple monitors. I don't care that I save time. I need time to think and consider what it is that I'm writing, and a single monitor serves me well.'"
University of Michigan psychology professor David Meyer harbors deep doubt about the pervasive benefit of multiple monitors.
"Unless you're using the monitors to perform a single integrated task of some kind, then the temptation to be switching between independent tasks is going to get you into inefficiencies as well," Meyer says. For example, a copy editor at a busy news desk may lose focus on an editing task if he or she is also expected to simultaneously evaluate reporters' incoming Twitter feeds.
"Irrelevant input is really, really bad, but even if it is relevant, if you're switching back and forth between distinct tasks, which is an option enabled by multiple monitors as well, that isn't good either."
Clay Johnson, co-founder of Blue State Digital, the firm that built and managed Barack Obama’s online campaign for the U.S. presidency in 2008, has also experimented with numerous monitor setups and concluded that the number of monitors isn't the key factor in more efficient work. For Johnson, the improvements hinge on the number of pixels in sight and, as Meyer contends, the elimination of distractions.
"Even having relatively static things up in extra screen space is a distraction," Johnson wrote in a post about pixels and multiple monitors on his blog, Information Diet. "A to-do list in a second monitor is nothing but a constant reminder of other things you could be working on other than the task at hand. Keeping anything up other than what you’re working on is a great way to keep yourself distracted from doing the important stuff you don’t want to do."
"You don't want to confuse multiple monitors with the illusion of multi-tasking," Hanselman says. "Multi-tasking is a lie, but having to alt-tab between windows takes up just a tiny bit of energy every time you do it. It's not about multi-tasking. It's about glanceability. I can turn my head faster than you can alt-tab."
Both Meyer and Johnson say the fact Anderson's studies were funded by monitor manufacturer NEC should give readers pause about his findings. Anderson, however, says his work, like all other research at the university, must undergo scrutiny by an institutional review board. "You'll never work again if somebody discovers you’re cooking data," Anderson says.
In fact, Anderson decries the industry's widespread practice of promoting screens with a 16:10 aspect ratio instead of a 4:3 ratio, which more closely mimics the 8.5 x 11-inch dimensions of a sheet of office paper, because they can get more monitors out of a single sheet of glass.
"I'm surprised business hasn't said, 'We don't care, this 4:3 is the monitor that works best for the job we have to do and you need to produce these monitors in a way that's cost effective,'" he says. "I think many managers just don't think about these types of things in terms of the work process."
One finding in Anderson's 2003 and 2007 studies—that workers who are novices at a particular task reported higher productivity gains with dual monitors than experienced workers—might be a valuable insight in a climate in which many part-time, adjunct, and temporary workers are more frequently filling roles that used to be assumed by full-time employees.
"I don't know where else you get a bang for the buck like that," he says. "If the only thing you can do is have one configuration for everybody in your office, make it a dual monitor configuration. Over the long run, it will work fine for most of your people. People who don't like multiple monitors can turn the extra one off."
Gregory Goth is an Oakville, CT-based writer who specializes in science and technology.
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