08/13/2012 10:38 am ET Updated Oct 13, 2012

Secrets of the Digital Speed Limit Sign: How to Improve Performance at Work

Have you ever wondered why digital speed limit displays work? I'm talking about the ones that flash your current speed in lights on a sign. If you think about it, they really shouldn't make a difference. They don't do anything to make you slow down, and they don't tell you anything you don't already know. And yet, if you have one on your daily commute like I do, you know how that digital display of speed inspires nearly every driver to tap their brakes, in a way a normal speed limit sign never has.

Why is that digital roadside display so much more powerful than the same information when it's displayed on your dashboard? The answer, it turns out, contains the secrets of getting people to adjust their performance not just on the road, but at work too.

First and foremost, the roadside display presents objective feedback as an interrupt. The information is factual, and it's presented in on a sign that's bright, colorful, dynamic, and a little unusual. And while it's easy to unconsciously tune out the information we see regularly -- speed limit signs being one of them -- it's a lot harder to tune out something that interrupts your normal perceptions with something unexpected. So, the information is more likely to get through your filtration system and reach your awareness.

I've written about automotive interrupts before. If you've ever been in a room with a group of people and a TV in the background -- in a busy hotel lobby, for example -- you already know the power of an interrupt. The news blares from the TV continuously, and is more or less ignored by most hotel employees and patrons as they go about their business. But if a sharp tone emanates from the TV, and the words "we interrupt this broadcast to bring you a special update" are uttered, attention shifts. Most conversations stop, and most eyes turn toward the screen. Interruptions win attention.

Besides being an interrupt, the speed limit display is also a form of instant feedback. That's the second reason for its effectiveness: It shows you exactly how fast you're going in comparison with the standard. Sure, you could garner the same information by reading a conventional speed limit sign, and then checking your own speedometer by comparison. But that would require two steps -- reading here and reading there -- plus the cognitive action of comparison. While that's not terribly difficult to do, it's a whole lot easier not to do it. As a result, you just keep driving without making changes. But when the work is done for you -- when you see your speed side by side with the limit -- in a fraction of a second you know how your performance compares with the guideline. Now, you're left to decide what to do with that information.

That's the reason fundraisers like to display a thermometer or other graphic indicating how much money has been raised relative to a preset target. The graphic does the work for you, instantly demonstrating how much more is needed. You're left with only one assignment: to decide how to act upon the fact that there's a gap.

Speaking of information, the third reason that the digital speed limit sign is so effective is that it's showing your speed not just to you, but to other drivers as well. If you're speeding, people are going to know it! So, even though it's displaying objective data -- and not judging you in any way -- the roadside sign is telling other people what you're doing, thereby placing social pressure on you to conform.

Extensive psychological research has repeatedly proven that other people influence both our perceptions and our willingness to act. As it turns out, the question of whether you're willing to break with social norms -- to speed, in this case -- most likely has a different answer based upon whether others will know that you're doing it. By the way, the research is pretty convincing that you'll disagree with that last statement -- asserting your autonomy from such pressures -- and that you'll be wrong. When it's apparent that others can see what you're doing -- when your speed is posted on a billboard, side by side with the posted limit it exceeds -- you feel much more pressure to correct the situation than you would if the information were displayed privately in your car.

Finally, the roadside sign system works because the correction is self-policed. I suppose there have been instances of police with radar traps set up adjacent to the digital displays, but in general you don't usually see the two together. The digital displays give you actionable information, but they leave the decisions about what to do with the information to you. Thanks to the social pressure, you're likely to bring yourself into compliance.

There's a good chance that the self-policing increases the effectiveness of the system. When you pass a live radar trap, the control is externally imposed. So you slow down, pass the trap, and speed up again, with the goal of avoiding a ticket. But when you pass the digital sign, you make the decision to slow down on your own -- or at least you think you do, since you're unlikely to recognize the social pressures involved. And since it feels like your decision, you're a lot more committed to it. Think of the difference between how you work for a boss who watches over your shoulder, and one who tells you she's relying on you to check yourself: You're a lot more committed when the responsibility is yours.

How can you apply the principles of the digital speed limit sign to the workplace?

Let's imagine you have an employee who does some sort of routine work, and is falling short of the target production rate. First, find a way for the objective feedback to interrupt the person as she works: Post a checklist on the wall in front of her desk where she is asked to mark off each task as she completes it. Second, make the difference between current and expected performance clear: Design the checklist to contain the target number of items expected for the day, so she can see how far she has progressed by how many items are left unmarked. Third, make it visible to others: have someone come by once a day and comment positively if she is ahead of schedule. Fourth, make the system non-judgmental and self-policing: don't allow that reviewer to comment negatively if she is behind schedule, and don't allow her management to collect her checklist at the end of the day. Allow her to correct herself.

Implement that system, and your employee's output is likely to jump up. And that's not just me speaking hypothetically. The example comes from a performance improvement case study that yielded substantial productivity improvements.

So the next time you pass a digital speed limit display, remember: it's not just a way to get everyone to slow down -- it's a model for changing human performance, subtly and effectively.