I had been in Israel for about a week. I was driving, inundated with the signs on the street around me, the different types of traffic lights, and trying to follow the instructions Waze was giving me. One traffic intervention caught my attention. A speed display flashed “90 km/hr” and then gave me this: ☹. I slammed on my brakes, and was filled with a feeling of guilt. The speed limit was 80 km/hr. Whoops.
I have to be honest here and admit that I have been known to go over the speed limit. But this time, a combination of a circle, two dots, and a curved line made me feel the disapproval. Now, there is good reason to drive at appropriate speeds. In the United States, speeding contributed to 27% of the fatalities in car crashes in 20151. Speeding reduces a driver’s ability to steer safely around curves or objects in the roadway and extends the distance necessary to stop a vehicle2. Because of this, different speed reduction mechanisms exist—law enforcement, speed bumps (very popular, and nausea-inducing, in Israel), speed limit signs, and, as technology has advanced, speed indicator displays.
Speed indicator displays have been used in various countries in order to provide drivers with immediate feedback on their speed. The timing is crucial: the sign must be far enough away that the driver has time to read the display, yet near enough that she knows it is her car the sign is referring to.
First, why might these feedback signs work? After all, if a driver just looks at their own dashboard, don’t they see their own speed? The answer is, of course, yes — but we become desensitized to stimuli that are always in front of us as we habituate to them. Conversely, a new sign catches our attention, and thus can help someone who had no intention of speeding. And for those of us who were perhaps intentionally ignoring our dashboard? A psychologist might surmise that there is some public shame to having your misdeed posted to the world. Your private deed has become public, and as we can all attest to, that changes behavior.
A study in London3 reported that speed indicator displays effectively reduce driving speeds within a short distance of a sign (400 meters). However, there is also evidence suggesting that, after two weeks, drivers become desensitized to the sign and it is no longer that effective. Not surprisingly, drivers are most responsive if the sign is associated with a police car enforcing speed down the road.
And what about adding the emotional cue of a ☹?
Face processing is a particularly special type of processing. Infants develop an early competence in ability to process faces, and prefer looking at faces than other objects from birth4. Early facial perception abilities, together with neuroscientific research implicating certain brain regions in facial processing, provide evidence that we are wired to pay attention to faces5. Why are we wired to respond to faces? As a primate, recognition of individuals at first sight is important. Unlike my dog, I do not have a powerful olfactory system that can “smell” the other person; I rely on sight to recognize my own child, mate, or enemy. We not only recognize people by their faces, but we also read faces for emotion. The expressions on someone’s face tell us whether we need to prepare to fight, flee, or receive a hug. In fact, there is even research that we unconsciously move our muscles somewhat to mimic the expression we see on someone else’s face6, highlighting our social nature.
We process faces and the emotions displayed rapidly (less than 100 milliseconds in some studies), and without conscious awareness, suggesting a certain level of automaticity in facial processing. In other words, we quickly process a face and it doesn’t demand that much of our attention7, both important points for trying to induce behavior change while someone is speeding by at 90 km/hr.
But, wait a second, it’s not a real face on those speed indicator displays; it’s a simple symbol of a face, or an emoji. Does our brain even process an emoji like a real face?
Research suggests that yes, with the increasing use of face emojis, humans have learned to react similarly to emojis as they do regular faces8. Interestingly, however, if you have somehow avoided the digitally social world we are in, you may not react the same way. For cultures that are not exposed to face emojis like ☹ or ☺, the emojis do not have the same effect9.
Research in London showed that after a while speed indicator displays become less effective. And truth be told, after five months of now driving on that same road, and, admittedly, sometimes seeing that sad face, I don’t react as much. I am not startled. This phenomenon is known as desensitization.
Thus, one way we can attempt to maintain the effectiveness is by moving the sign and associating the sign with the threat of enforcement nearby. It makes sense to use a face instead of words. We process the symbol more quickly, we react more emotionally, and there are no language barriers. The next step is using science to test if it can be a lasting solution.