Car-Free Cities Are the Future, Biometrics Reveal
Until now it has been impossible to peer into the human mind, but new biometric and machine learning tools are changing this. We can now understand how people experience cities, and these insights can provide a roadmap for creating more just, sustainable and healthy places.
Assuming people approve of these technologies surveilling them, researchers like us can collect real-time facial analysis and eye-movement data using webcams. We can then discern subconscious information communicated by people’s faces when they are engaged with different urban scenes. For example, did they smile? What did they look at first? How long were they engaged with what they saw?
Our research group at Tufts University has conducted a number of facial analysis and eye-tracking studies, and sifting through these data we see that people do not like looking at cars. Conventional urban design and planning practice relies on people’s subjective assessments of places they spend time in through surveys or interviews. This new kind of information and other examinations of how people perceive their environments could revolutionize the way we design urban developments because we believe we can better take into account people’s preferences before we start planning how they will use and navigate them.
This research builds on previous work establishing the social and health benefits of car-free urban spaces, but employs a biometric lens; by measuring unconsious reactions to different scenes, we now have empirical evidence of the harm caused just by seeing cars. These results reinforce other research that likewise demonstrates the value of using eye-tracking and facial expression analysis to guide urban design and planning.
While the range of factors governing our reaction to space is as vast as the range of human emotion itself, our most recent project uncovered a statistically significant increase in positive emotions when people viewed urban streets without cars versus ones with cars on them: people appear to be happier when cars aren’t in the picture—literally. This research helps us to quantify the benefits of car-free spaces when urban planners are considering how to make their cities more welcoming and pedestrian-friendly.
For this study of car-free streets, we used iMotions Online AFFDEX facial coding software to track 51 participants’ real-time visual attention and facial expressions in response to images and videos of Memorial Drive in Cambridge, Mass. This is a popular street closed to vehicle traffic on weekends during certain times of the year. We captured similar images of the same stretch of road with and without cars and compared our participants’ emotional reactions to both types of images. The system records a person’s eye movements and facial expressions with a camera. Then the software uses an algorithm to score whether a participant displayed positive, negative or neutral emotions during each millisecond of the study based on subtle movements in their facial muscles.
Although our participants expressed neutral emotions in response to the images 85 percent of the time, participants spent on average 0.4 percent more time expressing positive emotions in response to vehicleless images and videos. While seemingly a small difference, any measurable effect from a still image can signal something worth considering in a real-world setting where people are surrounded by cars.
To further explore whether these differences were meaningful, we compared both emotional responses and visual fixation patterns in response to vehicle-free spaces by using a statistical method that allowed us to control for possible confounding factors. People in the study spent more time showing positive emotions when they looked at images without a vehicle in the foreground compared to images with cars. In addition, our eye-tracking data showed that people’s eyes spent more time on the areas of images where vehicles are present rather than absent. People’s eyes are drawn to cars, but their emotional responses are more negative while looking at them.
Scientists and urban planners globally are beginning to tinker with biometric tools to understand these kinds of behavioral responses to urban and architectural elements. They are finding that ornate facades and active ground floors that encourage pedestrian activity tend to be most effective in attracting visual attention. Other studies demonstrate that front porches, vernacular architecture, which is architecture designed according to local customs, and pedestrian-scaled design draw our eyes. Some studies have taken these biometric tools out of the lab, but more work is still needed to test these human behavioral responses in real-world conditions.
In Boston, a city that has long explored car-free streets, the mayor shut down more streets to car traffic in the early days of the COVID pandemic to give people places to go outside. These Open Streets events were highly successful in getting people to spend time out of their homes. Other scholars’ research demonstrated the health benefits of car-free urban design, but, until now, none have used biometrics to show how cars affect our emotions.
Humans have evolved to survive in dangerous environments. Our nervous system responds to stimuli—especially hand motions, faces and voices—and helps us decide if we are in a safe or dangerous situation. In social contexts familiarity further enforces safety and helps us interpret the facial features of another person as warm or friendly. All the elements one encounters play a role in our perception of a space that may be considered threatening. For example, recent research explains how “conviviality,” or the “friendliness” of a space, is more challenging to foster in a car-centric environment.
Natural elements like trees and shrubs are less foreign to our brain than car-related infrastructure like roadways and curbs, and align more with our innate preferences, according to our findings and other research. Furthermore, natural design elements make it easier for humans to relax and enjoy their surroundings as they reflect the natural surroundings of our environment. Car-free spaces are important in community building. This new research is helping to demonstrate that and strengthen the case for more of them.
This is an opinion and analysis article, and the views expressed by the author or authors are not necessarily those of Scientific American.