Maurizio Porfiri

A hidden link between impulsivity and obesity may not be fixed in human biology but shaped by the cities we live in.

Using a novel engineering-based approach, researchers from NYU Tandon School of Engineering and Italy's Istituto Superiore di Sanità found that attention-deficit/hyperactivity disorder (ADHD) contributes to obesity not only directly through known biological pathways but also indirectly, by reducing physical activity. The findings are published in PLOS Complex Systems.

Obesity prevalence is also influenced by other city-level variables, such as access to mental health services and food insecurity, thereby opening the door to potential mitigation strategies.    

To uncover the nexus between ADHD and obesity, the research team applied urban scaling laws — a mathematical framework from complexity science — to public health data from 915 U.S. cities. Urban scaling describes how features of cities change with population size, similar to how biological traits scale with body size.

They found that both ADHD and obesity decrease sublinearly with population: as cities grow, per-capita prevalence declines. Meanwhile, access to mental health providers and college education rises superlinearly, increasing faster than city size. Larger cities, it seems, offer not just more services, but disproportionately more support for conditions linked to impulsivity.

But size alone doesn’t tell the full story. To reveal where cities over- or underperform relative to expectations, the researchers used Scale-Adjusted Metropolitan Indicators (SAMIs). SAMIs measure how much a city deviates from what urban scaling would predict — highlighting, for example, when a small city has unusually low obesity rates or when a large one falls short on mental health access. These deviations became the foundation for a causal analysis.

"Urban scaling and causal discovery methods allow us to see relationships that traditional health research might miss," explains Maurizio Porfiri, senior author on the PLOS paper. Porfiri is an NYU Tandon Institute Professor with appointments in the Departments of Mechanical and Aerospace Engineering, Biomedical Engineering, Civil and Urban Engineering, and Technology Management and Innovation. He also serves as Director of the NYU Center for Urban Science + Progress (CUSP).

"Without accounting for how city size naturally affects health metrics, we’d misattribute success or failure to the wrong factors. By filtering out these population effects first, we can identify the true causal pathways linking ADHD to obesity — and more importantly, how urban environments modify these relationships,” adds Tian Gan, Ph.D. student in Mechanical Engineering at NYU Tandon. Simone Macrì, senior scientist at the Istituto Superiore di Sanità in Rome, further comments that “This approach reveals precise intervention points that wouldn’t be apparent otherwise"

Using SAMIs, the team mapped a network of interrelated variables: ADHD prevalence led to higher physical inactivity, which in turn increased obesity. Access to mental health care helped reduce inactivity, indirectly lowering obesity risk. Higher prevalence of college education correlated with better mental health access and more physical activity.

This causal map revealed a dynamic system in which impulsivity, health behaviors, and urban infrastructure interact — and cities themselves either reinforce or weaken these effects.

These patterns weren’t uniform. When the researchers mapped SAMIs by region, cities in the Southeastern and Southwestern U.S. consistently showed greater disparities. Neighboring cities often displayed striking differences in ADHD and obesity prevalence, mental health access, and food insecurity — suggesting that local policy, culture, and resources may either amplify or buffer these behavioral health risks.

“Regional averages can mask a lot of variation,” Porfiri said. “The SAMIs let us see which cities are punching above or below their weight. It’s not just about how big a city is — it’s about how it uses its resources. With this kind of insight, policymakers can target investments in mental health care, education, and physical activity to break the link between ADHD and obesity where it's strongest.”

To validate the findings at a more granular level, the team analyzed data from over 19,000 children across the U.S. from the National Survey of Children’s Health. The same causal patterns held: children with more severe ADHD were more likely to be obese, especially when physical activity and household education were low.

The study follows earlier work by Porfiri and collaborators using urban scaling to explore firearm ownership and gun violence across U.S. cities. That research revealed that New York City, despite its large size, significantly outperforms expectations on public safety—underscoring how city-level deviations can challenge assumptions about scale and risk.

In addition to Porfiri, Gan, and Macrì, Rayan Succar, a doctoral candidate in Mechanical Engineering working under Porfiri’s advisement, is also an author on the paper.

The research was supported by funding from the U.S. National Science Foundation and the European Union’s Horizon 2020 programme.

Gan T, Succar R, Macrì S, Porfiri M (2025) Investigating the link between impulsivity and obesity through urban scaling laws. PLOS Complex Syst 2(5): e0000046. https://doi.org/10.1371/journal.pcsy.0000046

A new study offers hope for people who are blind or have low vision (pBLV) through an innovative navigation system that was tested using virtual reality. The system, which combines vibrational and sound feedback, aims to help users navigate complex real-world environments more safely and effectively.

The research from NYU Tandon School of Engineering, published in JMIR Rehabilitation and Assistive Technology, advances work from John-Ross Rizzo, Maurizio Porfiri and colleagues toward developing a first-of-its-kind wearable system to help pBLV navigate their surroundings independently.

“Traditional mobility aids have key limitations that we want to overcome,” said Fabiana Sofia Ricci, the paper’s lead author and a Ph.D. candidate in NYU Tandon Department of Biomedical Engineering (BME) and NYU Tandon’s Center for Urban Science + Progress (CUSP). “White canes only detect objects through contact and miss obstacles outside their range, while guide dogs require extensive training and are costly. As a result, only 2 to 8 percent of visually impaired Americans use either aid.”

In this study, the research team miniaturized the earlier haptic feedback of its backpack-based system into a discreet belt equipped with 10 precision vibration motors. The belt's electronic components, including a custom circuit board and microcontroller, fit into a simple waist bag, a crucial step toward making the technology practical for real-world use.

The system provides two types of sensory feedback: vibrations through the belt indicate obstacle location and proximity, while audio beeps through a headset become more frequent as users approach obstacles in their path.

"We want to reach a point where the technology we’re building is light, largely unseen and has all the necessary performance required for efficient and safe navigation," said Rizzo, who is an associate professor in NYU Tandon’s BME department, associate director of NYU WIRELESS, affiliated faculty at CUSP and associate professor in the Department of Rehabilitation Medicine at NYU Grossman School of Medicine.

"The goal is something you can wear with any type of clothing, so people are not bothered in any way by the technology."

The researchers tested the technology by recruiting 72 participants with normal vision, who wore Meta Quest 2 VR headsets and haptic feedback belts while walking around NYU's Media Commons at 370 Jay Street in Downtown Brooklyn, an empty room with only side curtains.

Through their headsets, the participants experienced a virtual subway station as someone with advanced glaucoma would see it - with reduced peripheral vision, blurred details, and altered color perception. The environment, created with Unity gaming software to match the room's exact dimensions, allowed the team to determine how well participants could navigate using the belt's vibrations and audio feedback when their vision was impaired.

"We worked with mobility specialists and NYU Langone ophthalmologists to design the VR simulation to accurately recreate advanced glaucoma symptoms," says Porfiri, the paper’s senior author, CUSP Director and an Institute Professor in NYU Tandon’s Departments of BME and Mechanical and Aerospace Engineering. "Within this environment, we included common transit challenges that visually impaired people face daily - broken elevators, construction zones, pedestrian traffic, and unexpected obstacles."

Results showed that haptic feedback significantly reduced collisions with obstacles, while audio cues helped users move more smoothly through space. Future studies will involve individuals with actual vision loss.

The technology complements the functionality of Commute Booster, a mobile app being developed by a Rizzo-led team to provide pBLV navigation guidance inside subway stations. Commute Booster “reads” station signage and tells users where to go, while the haptic belt could help those users avoid obstacles along the way.

In December 2023, the National Science Foundation (NSF) awarded Rizzo, Porfiri, and a team of NYU colleagues a $5 million grant via its Convergence Accelerator, a program whose mission includes supporting the development of assistive and rehabilitative technologies. That grant, along with others from NSF, funded this research and also supports Commute Booster’s development. In addition to Ricci, Rizzo and Porfiri, Lorenzo Liguori and Eduardo Palermo are the paper’s authors, both from the Department of Mechanical and Aerospace Engineering of Sapienza University of Rome, Italy. 

Ricci F, Liguori L, Palermo E, Rizzo J, Porfiri M
Navigation Training for Persons With Visual Disability Through Multisensory Assistive Technology: Mixed Methods Experimental Study
JMIR Rehabil Assist Technol 2024;11:e55776
DOI: 10.2196/55776

A new study from NYU Tandon School of Engineering suggests that when it comes to visualizations of mass shooting data, political ideology plays a more significant role in shaping emotional responses than racial identity. The research challenges assumptions about how people interpret data related to gun violence.

The study involved 450 participants who were shown visualizations — in this case, bar charts — of mass shooting victim data highlighting different racial groups. Contrary to the researchers' expectations, participants did not show stronger emotional responses when viewing data about victims of their own race.

"We anticipated seeing evidence of racial homophily, the tendency for people to identify more strongly with members of their own group," said Poorna Talkad Sukumar, a postdoctoral associate in NYU Tandon’s Technology Management and Innovation Department and the lead author on the research which will be presented at VIS2024 next month. "But our findings suggest that the gravity of mass shootings as a topic may override such in-group preferences."

Instead, the study found that political views were the strongest predictor of how participants reacted emotionally to the visualizations. Those with more liberal political leanings tended to have more negative emotional responses across all conditions.

Oded Nov, the NYU Tandon Morton L. Topfer Professor of Technology Management and a member of NYU Tandon’s Center for Urban Science and Progress (CUSP), is another author of the paper. He said the findings highlight the complex interplay between personal beliefs and data interpretation. "This research underscores how pre-existing ideological frameworks can shape our emotional reactions to information, even when presented in a seemingly neutral, visual format.”

Maurizio Porfiri, Director of CUSP and an Institute Professor in the Department of Mechanical and Aerospace Engineering and in the Department of Biomedical Engineering, is also an author of the paper. He suggested that “studies like this are critical to helping us identify best practices to present data on firearm violence and sensitize the general public about firearm-related harms.”

The study also revealed that even relatively simple bar charts elicited strong negative emotions from participants, regardless of their race or the racial group highlighted in the data. This finding could have implications for how sensitive topics are visually presented in media and public policy discussions.

The researchers note that their study had limitations, including a relatively small sample size, which limits the detection of subtle effects. They call for further research exploring different types of societal issues and visualization designs to better understand how viewer characteristics interact with data presentation.

As debates around gun violence and racial disparities continue to occupy national attention, this study offers valuable insights into how Americans process related information. It suggests that bridging ideological divides may be more crucial than addressing racial differences when it comes to fostering a shared understanding of mass shooting data.

This study contributes to Porfiri, Nov, and colleagues’ ongoing data-based research related to U.S. gun prevalence and violence, which they are pursuing under a 2020 $2 million National Science Foundation grant to study the “firearm ecosystem” in the United States. Prior published research under the grant explores:

• the role that population size of cities plays on the incidences of gun homicides, gun ownership and licensed gun sellers;
• motivations of fame-seeking mass shooters;
• factors that prompt gun purchases;
• state-by-state gun ownership trends; and
• forecasting monthly gun homicide rates.

arXiv:2408.03269v1 [cs.HC] 6 Aug 2024

In the world of social creatures, from humans to ants, the spread of behaviors through a group — known as social contagion — is a well-documented phenomenon. This process, driven by social imitation and pressure, causes individuals to adopt behaviors observed in their peers, often resulting in synchronized mass actions; Think of stampedes, or standing ovations.

Social contagion is a double-edged sword in highly integrated societies. While it facilitates cohesion and collective efficiency, unchecked contagion can lead to detrimental mass behaviors, such as mass panic. Thus, nature has evolved regulatory mechanisms to keep such behaviors in check.

One such mechanism is reverse social contagion. In reverse social contagions, increased interactions between individuals engaged in a behavior lead to a higher likelihood of them stopping that behavior, rather than engaging in it.

In a new paper published in PNAS Nexus, researchers led by Maurizio Porfiri — NYU Tandon Institute Professor of Professor of Biomedical Engineering, Mechanical and Aerospace Engineering, and Civil and Urban Engineering, as well as the director of its Center for Urban Science and Progress (CUSP) — describe this unique phenomenon in colonies of harvester ants (Pogonomyrmex californicus) in order to understand the energetic consequences of highly integrated social behavior.

“Ants colonies reduce their energy spending per individual as the colony grows, similar to the size-dependent scaling of metabolic costs in birds and mammals discovered by Kleiber almost a century ago,” said Porfiri. “To date, a convincing explanation of how this collective response emerges is lacking.”

Utilizing tracked video recordings of several colonies, they discovered that individual ants did not increase their activity levels in proportion to the colony size. This was a curious finding, because larger colonies means more interactions between their members, and more opportunities for reinforcing behaviors.

To decode this behavior, the team — who also includes Pietro De Lellis from the University of Naples, Eighdi Aung and (Tandon alum) Nicole Abaid from Virginia Tech, Jane S. Waters from Providence College, and Santiago Meneses and Simon Garnier from the New Jersey Institute of Technology — applied scaling theories typically used to study human settlements. They derived relationships linking colony size to interaction networks and activity levels, hypothesizing that reverse social contagion was at play. Their hypothesis was supported by respirometry data, which revealed a potential connection between ant activity and metabolism.

Imagine you are an ant, and you see one of your fellow workers foraging for food. If you are governed by social contagion, you might also begin foraging so you don't look lazy. But the energy you expend foraging might not be worth it if one ant can efficiently gather the food. In this case, reverse social contagion tells you to kick your feet up and relax while you let your compatriot do the work, because you’ll need your energy later for another task. In this way, restraining social contagion makes the colony more efficient.

The study draws a fascinating parallel between insect colonies and human cities. In both systems, social interactions influence energy expenditure, but in opposite directions. Insect colonies exhibit hypometric scaling—activity levels do not increase proportionally with colony size. In contrast, human cities show hypermetric scaling, where energy expenditure grows faster than the population size.

“Human behavior is often driven by personal gain” says Simon Garnier, Associate Professor of Biological Sciences at NJIT and senior author on the paper. “Ants, on the other hand, tend to prioritize the needs of the colony over their own. This has huge implications for understanding the differences between the organization of human and social insect societies.”

Unlike humans, ants manage their energy as a colony rather than individually, somehow displaying a cooperative response. This study shows that ants use reverse social contagion to regulate their overall activity and energy use. Essentially, when many ants are busy with a task, some will stop to prevent the entire colony from overworking. This behavior aligns with scaling laws and metabolic patterns seen in other biological systems.

In simpler terms, think of an ant colony as one big organism where every ant's actions are coordinated for the colony's benefit, not just their own. Future research will look into how exactly these ants communicate and manage their energy so efficiently.

This research not only sheds light on the regulatory mechanisms in ant colonies but also offers insights into the broader principles of social regulation across species. As we continue to explore these parallels, we may uncover more about the fundamental dynamics that govern both natural and human-made systems.

“This is the first step we are taking to understand and model energy regulation in ant colonies,” said Porfiri. “Is energy regulation accompanied by improved performance for the collective? Can we design algorithms for robot teams inspired by ants that can maximize performance and minimize energy costs? Can we learn some lessons for our city transportation networks? These are just some of the questions we would like to address next. ”

This work was funded in part by a $3 million grant from the National Science Foundation, which over five years will aim to create a new paradigm for a better understanding of how loosely connected units can nonetheless collectively maintain function and homeostasis.

Porfiri, M., De Lellis, P., Aung, E., Meneses, S., Abaid, N., Waters, J. S., & Garnier, S. (2024). Reverse social contagion as a mechanism for regulating mass behaviors in highly integrated social systems. PNAS Nexus, 3(7). https://doi.org/10.1093/pnasnexus/pgae246