Joshua A. Reyes

Some of My Projects

My work has combined bits from computer science, economics, and psychology but derives most of its inspiration from mathematics and common experience. Below are summaries of a few of the research projects I’ve worked on in the past.

Social Dilemmas

Social dilemmas capture situations in which individual interests are at odds with group goals. In this project I investigated two classic social dilemmas: the Traveler’s Dilemma and the Minimum-effort Coordination Game. In the first game, classical game theory predicts unrealistic however rational behavior that is unrealized in laboratory trials. In the second game, the theory makes no predictions at all. Somehow people seem to make good decisions anyway.

Under the direction of Tim Killingback, I modeled these dilemmas using proportional imitation learning and smoothed adaptive dynamics to reproduce on paper how people behave in practice. We added the assumption that, at least in these situations, individuals believe that effect varies continuously with cause.

Urban Residential Segregation

Residential segregation is a measure of social clumping in an urban environment. It has different meanings depending on the specific form and structure of the city, and its categories include income, class and race. More often than not, the effects of segregation on cities are overwhelmingly negative. While at the Santa Fe Institute, I teamed up with urban planner Flavia Feitosa and architect Walter Zesk, to model possible causes of urban residential segregation by household income.

Only two parameters drive our model: the distribution of inequality in income and what we called the culture of the city. All households in our cities tried to balance nearness to the city center, where the jobs are, and the niceties of their neighborhood—like good schools, police, public parks, and other public goods. This balance is the culture. Individuals look for the (culturally) best location they can afford.

Bacterial Communities in the Human Microbiome

In sheer number of cells, we are 90% bacteria and only 10% human. The bacterial communities that inhabit us—collectively known in science circles as the human microbiome—can act as friend or foe. Bacteria help digest our food, guard against infectious agents, and keep our immune system running smoothly. While in the Systems Biology PhD program at Harvard Medical School, I worked in the Huttenhower Lab to investigate the structure of these complex communities using large-scale DNA sequencing and a lot of computing power.