Researchers at MIT have created an online tool to help discover what effect urban looks have on people's perception of a city's safety or their own prosperity.

By placing images of selected cities taken randomly from Google StreetView side by side, the Place Pulse tool was used in a study to allow users to compare and choose the photo they thought came closest to matching certain attributes. They were asked to rank locations by answering one of three questions—"Which Place Looks Safer?", "Which Place Looks More Upper-Class?" or "Which Place Looks More Unique?". The answers were then algorithmically compiled to give areas a score out of ten for each of the attributes, which were then transformed into maps.

Photos were drawn from four cities—New York and Boston in the US, and Linz and Salzburg in Austria. Researchers discovered a greater disparity between extremes for class and safety in the US cities than in the Austrian cities.

One limitation of the tool is that most of the photos were captured by Google very early in the morning, meaning many areas are almost completely empty of people and traffic, which could give a false impression.

The tool does, however, help to plug some of the holes in the "broken-windows theory," a popular but oft-criticized idea developed by two Harvard researchers in the early 80s. The theory suggests that visible signs of neglect in an area instills the idea that no one around is in charge or cares, which in turn initiates crime, perpetuating a cycle of further neglect and crime. It was a theory which former New York mayor Rudy Giuliani used as a basic strategy for tackling crime, but one criticism of the theory suggests that it's impossible to quantify subjective things like visible disorders.

By asking users to make observations about areas on the basis of linking photographs to subjective attributes, the data produced by the tool can be used to create color-coded maps based on people's perceptions. Those maps can then be compared directly with maps that show the prevalence of crime across a city, for example. In the paper published by the research team, it was discovered that perceptions of unsafe areas correlated strongly with incidence of violent crime in New York.

Researchers hope the tool will be used by social scientists and policy makers to understand more closely what city dwellers feel about their environments and guide decisions regarding investment, urban planning, and tackling crime.

"One of the things that would be the most interesting in the long run is to overlay these maps with expenditures of government, narrowly defined by the things that affect how places look, such as repaving roads, building parks, or putting cables underground," said César Hidalgo of MIT and Macro Connections who led the study.

A second study is already underway using the tool—this time users are being asked to compare pictures based on five different attributes across 56 cities. It's hoped that the data collected will be used to create algorithms that can help identify which features in the images elicit which kinds of responses.

This story originally appeared on Wired UK.