The Collaborative Image of The City: Mapping the Inequality of Urban Perception

A traveler visiting Rio, Manila or Caracas does not need a report to learn that these cities are unequal; she can see it directly from the taxicab window. This is because in most cities inequality is conspicuous, but also, because cities express different forms of inequality that are evident to casual observers. Cities are highly heterogeneous and often unequal with respect to the income of their residents, but also with respect to the cleanliness of their neighborhoods, the beauty of their architecture, and the liveliness of their streets, among many other evaluative dimensions. Until now, however, our ability to understand the effect of a city's built environment on social and economic outcomes has been limited by the lack of quantitative data on urban perception. Here, we build on the intuition that inequality is partly conspicuous to create quantitative measure of a city's contrasts. Using thousands of geo-tagged images, we measure the perception of safety, class and uniqueness; in the cities of Boston and New York in the United States, and Linz and Salzburg in Austria, finding that the range of perceptions elicited by the images of New York and Boston is larger than the range of perceptions elicited by images from Linz and Salzburg. We interpret this as evidence that the cityscapes of Boston and New York are more contrasting, or unequal, than those of Linz and Salzburg. Finally, we validate our measures by exploring the connection between them and homicides, finding a significant correlation between the perceptions of safety and class and the number of homicides in a NYC zip code, after controlling for the effects of income, population, area and age. Our results show that online images can be used to create reproducible quantitative measures of urban perception and characterize the inequality of different cities.

前往里约热内卢、马尼拉或加拉加斯的旅行者无需借助调查报告便能知晓这些城市存在不平等现象——只需透过出租车车窗便能直观窥见。这是因为在多数城市中，不平等现象醒目直观，同时城市所呈现出的各类不平等形式也能被普通观察者轻易察觉。城市具有高度异质性，在居民收入、社区整洁度、建筑美感与街道活力等诸多评价维度上，往往都存在不平等现象。然而迄今为止，由于缺乏关于城市感知的量化数据，我们理解城市建成环境对社会与经济结果影响的能力始终受限。本研究基于“不平等在一定程度上具有直观性”这一直觉，构建了城市差异的量化测度方法。本研究借助数千张地理标记图像，对美国波士顿、纽约以及奥地利林茨、萨尔茨堡的安全感知、阶层感知与独特性感知进行了测度，结果发现纽约与波士顿的图像所引发的感知跨度大于林茨与萨尔茨堡的图像。我们将此解读为：波士顿与纽约的城市景观相较于林茨与萨尔茨堡，具有更强的差异性，即更不平等。最后，本研究通过探索测度结果与凶杀案数量之间的关联来验证测度方法的有效性：在控制收入、人口、面积与年龄等因素的影响后，纽约各邮政编码区域的安全感知与阶层感知与凶杀案数量之间存在显著相关性。研究结果表明，可借助网络图像构建可复现的城市感知量化测度方法，进而刻画不同城市的不平等特征。