title: The collaborative image of the city: mapping the inequality of urban perception.
abstract: 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.
authors.affiliation: The MIT Media Lab, Massachusetts Institute of Technology, Cambridge, Massachusetts, United States of America.
authors.forename: Philip
authors.initials: P
authors.lastname: Salesses
authors.forename: Katja
authors.initials: K
authors.lastname: Schechtner
authors.forename: César A
authors.initials: CA
authors.lastname: Hidalgo
mesh_terms: D001317:Austria; D002947:Cities; D006801:Humans; D007182:Income; D010465:Perception; D010679:Philippines; D012959:Socioeconomic Factors; D014481:United States; D014505:Urban Population
references.citation: Nature. 2006 Jan 26;439(7075):462-5
references.pmid: 16437114
references.citation: Proc Natl Acad Sci U S A. 2009 Sep 8;106(36):15274-8
references.pmid: 19706491
references.citation: Am J Public Health. 2000 Feb;90(2):230-6
references.pmid: 10667184
references.citation: Proc Natl Acad Sci U S A. 2007 Apr 24;104(17):7301-6
references.pmid: 17438298
references.citation: Proc Natl Acad Sci U S A. 2007 May 1;104(18):7332-6
references.pmid: 17456605
references.citation: Biometrika. 1950 Jun;37(1-2):17-23
references.pmid: 15420245
references.citation: J Health Soc Behav. 2001 Sep;42(3):258-76
references.pmid: 11668773
references.citation: Nature. 2007 Apr 5;446(7136):664-7
references.pmid: 17410175
references.citation: Science. 2008 Dec 12;322(5908):1681-5
references.pmid: 19023045
references.citation: Nature. 2008 Jun 5;453(7196):779-82
references.pmid: 18528393
references.citation: Sci Rep. 2013;3:1376
references.pmid: 23524645
references.citation: Science. 2010 May 21;328(5981):1029-31
references.pmid: 20489022