Spending as little as 45 minutes in a high-crime, deprived neighborhood can have measurable effects on people's trust in others and their feelings of paranoia（偏执狂）.

In a new study, students who visited high crime neighborhoods quickly developed a level of trust and paranoia comparable to the residents of that neighborhood, and significantly different from that in more low-crime neighborhoods. As a result, urban planners should carefully consider the psychological effects of the environment.

Researchers in the UK studied two neighborhoods of the same city only a few kilometres apart, one economically deprived and relatively high in crime, and the other affluent and relatively low in crime. They initially surveyed the residents and found that the residents of the high-crime neighborhood reported lower feelings of social trust and higher feelings of paranoia than the residents of the other neighborhood. Then, in an effort to understand how these feelings had come to exist, they enrolled over 50 student volunteers (who were not from either neighborhood) and bussed them to one or other neighborhood at random.

The volunteers, who did not know the purpose of the study, spent up to 45 minutes walking the streets and delivering envelopes to houses. Afterwards, the volunteers were also surveyed about their feelings of social trust and paranoia. Those sent to the disorderly neighborhood reported lower trust and higher paranoia than those sent to the affluent（富裕的） neighborhood. Moreover, even after such a brief visit, the visitors to a neighborhood had become indistinguishable from the residents of that neighborhood in terms of their levels of trust and paranoia.

The study, entitled "Being there: a brief visit to a neighborhood induces the social attitudes of that neighborhood" was published in the open access journal, PeerJ, on January 14th.

It was already known that living in a deprived area is associated with poorer mental health and a less trusting outlook. However, the previous correlational studies had not been able to establish causality: do people become less trusting as a response to the deprivation that surrounds them, or do people who were less trusting to start with tend to reside in more deprived areas? It was to try to address this question that the researchers came up with their random 'busing' experiment. Since the volunteers were assigned to the neighborhood at random, any differences in their attitudes after the visit would reflect the psychological effects of the experiences they had just had.

"We weren't surprised that the residents of our high-crime neighborhood were relatively low in trust and high in paranoia," says lead researcher Daniel Nettle of Newcastle University. "That makes sense. What did surprise us though was that a very short visit to the neighborhood appeared to have much the same effects on trust and paranoia as long-term residence there." The results suggest that people respond in real time to the sights and sounds of a neighborhood -- for example, broken windows, graffiti, litter, and razor-wire on houses -- and that they use these cues to update their attitudes concerning how other people will behave. "It's a striking illustration（说明，插图） of the extent to which our attitudes and our feelings are malleable（可塑的） and are powerfully influenced by the social environment that surrounds us on a day-to-day basis. Policy-makers, urban planners, and citizens need to remember this. Improving the quality and security of the urban environment is not just a cosmetic luxury; it could have profound knock-on effects for city-dwellers' social relationships and mental health."