Prevention: Environmental and Technological Strategies

Interaction models specify conditional relationships, or scope limiters, whereby other variables soften the determinism of an independent variable. In the case of population density, for example, individuals can be seen as more or less equipped by their personalities or the capital provided by their cultures to cope successfully with crowding (Gillis, Richard, and Hagan). This could account for the inconsistent results reported by more deterministic additive equations examining the relationship between population density and criminal behavior.

Newman's Defensible Space (1972) presented an interaction model applied to the impact of the architectural environment on crime, from an environmental opportunity/constraint perspective. Newman suggested that specific aspects of urban design create unsupervised locations by inhibiting or preventing surveillance and control in neighborhoods, and even within apartment buildings. High walls around buildings, underground parking areas, long corridors, and secluded spaces such as stairwells provide opportunity for deviant or criminal activity. This is because these locations are concealed from formal policing on streets. At the same time, since this space lies outside their own dwelling units, residents do not feel obliged to maintain surveillance on these areas either. Distance from home is inversely related to willingness to intervene (Gillis and Hagan, 1990). As with the perspective developed by the Chicago School, then, Newman's argument accounts for the location of criminal activity, and suggests that structural barriers (in this case architectural) can block the local social ties that are community, permitting increased rates of crime and delinquency. In this respect, Pruitt-Igoe, the infamous public housing project in St. Louis, exemplifies how not to design.

The scale of neighborhoods, projects, and buildings may also contribute to the degree of disorganization and rate of mayhem. Pruitt-Igoe contained a concentration of disadvantaged people. This may have also provided a critical mass of young, criminally disposed males, who were not only able to act as individual offenders, but who coalesced as gangs, creating criminal subcultures with a program of recruitment. In line with this, juvenile residents of high-rises report greater use of illicit drugs than do their counterparts in low-density housing (Gillis and Hagan, 1982). In any case, since the debacle and destruction of Pruitt-Igoe, many communities try to avoid large-scale public housing projects, and follow a program of dispersal instead of concentration.

Interestingly, Newman attaches great importance to the presence of graffiti as an indicator of lapsed control and portentous of future crime. Declines in crime in cities such as New York during the late 1990s are typically explained by civic officials as the result of acting against minor as well as major offenses, including graffiti. This suggests that environmental cues may elicit illegal activity, as noted earlier, but the actual causal sequence here is uncertain. It is also noteworthy that the interaction model can be interpreted as a statement that a causal sequence will not hold under all conditions. Thus, increasing the lighting on streets will not reduce mugging any more than a vault will reduce bank robberies if no offenders are present in the population. Similarly, changing traffic flow by establishing a one-way street will not reduce prostitution in areas where there are neither prostitutes nor johns. On the other side, if Pruitt-Igoe and its surroundings had contained older women instead of young, truly disadvantaged males, the project's crime rate would have been low. The interaction argument is that environmental design can discourage informal social control, and that this will in turn result in increased criminal activity, but only in populations with a propensity to offend in the first place. Thus, criminogenic architecture and planning will have no effect on the crime rate of a population of conformists. However, in a population of risk takers, a crime prevention strategy based on environmental design and increased informal surveillance would make a difference, especially in urban areas. In rural areas and small towns, traditional occupations for husbands and wives revolve around the home, where surveillance is maintained and passersby noticed. In contrast, occupations and routine cosmopolitan activities in modern urban areas frequently draw adults away from home, leaving an unattended store of valuable goods, which may attract burglars (Cohen and Felson), even from the hinterland. In this way, specific areas may produce criminal opportunity more than offender personalities, and by so doing inflate the rate of crime in those environments.

On a broad level, commercial neighborhoods containing too few residences must depend solely on policing for after-hours surveillance. The planning implication here is to avoid desertion after 6 p.m. by zoning for a mix of residential and commercial land use.