There is substantial evidence that populations in the Western world exhibit a local bias compared to East Asian populations that is widely ascribed to a difference between individualistic and collectivist societies. However, we report that traditional Himba--a remote interdependent society--exhibit a strong local bias compared to both Japanese and British participants in the Ebbinghaus illusion and in a similarity-matching task with hierarchical figures. Critically, we measured the effect of exposure to an urban environment on local bias in the Himba. Even a brief exposure to an urban environment caused a shift in processing style: the local bias was reduced in traditional Himba who had visited a local town and even more reduced in urbanised Himba who had moved to that town on a permanent basis. We therefore propose that exposure to an urban environment contributes to the global bias found in Western and Japanese populations. (Contains 3 figures.)