NCGIA Initiative 19 -- GIS and Society: The Social Implications of How People, Space, and Environment Are Represented in GIS

Representing Individuals and Societies in GIS

Catherine Dibble
Department of Geography
University of California
Santa Barbara, CA 93106

INTRODUCTION

An inherent difficulty in representing and understanding individuals and societies in Geographic Information Systems (GIS) has been the static, land-attribute framework of current GIS. Yet societies are dynamic; composed of disparate and mobile individuals whose interactions lead to emergence of the complex, non-linear phenomena that shape our spaces and societies. The very complexity of social phenomena means that harnessing the power of computers to aid our understanding is far more critical here than it is for the simpler landscape issues traditionally addressed with GIS. Our challenge is not merely to clarify the limitations of current computer representations, but rather to elucidate alternative representations that do facilitate effective representation and integration of the complex relationships between People, Space, and Environment.

Individual-Based Models may offer a more appropriate system for representing and studying many complex social interactions within a spatial framework. Such models enable us to specify individuals and populations of individuals who each have distinct knowledge, needs, desires, resources, information access, locations, abilities, mobilities, and time-specific locations; all within a spatial framework that includes not only spatial and environmental context, but also the context provided by other individuals and their potential interactions.

This is not yet GIS: no system that would currently be labeled a “GIS” has these capabilities. Yet such individual-based models do currently exist (Santa Fe Institute: Swarm 1995), and in many ways these systems may offer far deeper insights into human geographic phenomena than any current GIS. Perhaps we should deconstruct our usual labels. ;) Still, there are serious questions related to the appropriate use of the strengths of each, and few venues would be more appropriate than I-19 for a thorough examination of both the potential and limitations of this alternative for representing individuals and societies within a formal framework.

MOTIVATION FOR INDIVIDUAL-BASED MODELS IN HUMAN GEOGRAPHY

Traditional geographic models of human settlement patterns typically address one particular era of economic development and available spatial technologies (e.g. Von Thünen, Christaller, Weber, Lowry). Such “snapshot” models are useful for understanding spatial relationships in a fairly simple and static world of fixed spatial technologies and one dominant economic sector. Yet if we want to understand spatial interactions and patterns in a world that becomes increasingly complex, and where spatial technologies and motivations for interaction change increasingly rapidly, it will help to have a more dynamic and more general model that captures the relationship between different profiles of interactions, geographic structures, and spatial technology alternatives.

Developing a general model such as the one described above is particularly important if we want to try to make any predictions about future geographic patterns. Just what is likely to be the net effect of new spatial technologies such as the Internet and video conferencing? To what extent are the structural-change elasticities with respect to developments in spatial technology dependent on the relative importances of various roles and on the influence of prior structure? Most profoundly, individual-based simulations have the capability to capture non-linear interactions and dynamic feedback effects that may provide more realistic models of spatial processes. For example, to what extent do positive feedback and lock-in mitigate or exacerbate the influences of prior structure or inequalities?

RESEARCH QUESTIONS

Individual-based models may be useful at a number of different scales, for example:
  1. To explore the relationship between changing spatial technologies, shifting economic sector requirements for spatial integration (post-modern economies), and the response of human settlement patterns and associated resource distributions.
  2. To explore social dynamics within neighborhoods and cities at various scales, especially the degree to which isolation or diversity enhance or inhibit the evolution of cooperation and understanding.
  3. To explore the social and economic implications of differential access to specific resources and especially to information technologies, for different groups in different spatial and economic situations.

SAMPLE MODEL FOR SPATIAL TECHNOLOGIES AND SETTLEMENT PATTERNS

Let each agent correspond to one individual human (not groups). Groups of agents may in turn be associated with different social groups, but interaction is fundamentally at the individual level. Initially, each agent is represented by fixed preferences, abilities, mobility, and resource requirements. Information (and derived knowledge) are determined endogenously according to each individual’s access to sources of information, which can include differential access to specific technologies and networks (see the NCGIA Inner-Cities Access Project). Later, adaptive agents may have the capability to modify their behavior according to experience.

I posit that many spatial distributions of individuals can be captured by the following framework, and that there exist secondary evaluations related to fairness, resource allocation, and social and environmental sustainability that may in turn be associated with the distributions that evolve.

  1. landscape, consisting of site and situation
    site
    attribute functions defined over space (either over nodes or over plane)
    situation
    spatial technologies and infrastructure that affect access from a site
    both site and situation may have elements that are either exogenous or endogenous

  2. agents, with access requirements and personal preferences defined over site and situation. Access requirements determine agent types, whereas personal preferences may be distributed randomly (or not) across agents:
    access requirements determine agent types (all models)
    site
    agent requirements for site resources or conditions
    situation
    agent requirements for spatial access to one another and/or to resources
    personal preferences (added to later models) are defined by
    site
    agent preferences over site characteristics
    situation
    agent preferences for spatial access to one another and/or to resources

  3. population characteristics -- the proportions of agent types within the population

  4. rules, pertaining to agent actions and feedback effects
    agent actions
    agent actions as a function of agent perceptions of landscape characteristics and population distribution
    feedback effects
    landscape characteristics as a function of agent actions

  5. prior structure (optional), specified by additional landscape configurations and/or population distributions (includes both proportions and individual location)

QUESTIONS FOR INITIATIVE 19 -- REPRESENTING INDIVIDUALS AND SOCIETIES

With respect to the development of theories about the relationship between economic and social interactions, spatial technologies, and geographic distributions, individual-based simulation models have the potential to provide us with laboratories within which to conduct controlled tests about the effects of alternative specifications of specific individual characteristics, geographies, spatial technologies, and interactions thereof. To what degree do the model’s predictions correspond to what we know about historical conditions and resultant phenomena? Our challenge is to delineate representations and conditions under which individual-based models may provide useful insights with a minimum of distortion or misrepresentation.

REFERENCES

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Catherine Dibble 27 June 2003