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                   White Paper

Introduction to the World of Information Foraging


Information Foraging juxtaposed with Food Foraging

Why Information Foraging came into existence

Information Foraging Theory

  • Information Patches

  • Information Scent and Information Diet



Abhijit Rao

Department of Computer Engineering

Manipal Institute of Technology




Information Foraging Theory is an approach to understanding how strategies and technologies for information seeking, gathering, and consumption are adapted to the flux of information in the environment. The theory assumes that people, when possible, will modify their strategies or the structure of the environment to maximize their rate of gaining valuable information.

Humans actively seek, gather, share, and consume information to a degree unapproached by other organisms. Information Foraging tasks require increasingly sophisticated information-gathering, sense-making, decision-making, and problem-solving strategies.

The structure of the interface between people and information repositories in the external world determines the time costs, resource costs, and opportunity costs of different information foraging and sense-making strategies. Such costs include access, recognition, and handling costs, which can be weighed against the rate at which useful information is delivered to an embedding task.

Our basic assumption is that people will modify their strategies, or modify the structure of the interface if it is malleable, in order to maximize their rate of gaining valuable information. A cognitive strategy will be superior to another if it yields more useful information per unit cost.


Information Foraging juxtaposed with Food Foraging

Birds of prey are always face a recurrent problem of deciding what to eat, and we assume that its fitness, in terms of reproductive success, is dependent on energy intake. Metabolic activity of the birds is largely dependent on its intake. Energy flows into the environment and comes to be stored in different forms. For that bird, different types of habitat and prey will yield different amounts of net energy (energetic profitability) if included in the diet.

Furthermore, the different food-source types will have different distributions over the environment. This means that the different habitats or prey will have different access or navigation costs.

For example, if the bird decides fish as its diet than it might have to fly some distance before it encounters a water-source with fish as its inhabitants. Different species of birds of prey might be compared on their ability to extract energy from the environment. Birds are better adapted if they have evolved strategies that solve the problem of maximizing the amount of energy returned per amount of effort.

Information flows into the environment and are represented in different types of external media, such as books, manuscripts, or on-line documents. The different information sources (or repositories) will have different profitabilities, in terms of the amount of valuable information returned per unit cost in processing the source. In addition, the different kinds of sources will be distributed in the task environment in different ways. Some will be more prevalent, or less effortful to access, than others. Conceptually, the optimal information forager is one that best solves the problem of maximizing the rate of valuable information gained per unit cost, given the constraints of the task environment.


Why Information Foraging came into existence

Technological innovation has lead to an explosive growth of recorded information.

  • The number of scientific journals has been growing by about a factor of 10 every 50 years since the 18th century. The number of Internet hosts has been doubling about every year since 1992.
  • The number of pages accessible from a computer user’s desktop has increased about five orders of magnitude in the last five years.
  • Computer users world-wide now have desktop access to more than 275 million publicly accessible World Wide Web (WWW) pages, growing at the rate of 7.5 pages every second. Similar, if less spectacular, observations could be made for other information sources.

Such growth triggers (and is triggered by) adaptations in human information technology, since human minds, although growing in number, are limited in their ability and available time to keep pace. Providing people with access to more information is not the problem.


Information Foraging Theory

Information foraging theory is an approach to understanding how user strategies and technologies for information seeking, gathering, and consumption are adapted to the flux of information in the environment. The framework borrows from biology, and especially from the field of optimal foraging theory.

Information Patches

 The task environment of an information forager often has a “patchy” structure. Information relevant to a person’s information needs may reside in piles of documents, file drawers, bookshelves, libraries, or in various on-line collections. Often the information forager has to navigate from one information patch to another—perhaps from one WWW site to another, or from one search engine result to another. The person is faced with decisions such as the allocation of time among patch foraging tasks.

 Information Scent and Information Diet

 Information foraging often involves navigating through spaces (physical or virtual) to find high-yield patches. For instance, imperfect information at intermediate locations is used by the forager to decide on paths through a library or an on-line text database to target information. Such intermediate information has been referred to as “residue”. In keeping with foraging terminology, we have called this scent. Information scent is the (imperfect) perception of the value, cost, or access path of information sources obtained from proximal cues, such as WWW links. For example, on a Web page, information scent may be delivered by link descriptors, images, contextual clues, such as preceding headings, or by page arrangement. Our notion is that the proximal perception of information scent is used to assess the profitability and prevalence of information sources. These scent-based assessments inform the decisions about which items to pursue to maximize the information diet of the forager. Our protocol analysis methodology is aimed in part at codifying information scent, and we will analyze the effects of information scent on WWW behaviors.


Information Foraging Theory frames the analysis of complex ensembles of cognitive mechanisms and knowledge that are shaped by information foraging environments. Information Foraging Theory focuses on understanding adaptation to current environments. The theory could also provide the scientific basis from which we might engineer innovations that enrich the information that people process.


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Card, S.K., Pirolli, P., Wege, M.V., Morrison, J.B., Reeder, R.W., Schraedley, P.K., Boshart, J., 2001, Information Scent as a Driver of Web Behavior Graphs: Results of a Protocol Analysis Method for Web Usability, CHI 2001, 31 MARCH – 5 APRIL, 498-505.

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