Revisiting Hägerstrand’s time-geographic framework for individual activities in the age of instant access

1. Introduction Individual human activity takes place in a particular space-time context. Space and time therefore are two major factors that constrain an individual from carrying out certain activities (Golledge and Stimson, 1997). Torsten Hägerstrand (1970) proposed a framework to examine the relationships between various constraints and human activities in a space-time context, known as time geography. Adopting an integrated space-time system, time geography uses the concept of a space-time path to describe an individual's trajectory in physical space over time, and the concept of a space-time prism to depict the extent in physical space and time that is accessible to an individual under certain constraints. With these concepts, the framework provides an effective approach to studying human activities in a space-time context. Researchers have frequently used the framework to study spatial and temporal characteristics of human In recent decades, our society experienced rapid developments of information and communication technologies (ICT), such as the Internet, cellular phones, and wireless-enabled personal digital assistants (PDA). ICT enable a different space, which can connect us electronically and transmit information more efficiently than physical space. This space has been named virtual space or cyberspace in the literature (Janelle and Hodge, 2000). With the help of ICT, people now enjoy new freedom in space and time to carry out activities and interact with others. For example, using cellular phones, we are no longer constrained to the fixed locations of landline phone services. We can now purchase air tickets or search for literature on the Internet regardless of the open hours of travel agencies and libraries. The new freedom can alter how people carry out their activities and how they interact with others, and may eventually lead to changes in spatial and temporal characteristics of human activities. Therefore, it is crucial to gain a better understanding of spatio-temporal characteristics of human activities in the Age of Instant Access. Hägerstrand's time geography provides an effective framework to study spatial and temporal characteristics of human activities under various constraints. However, the original time-geographic framework focused mainly on human activities in physical space. Therefore, the framework falls short of providing a complete view of human activities with their space-time constraints in the Age of Instant Access. Efforts are needed to extend the current time-geographic framework to deal with activities in both physical and virtual spaces. In this paper, we will re-visit the basic concepts of Hägerstrand's time geography and …