Torsten Hägerstrand

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Torsten Hägerstrand (1916 - 2004) was a Swedish geographer who is mostly known for his work on migration, cultural diffusion and time geography (which will be explained later on). Hagerstränd was a student at the University of Lund and would stay connected to this university for the rest of his life. In 1957 he promoted and became a professor at the Lund University, which he would stay until he officially retired in 1982.

His most important publications are:

-Innovations förloppet ur korologisk synpunkt, 1953, Lund: Gleerup. Vertaald door Allan Pred in het Engels als Innovation diffusion as a spatial process, University of Chicago Press, Chicago, 1967

-Migration and area, in: D. Hannerberg, T. Hägerstrand and B. Odeving (eds), Migration in Sweden: a symposium, Lund Studies in Geography, Series B, no. 13, Lund, Gleerup, 1957, p. 27-158.

-On Monte Carlo simulation of diffusion, in: W.L. Garrison and D.F. Marble (eds), Quantitative geography, Vol. 1, Northwestern University Studies in Geography, 13, Evanstone, 1967, p. 1-33

-What about people in regional science? In: Papers Regional Science Association, 24, 1970, p.7-21

-Information systems for regional development – a seminar, Lund Studies in Geography, Series B, no. 37, Lund, Gleerup, 1971

-Diorama, path and project, TESG, 73, 1982, p. 323-339

Time geography

In his theory of time geography (Hägerstrand, 1970), Hägerstand shows how people travel through time and space. People are not free to do so, they always have to deal with decisions they made earlier (historical setting) and some constraints. These constraints can be divided into three groups: capability constraints, coupling constraints and authority constraints.

Capability constraints are biological and instrumental of nature. Examples are sleeping, eating and the possibility to make use of a certain modality. For instance a person can´t travel through time and space, without making stops to eat. Coupling constraints have to do with the presence of persons or materials that certain activities require. For instance you can´t play soccer, if you haven´t got a team to play with. Authority constraints refer to certain institutions which determine wheter you can perform a certain activity or not. For instance opening times of stores determine when you can go shopping and having a drivers license or not determines wheter you may drive a car or not.

When people travel through space and time, they do that to complete projects. A project consists of a serie of tasks and leads to the achievement of a goal. Projects include people, resources, space and time and in order to complete projects, people must overcome their constraints. When participating in a project, an individual may be temporarily inaccessible to another individual. As a consequence, the latter may have to change his or her plans (his or her project). This is called a spread effect.

In his paper on everyday regionalizations, Werlen (2009) refers to this theory in te following way: “[…] it is emphasized that people cannot but always be embodied or situated in time and space, as in the formulations of Torsten Hägerstrand’s time-geography, and that through proximate face-to-face interactions, as well as now through mediated inter-actions over longer distances, they build up pictures of the geographies that they are inhabiting, suffusing them with meanings […] and therefore create a symbolically charged grounding […] that is central to all manner of ensuing economic, political, and cultural activities, events and processes.”

Sources:

- Academmic Dictionaries and Encyclopedias (n.d.). Torsten Hägerstrand. Geraadpleegd op 27 september 2010, op http://en.academic.ru/dic.nsf/enwiki/907802

- Hägerstrand, T. (1970). What about people in regional science? Papers of the regional science associaton, vol. 24, pp. 7-21.

- Werlen, B. (2009). Everyday Regionalizatons. Elsevier.