As one of several related concepts developed by Guy Debord (1981a, 5) and other members of the Lettrist International (1952–57) and the Situationist International (1957–72), psychogeography, to cite the 1955 text in which it first appeared in print, is ‘the study of the precise laws and specific effects of the geographical environment, whether consciously organized or not, on the emotions and behavior of individuals’.

As it stands, this definition is somewhat misleading, for it is elaborated in the context of a ‘critique of urban geography’ that aims not simply to investigate the effects of ‘present-day urbanism’ (typically, the stupefying consumerist pleasures it tends to promote), but to transform the environment (in order to fulfil desires barely yet formed). At its heart is a utopian and often ludic vision of ‘the architecture of tomorrow’ (Chtcheglov 1981, 2) and the ‘groping search for a new way of life’ (Debord 1981a, 5).

One of the key methods of psychogeography is the dérive: a form of pedestrian free-association designed to reveal lines of force and zones of influence normally hidden from those who only know the conventional routines dictated by work or leisure. The dériveur (alone, but preferably in several small groups) would record the different ambiences observed on the walk, and through a process of cross-checking designed to produce more accurate conclusions, construct maps and diagrams which consolidate their findings and form the basis of future activity. But the practice of the dérive itself is already transformative, at least for those taking part, disrupting their own habitual responses to the city they traverse (Debord 1981b), and as such is an example of détournement, a more general technique by which existing (and often commonplace) objects, texts, images and rituals are recontextualized to create disorienting effects (Debord and Wolman 1981).

To the extent that psychogeography resembled a field of study that aspired to a degree of cartographical objectivity (see cartography), its proponents failed to acknowledge the extent to which different social relations will produce radically diverse interpretations of one's surroundings, a tendency that was reinforced by their emphasis on the built environment, fondness for aerial views and recommendation that research should be conducted by small numbers of like-minded people.