What is Psychogeography?

"The study of specific effects of the geographical environment, consciously organised or not, on the emotions and behaviour of individuals." – Preliminary Problems in Constructing a Situation in Situationniste Internationale No.1 (1958) [1]

We passed the site of the London Psychogeographical Association and were left slightly dazed at some of the pages. See for example the definition of "the" and "Theist" [2]. – Bo Leuf

I am never quite sure whether this sort of thing is (1) a variety of performance art (Dadaistic in nature) ... or (2) at attempt at serious political commentary ... or (3) merely the product of some seriously muddled minds. (I tend to incline toward the first and last hypotheses.) The Google Web Directory entry "Society > Politics > Anarchism > Situationism > Psychogeography" [3] suggests some other readings on the topic, but the ones I've glanced at do not enlighten much. — MarkZimmermann

(correlates: FocusAndFanout, LiberalArts, The Unreasonable Effectiveness of Mathematics, ...)