This article was originally published online on 31 March 2010 with errors in the affiliation
designations. AIP apologizes for these errors. All online versions of the article were
corrected on 2 April 2010. The article was correct as it appeared in the printed version of the
journal. The authors and affiliations appear correctly above. a) Electronic mail: bialonski@
gmx. net. b) Electronic mail: klaus. lehnertz@ ukb. uni-bonn. de.

We consider recent reports on small-world topologies of interaction networks derived from
the dynamics of spatially extended systems that are investigated in diverse scientific fields
such as neurosciences, geophysics, or meteorology. With numerical simulations that mimic
typical experimental situations, we have identified an important constraint when
characterizing such networks: indications of a small-world topology can be expected solely
due to the spatial sampling of the system along with the commonly used time series analysis�…