In an experiment involving semantic search, the visual movements of sample
populations subjected to visual and aural input were tracked in a taskless
paradigm. The probability distributions of saccades and fixations were obtained
and analyzed. Scale-invariance was observed in the saccadic distributions,
while the fixation distributions revealed the presence of a characteristic
(attentional) time scale for literate subjects. A detailed analysis of our
results suggests that saccadic eye motions are an example of Levy, rather than
Brownian, dynamics.Comment: Accepted to Europhysics Letters (2011
