A. M. MacEachren and R. E. Roth and J. O'Brien and B. Li and D. Swingley and M. Gahegan.
Visual Semiotics & Uncertainty Visualization: An Empirical Study.
In IEEE Transactions on Visualization and Computer Graphics, vol. 18, no. 12, pp. 2496--2505, 2012.

Bibtex:

@Article{       maceachren:2012:VSUV,
  title =       {Visual Semiotics \& Uncertainty Visualization: An
                 Empirical Study},
  author =      {A. M. MacEachren and R. E. Roth and J. O'Brien and B.
                 Li and D. Swingley and M. Gahegan},
  journal =     {IEEE Transactions on Visualization and Computer
                 Graphics},
  volume =      {18},
  number =      {12},
  pages =       {2496--2505},
  year =        {2012},
}