van Maanen, L., Grasman, R. P. P. P., Forstmann, B. U., Keuken, M. C., Brown, S. D., & Wagenmakers, E. J. (2012).
Similarity and number of alternatives in the random-dot motion paradigm. Attention, Perception &
Psychophysics, 74(4), 739-753. doi:10.3758/s13414-011-0267-7.