Investigated the process of numeric comparison by asking 4 groups of 10 college students to judge which of 2 digits or which of 2 dot patterns was numerically larger. Stimuli were either digits or dot patterns in familiar, unfamiliar, or random configurations. Mean reaction time was systematically related to the difference between logarithms of the stimulus values. A single numeric comparison process gave good account of the data for all stimulus types. This process was well described by a random walk model with variable step size and fixed boundaries. Reaction time matrices were further analyzed using J. B. Kruskal's 1964 multidimensional scaling program MD-SCAL, and the recovered stimulus configurations were successfully simulated from a simple version of the model. (15 ref) (PsycINFO Database Record (c) 2006 APA, all rights reserved)