Comparisons of digits and dot patterns.

The process of numeric comparison was investigated. Four groups of 10 5s were asked to judge which of two digits or which of two 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 fur-ther analyzed using Kruskals 1964 multidimensional scaling program MD-SCAL, and the recovered stimulus configurations were successfully simulated from a simple version of the model. Moyer and Landauer (1967) presented two single digits simultaneously and asked 5s to respond as rapidly as possible to the digit that was numerically larger. Reaction