Time required for Judgements of Numerical Inequality

AN educated adult can tell which of two digits is the larger with virtually no uncertainty. By what process is this accomplished ? On the one hand, it is conceivable that such judgements are made in the same way as judgements of stimuli varying along physical continua. On the other hand, numerical judgements may be made at a different, less perceptual and more cognitive, level. For instance, the task may be one of memory access, each possible pair of numerals being stored with a corresponding inequality sign ; or perhaps some sort of digital computation is performed, such as counting the space between the two numerical values.