Science builds on the achievements of the past. This chapter builds on previous psychophysical experiments that occur before the predictions of the current theory of mental decision making were known. No contamination of these previous results occurred due to knowledge of the current theoretical predictions. Experiments by Kellogg (1931) and Link (1971) generated results predicted by Link’s (1975, 1992) theory of comparative judgment. Both response time and proportions are related by new theoretical predictions. These predictions lead to a method for measuring the duration of a small time epoch within which comparisons are made to be accumulated into a response. The duration of this time epoch is about 5 ms.