Relational timing has been proposed as a solution to the problem of variability across durational properties of speech arising with changes in speaking rate. The current study investigates the role of absolute and relational timing cues in perception of Japanese stop length (singleton/ geminate) categorization. Absolute (stop duration) and relational (ratio of stop duration to preceding mora duration) duration cues were independently varied in a categorization test. Although Ratio was shown previously to classify speakers’ productions more accurately (Idemaru, 2005), listeners’ category responses showed strong individual differences in cue use. These results demonstrate that a highly reliable acoustic cue in the distribution of cue available in speech production does not necessarily predict its primacy in speech perception.