Previous research has demonstrated that intuitive judgments of timeloss are often biased: overestimated when a high speed is slowed down and underestimated when a low speed is decreased further. Yet, no findings provide cognitive explanations of the bias. The present study (a) collected numerical judgments of time-loss by assigning participants to seven speed matching problems, and (b) collected verbal protocols of participants judgment processes. To identify different decision rules on the individual level, a spectral analysis of judgments was used. The findings show that the ratio rule was most frequently used and similar to the well researched time-saving bias, a ratio heuristic and a difference heuristic could model a majority of the timeloss bias. The validity of the method is supported by a significant correspondence between the spectral analysis measure and the qualitative analysis for consistent participants. By including affect as a third variable, future research could get a closer understanding of the bias effect in real life and consequently develop strategies that can improve road safety.