Time perception and the Stroop task.

Three experiments were conducted to assess the effects of the Stroop task (color-word incongruities) on observers' estimates of 30-sec. inspection periods. The experiments differed in psychophysical procedure; the three classic methods of production, reproduction, and verbal estimation were employed. Observers underestimated the passage of time, compared to doing nothing, when they were engaged on the Stroop task. However, judgments of duration on the Stroop task were shorter than those made in the control condition of naming color dots only when the method of production was employed. These findings are similar to results with mental arithmetic tasks and contribute to the understanding of the relationship between cognitive processing and time perception.