Perceptual complexity, rather than valence or arousal accounts for distracter-induced overproductions of temporal durations.

For humans and other species, the ability to estimate the physical passage of time is of fundamental importance for perceptual, cognitive or motor functions. Despite this importance, any subjective estimation of temporal durations not only depends on the temporal dynamics of the to-be-timed stimulus or event, but also can be distorted by non-temporal perceptual, cognitive, and emotional effects. This study aimed to further explore critical stimulus characteristics modulating distracter-induced distortions in human time-reproduction. To this end, we investigated whether subjectively rated distracter dimensions of arousal and valence (related to levels of emotionality), or rather stimulus complexity, as a confounder, produce distortions in participants' reproduction of a previously trained target interval. Accuracy and precision of time-reproduction have been measured in distracter-trials, and compared to timing performance in baseline-trials without any distraction. Results showed temporal overproductions in a magnitude of less than distracter duration only for complex distracters. Most importantly, arousal level and valence of distracters were not accountable for temporal distortions. Within an internal clock framework, our pattern of results can best be interpreted in the context of attention-, rather than arousal-based mechanisms of timing.