Effect of tactile stimulus frequency on time perception: the role of working memory.

In most models of interval timing, there is a central clock, which is considered to be highly protected from the effects of external stimuli. However, many studies have reported such effects and different theories are proposed to explain the observations. These include the effect of arousal, attention sharing, memory load and information processing on central clock as well as change in the speed of the pacemaker. In this study, we used regular vibrotactile stimuli with different frequencies in a "duration reproduction task" to investigate the effect of stimulus content on interval timing. Results showed that subjects overestimated the duration as a function of test stimulus frequency. A significant correlation between increasing the test frequency and overestimation of subjective time was observed. We further investigated the effect of blank and filled gaps with various durations on time estimation. Analysis revealed that regardless of gap duration, subjective time increased in the filled gap condition, compared to the blank gap. This effect was independent from contextual stimuli and correlated to the mean number of stimuli during the temporal interval rather than rate of stimulus presentation.