Figure 5. The group mean probability of responding ‘‘shorter’’ and standard error of the mean are plotted for each S2 duration in Experiment 4. doi:10.1371/journal.pone.0021829.g005 time, participants should produce longer durations when primed with an emotional as compared to a neutral image. If, however, emotions distract from the monitoring of time when dissociated from the timing signal, then participants should produce shorter durations when primed with an emotional as compared to a neutral image. Experiment 5 Method Participants. Eighteen female college students participated in the present study in fulfillment of an introductory psychology course requirement. The data of four participants was discarded because they were unable to accurately discriminate the durations presented for reproduction. The mean age of the remaining participants was 22.4 years (SD = 1.86). They were all right- handed [39] and reported normal or corrected to normal vision. Procedures. A trial started with the presentation of a fixation cross, which remained on screen for 500 ms. The cross was followed by a picture presentation for 800 ms. After a short empty interval of 500 ms, a circle appeared on the screen for 1100, 1700 or 2300 ms. After a longer empty interval of 5500 ms, a 500 ms cross prompted participants to attend to the onset of another circle. Participants were asked to push a button when they thought the duration of the second circle matched that of the first circle. Inter-trial intervals were equally distributed among 1800, 2100, and 2400 ms. The visual stimuli used here were comparable to those of Experiment 1. On half the trials, a timing stimulus was preceded by an emotionally negative picture, whereas on the remaining Emotion Effects on Timing trials it was preceded by a neutral picture. There were a total of 30 emotional and 30 neutral trials with one third each for the 1100, 1700 and 2300 ms duration conditions. Trials were presented in random order. Results We computed mean reaction times and standard deviations for each participant across all experimental conditions and removed trials from the analysis in which participants deviated more than two standard deviations from their respective mean. Using the remaining trials, we then computed means for each participant and condition and subjected those to an ANOVA with Emotion (negative, neutral) and Duration (1100, 1700, 2300) as repeated measures factors. This analysis revealed an Emotion main effect 2 (F(1, 13) = 11.23, p,.01, g partial = 0.46) indicating that partici- pants reproduced shorter durations when the timing signal was preceded by an emotional as compared to a neutral image. The Duration effect was also significant (F(2, 26) = 226.32, p,.0001, 2 g partial = 0.94) indicating that participants temporal reproductions were shortest for the 1100 ms condition, intermediate for the 1700 ms condition and longest for the 2300 ms condition (Figure 6). The interaction of Emotion and Duration was non- significant (p..1). Discussion The subjective shortening of duration when the timing stimulus was preceded by an emotional stimulus in the reproduction paradigm of Experiment 5 confirms that the results of Experiments Figure 6. The group mean response time and standard error of the mean are plotted for each target duration in Experiment 5. doi:10.1371/journal.pone.0021829.g006 PLoS ONE | www.plosone.org 6 July 2011 | Volume 6 | Issue 7 | e21829