Arousal-Driven Serial Dependence: Internal States Modulate Perceived Duration

Emotional experience shapes not only how we perceive the present but also how the past influences our judgments. In this study, we examined how emotional arousal and valence modulate serial dependence in time perception—a phenomenon in which prior experiences bias current estimates. Using a duration reproduction task, participants viewed affective images drawn from the International Affective Picture System (IAPS) to induce high-arousal (positive or negative) or low-arousal (neutral) emotional states. We found that participants consistently overestimated durations in high-arousal conditions compared to those in low-arousal conditions, regardless of valence. Crucially, serial dependence effects were significantly amplified during high-arousal states. This effect was strongest when high-arousal trials were preceded by similar high-arousal trials, indicating a state-dependent intensification of sequential bias. Emotional valence, by contrast, had no significant effect on either temporal distortion or serial dependence. These findings suggest that emotional arousal, rather than valence, plays a key role in shaping the temporal integration of past and present, offering new insight into how affective states shape temporal cognition and serial dependence.