The Effect of Emotion on Time Perception for Complex Visual Stimuli

Abstract

<p>Activation and attention have opposite effects on time perception. Emotion can both increase physiological activation (which leads to overestimation of time) and attract attention (which leads to underestimation of time). Although the effect of emotion on time perception has received a growing amount of attention, the use of different time estimation tasks and stimuli makes it difficult to compare findings across studies. The effect of emotion on the temporal perception of complex stimuli (e.g. scenes) is particularly under-researched. This thesis presents a systematic assessment of the effect of two key emotional dimensions, arousal and valence, on time perception for visual stimuli. Studies were designed to control for factors that may modulate emotion effects, such as image repetition and carry over from one emotion to another. The stimuli were complex images standardized for arousal (high or low) and valence (positive or negative) as well as neutral images. The first study compared three time estimation tasks to determine which were sensitive to emotion effects. The selected task, temporal bisection, was used to test time perception in three duration ranges: short (400 to 1600ms), middle (1000 to 4000ms), and long (2000 to 6000ms). Results of bisection point analyses revealed that the duration of attention-capturing stimuli (e.g. high arousal or negative images) was underestimated compared to that of other stimuli (e.g. low arousal or neutral images). These findings are at odds with activational effects of emotion (overestimation of emotional stimuli), which are typically found in studies of time perception for facial expression. Better temporal sensitivity in the long range than in short and middle ranges suggests that participants used different timing strategies to perform the bisection task at longer stimulus durations. To test the effect of emotion on time perception using a discrete rather than dimensional classification of emotion, experiments were replicated using emotional facial expressions as stimuli. Time estimates in the short and middle ranges did not show attentional effects, but pointed to activational effects of emotion. Facial expression had no impact on time perception in the long duration range. Taken together, these experiments show that the effect of emotion on time perception varies according to both duration and stimulus type. Emotional facial expressions have short lived activational effects whereby the duration of arousing stimuli is overestimated, whereas complex emotional scenes have protracted attentional effects through which the duration of attention-capturing stimuli is underestimated.</p>