疼痛表情对秒下及秒上时距知觉的影响

采用二分法和泛化法范式，在秒下及秒上呈现时距探究疼痛表情对时距知觉的影响。结果发现，使用二分法，疼痛表情在秒上秒下都显著延长了个体的主观时距，但使用泛化法，疼痛表情仅在秒上产生影响。根据时间分段综合模型和范式特点，该实验结果反映疼痛表情对时距知觉的影响在秒上秒下的作用机制可能不同，在秒下主要是通过唤醒影响，在秒上则可能由唤醒和注意共同调节。

The Influence of Facial Expressions of Pain on Subsecond and Suprasecond

The aim of the current study was using a temporal generalization task and a temporal bisection task to explore whether facial pain could affect subsecond (200~800 ms) and suprasecond (1400- 2600 ms) time perception.Twenty six participants (fifteen males) participated in bisection task, which consisted of two blocks with different stimulus durations (200~800 ms vs. 1400~2600 ms), the order of them was counterbalanced across participants. In the block with 200~800 ms durations, the block consisted of a learning phase which used a “short” (200 ms) and a “long” (800 ms) anchor duration, a traing phase and a test phase involving seven probe durations (400, 600, 800, 1000, 1200, 1400 and 1600 ms). The participants were initially presented with the “short” and “long” anchor durations in the form of a light brown rectangle randomly. Then they were trained to press D/K keys to indicate whether the presentation duration of the rectangle was more closer to “short” or “long” anchor duration. A feedback was given after each response. In the test phase, participants were told that the rectangle would be replaced by faces and no feedback presented. Each participant completed 140 trials presented randomly. In another block, the material and the procedure were similar to 200~800 ms condition, except using 1400 ms and 2600ms as “short” and “long” standard duration and 1400,1600,1800,2000,2200,2400,2600 ms as comparison durations. To verify whether the effect of facial pain on time perception was stable. Other twenty six participants (nine males) took part in generalization task, which used a basically same procedure and materials as the time bisection task, without the standard durations was replaced to 500 ms in 200~800 ms condition and 2000 ms in 1400~2600 ms condition, as the demand was changed to judge whether the present duration was "same" or "different" to the standard duration.In temporal bisection task, the results pertaining to PSE revealed a significant main effect of duration , a significant main effect of facial expression, and a significant duration × face interaction, Subsequent Simple-effects Analysis showed that, in subsecond range, the PSE on facial pain was significantly lower than facial neutral, and in suprasecond range, the PSE on facial pain was also significantly lower than facial neutral. The analysis of WR just found a significant main effect of duration. The results tell a subjective lengthening effect produced by the perception of pain faces in both subsecond range and suprasecond range. In tempotal generalization task, the results pertaining to PSE revealed a significant main effect of duration and a significant main effect of facial expression, while the duration×face interaction was nonsignificant. A Paired Samples t-test showed that, in suprasecond range, the PSE on facial pain was significantly lower than facial neutral, while no significant difference was found between pain and neutral faces in subsecond range. The analysis of WR just found a significant main effect of duration. The results suggested a subjective lengthening effect produced by the perception of pain faces in suprasecond duration.It could be speculated that, in temporal bisection task, facial pain could accelerate the rate of the pacemaker because of its high arousal, and make the switch close quickly or open lately, or keep it at a relatively stable closed state, resulting a relatively long subjective duration. While in temporal generalization task, the effect of pain expression on temporal perception was just found in suprasecond range, it may because the arousal effect on timing was diminished as this task demands subjects remember the standard duration. Considering that different contribution of arousal and attention will change based on the time elapsed since the onset of the emotional event. These results suggest a major role of arousal mechanisms involving in subsecond time perception and both arousal and attention mechanisms in suprasecond time perception in the effect of facial pain expressions on time perception.