摘要: 个体当前的知觉反应不仅取决于当前的刺激输入，而且依赖于先前的感知经验，可表现为知觉的序列依赖效应。结合时距二分任务，通过三个实验系统改变先前试次和当前试次中刺激的位置关系，考察了时距知觉的序列依赖效应及其空间迁移性。结果发现，（1）先前试次的刺激时距导致了排斥性的刺激序列依赖效应，并且这种效应能够完全迁移到不同的空间位置；（2）先前试次的决策反应导致了吸引性的决策序列依赖效应，但该效应仅能部分迁移到不同的空间位置；（3）时距知觉的刺激和决策序列依赖效应的空间迁移性不受空间类型（外部空间 vs. 视网膜空间）的调节。这些结果在一定程度上反映了视觉时距知觉序列依赖效应产生的潜在神经位置：刺激序列依赖效应可能产生于对空间信息不敏感或具有较大感受野的较高级视觉加工脑区；决策序列依赖效应则可能源于具有类别组织功能的高级认知脑区。
Abstract: To establish a stable and sensitive experience of the world, the brain tends to use recent history when forming perceptual decisions. This results in serial dependence in perception, by which previous trials affect the current perception. The serial dependence effect can be divided into (at least) two categories: the effect of previous stimuli (i.e., the stimulus serial dependence effect) and the effect of previous decisions (i.e., the decisional serial dependence effect) on the current perception. Although separate stimulus and decisional serial dependence effects have been demonstrated in duration perception, their spatial selectivity is unclear. In the present study, we investigated whether and how serial dependence in duration perception generalizes across different visual positions of stimuli.
The modified temporal bisection task was used in three experiments. Specifically, 24 naïve volunteers participated in Experiment 1. During the experiment, the visual stimulus (a white Gaussian blob) was pseudorandomly presented in the central or peripheral (10° from the left fixation) visual field. Participants were asked to judge whether the duration of the test stimulus (i.e., 300, 395, 520, 684, or 900 ms) was shorter or longer than a reference stimulus of intermediate duration (i.e., 520 ms) once the test stimulus disappeared. A group of 23 new volunteers were recruited for Experiment 2. The task of Experiment 2 was similar to that of Experiment 1, except that the visual stimulus was pseudorandomly located at either 5° to the left or 5° to the right of the central fixation. A new set of 24 volunteers participated in Experiment 3, in which the positions of both the fixation and the visual stimulus were changed; there were thus four types of positional relationships between stimuli across trials (i.e., identity, retinal position change, external position change, and both changes).
The results showed that previous stimulus duration and previous choice exerted opposing effects on serial dependence of duration perception: specifically, a repulsive stimulus serial dependence and an attractive decisional serial dependence. In other words, current duration estimates were repelled away from the previous trial’s stimulus duration but attracted toward the previous choice. We found these effects in both the central and peripheral visual fields. More importantly, we found that the stimulus serial dependence effect was not constrained by the visual position of the stimuli: the effects were comparable between contexts in which the stimulus positions of previous and current trials were the same and when they were different. The effects fully transferred across the central and peripheral visual fields, across the left and right visual hemifields, and across different external spaces. However, we found that the decisional serial dependence effect was larger in the position-consistent context than in the position-inconsistent context. This indicates that the decisional serial dependence effect could only be partially transferred across different visual positions regardless of the types of positions (i.e., spatiotopic vs. retinotopic).
These results provide evidence that both previous stimuli duration and previous choices affect subsequent perceptual decisions about duration, resulting in repulsive and attractive serial dependence effects, respectively. The repulsive stimulus serial dependence effect fully generalizes across different visual positions, suggesting it occurs primarily in higher-level visual areas. This also implies the existence of fast-duration adaptation. The attractive decisional serial dependence effect suggests that there is decision inertia in perceptual choices. Moreover, this effect is partly contingent on the visual position, which may result from the category organization function of higher-order brain areas. This suggests that the brain takes advantage of the visual position context when forming the decisional prior. These findings are helpful for understanding the plasticity of duration perception.