视时距知觉适应后效的空间选择性

时距知觉适应后效是指长时间适应于某一特定时距会导致个体对后续时距产生知觉偏差。其中对视时距知觉适应后效空间选择性的探讨存在争议,有研究支持位置不变性,也有研究支持位置特异性。这类研究能有效揭示时距编码的认知神经机制,位置不变性可能意味着时距编码位于较高级的脑区,而位置特异性则可能意味着时距编码位于初级视觉皮层。未来还可以探究时距知觉适应后效的视觉坐标表征方式,开展多通道研究以及相应的神经基础研究。

The spatial selectivity of the visual duration aftereffect

Duration aftereffect refers to prolonged adaptation to one duration biases the perception of the subsequent duration. For example, adapting to a relatively short duration, the subsequent stimulus of intermediate duration will be perceived longer, whereas adapting to a relatively long duration, the subsequent stimulus of intermediate duration will be perceived shorter. Previous studies yielded two different viewpoints about whether the visual duration aftereffect could transfer from one position to another position. On the one hand, some researchers suggest that the duration aftereffect could transfer to another position, in other words, the duration aftereffect is position invariance. On the other hand, some researchers argue that the duration aftereffect could not transfer to another position, that is, the duration aftereffect is position specificity. The discussion of the spatial selectivity of the visual duration aftereffect should help reveal the cognitive neural mechanism of duration perception better. Position invariance may suggest that the coding of duration is located in some higher cortex, whereas position specificity may suggest that the coding of duration is located in the primary visual cortex. Researches have showed that the neurons at early visual cortex are usually characterized by small receptive fields, which are often confined to the contralateral visual field. Therefore, if the duration adaptation occurs in the primary visual cortex, the duration aftereffect should be limited to the adaptive position or a few degrees away from the adaptive position, and it cannot transfer to another visual field. On the contrary, if duration adaptation occurs in higher cortex, the duration aftereffect can transfer to a position far from the adaptation position or another visual field. In the future, we can first explore the visual coordinate representation of the duration aftereffect. In the previous studies of duration aftereffect, the gaze points presented to the participants remained stable during the whole task. In our daily life, however, things such as rapid eye movements, rotation of the eyes and head, shaking of the body may all lead the change of our gaze points, which may lead to the change of the images projected on the retina. By manipulating the positions of the gaze points, future researches can explore whether the representation of the duration aftereffect is retinotopic or spatiotopic. Furthermore, it is also important to investigate the spatial selectivity of the duration aftereffect in other sensory modality. Our time perception is usually based on comprehensive information, such as visual, auditory and tactile information. The present studies mainly focus on visual modality, but few researchers examine the spatial selectivity of the duration aftereffect in auditory or tactile modality. The duration aftereffect were also shown in the auditory and tactile modality. Thus future studies are able to examine this effect of different spatial orientations and distances in different sensory modality. At last, we can investigate the neural mechanism underlying the spatial selectivity of the duration aftereffect using multiple indicators. For instance, ERP technology can be used to determine whether the aftereffect is position specific or position invariant by CNV components which evoked by adaptation, so as to further investigate the time course of the spatial selectivity of the duration aftereffect. Moreover, the fMRI adaptation technique can also be used to uncover the locus of neural adaptation, and whether these neurons is position invariant or position specific. Without specific sensory receptor, it is difficult to explore the cognitive neural mechanism of time. Duration aftereffect and its spatial selectivity, which have received increasing focus, provide a new perspective to bring it to light. This review summarizes the behavioral and neurophysiological evidence that support the different spatial selectivity of the duration aftereffect, tries to analyze the possible reasons of different research results, and proposes possible directions for future studies.