倾斜错觉现象，指的是定向环绕的外周光栅刺激会让人们对同时呈现的中心光栅刺激的朝向感知产生偏差，在实际实验中，个体差异使得人们对于同一个倾斜错觉刺激的反应不同，即倾斜错觉刺激诱发的错觉大小存在个体差异。倾斜错觉现象可能与神经元层面的外周调制有关，然而，由于很难判断实验动物的心理感知，倾斜错觉和电生理中记录的外周调制的关系一直是未被研究的问题。

    我们将使用脑电这种非侵入性的、适用于人类被试的脑信号采集方式收集电生理数据，并结合行为学实验的结果探究倾斜错觉和外周调制的关系。首先我们固定中心刺激以20hz频率闪烁，通过有无外周刺激两种条件下引发的稳态视觉诱发电位的差异计算外周调制的强度；此外，采集同一个被试受外周朝向影响的倾斜错觉的感知情况；最后计算外周调制和倾斜错觉的相关性。

    本研究利用稳态视觉诱发电位范式与倾斜错觉范式探究受朝向影响的外周调制现象。利用64通道脑电记录系统，共记录了21位人类被试的行为结果，其中14位被试同时采集了脑电信号。从行为结果可以看出，尽管倾斜错觉的程度在个体间存在一定的差异，总体平均结果表明我们对中心刺激的朝向感知会受到外周刺激朝向的影响；电生理结果表明，引入外周刺激后会影响中心刺激诱发的脑电强度，在枕叶这种外周调制以抑制为主。最后通过相关分析，我们发现枕叶区域的EEG抑制作用与倾斜错觉的感知程度之间呈现显著的正相关，表明枕叶区域的外周调制可能是形成倾斜错觉这种感知效应的基础。

    Tilt-illusion refers to that the directional surround contextual grating stimuli bias the orientation perception of simultaneously presented central grating stimuli. In actual experiments, individual differences make people respond differently to the same tilt-illusion stimulus, i.e., there are individual differences in the magnitude of illusions induced by tilt-illusion stimuli.Tilt illusion may be related to contextual modulation at the neuronal level. However, because it is difficult to judge the psychological perception of experimental animals, the relationship between tilt illusion and contextual modulation recorded in electrophysiology has not been studied.

    We will use EEG, a non-invasive brain signal acquisition method suitable for human subjects, to collect electrophysiological data, and explore the relationship between tilt illusion and contextual modulation in combination with the results of behavioral experiments. Firstly, we calculated the intensity of contextual modulation by the difference of steady-state visual evoked potentials induced by fixed central stimulation at the frequency of 20 Hz; In addition, the perception of the tilt illusion affected by the surround orientation of the same subject was collected; Finally, the correlation between contextual modulation and tilt illusion was calculated.

    In this study, steady-state visual evoked potential paradigm and tilt illusion paradigm were used to explore the phenomenon of contextual modulation affected by orientation. The behavioral results of 21 human subjects were recorded by 64 channel EEG recording system, of which 14 subjects collected EEG signals at the same time. From the behavioral results, we can see that although the degree of tilt illusion varies among individuals, the overall average results show that our perception of the orientation of central stimuli is affected by the orientation of surround stimuli; Electrophysiological results showed that the introduction of surround stimulation would affect the EEG intensity induced by central stimulation, and this contextual modulation was mainly inhibition in the occipital lobe. Finally, through correlation analysis, we found that there was a significant positive correlation between EEG inhibition in the occipital region and the perception degree of tilt illusion, indicating that the contextual modulation in the occipital region may be the basis of the perception effect of tilt illusion.