启动合成人脸的整体与局部加工:一项EEG研究

摘要

合成-人脸错觉指当加工合成人脸的上半部分时,下部分人脸由于人脸的整体加工优势而难以被忽略的现象.研究者采用合成-人脸错觉与Navon刺激发现,启动Navon刺激的整体或局部加工会影响人脸的整体加工,对理解人脸的加工机制起了重要作用.然而,该种影响的神经机制尚不明确.考虑到大脑左、右半球分别在加工局部与整体信息上存有优势,笔者预测Navon刺激启动是通过调节左、右半球的参与程度来影响对人脸的加工.本研究首次采用EEG技术,以枕区α节律为指标对该假设进行了检验.笔者重复以往行为研究结果,然而,无论对Navon刺激进行整体还是局部加工,α节律的能量总是右侧比左侧高,提示Navon刺激对人脸加工的影响并非通过改变大脑两半球的参与程度实现.%In prior research,it has been shown that,using the composite-face illusion and the Navon patterns,the global/local level processing of the Navon patterns influenced the holistic processing of faces within a trial.The composite-face illusion reflects the difficulty to ignore one half (e.g.,bottom) of a face when the two aligned halves are incongruent.However,the neural mechanism supporting this effect remains unknown.Since a functional hemisphere asymmetry exists for the global versus local processing,with the left hemisphere (LH) and right hemisphere (RH) tunes to the local and the global processing,respectively,we predicted that the priming effect might be related to the modulation of the relative involvement of the LH and the RH.Here in the present study,we tested this hypothesis by comparing the alpha band (8-12 Hz) activity in the EEG recorded at posterior right and posterior left hemisphere sites while participants processed the global/local level of Navon patterns.We found that the global versus local processing modulated the composite-face illusion,however,the alpha band activity exhibited significantly stronger activities in the RH than in the LH in both priming levels.These results imply that the priming effect is not due to the modulation of the relative involvement of the LH and the RH.