Objective To explore the representation of information in foveal vision split at the midline between the two hemispheres or bilaterally represented by overlapping projections of the fovea in each hemisphere.Methods The experiment adopts lexical decision task.Pictophonetic characters (pseudowords) are presented to the left or right of fixation, either close to fixation entirely within foveal vision (<1°), or further from fixation entirely within extrafoveal vision (>3°).Eye movements were recorded with an eye tracking device, which monitored participants' fixation location.Results ① A left visual field condition (LVF)/right hemisphere (RH) advantage effect is found for phonetic-semantic characters (PS) and semantic-phonetic characters (SP) in foveal vision and extrafoveal vision.Pictophonetic characters presented to the left side of fixation are recognized more quickly and accurately.② As the eccentric angles of fixation increasing, the LVF/RH advantage effect of PS characters does not disappear.③ Under the right visual field condition (RVF), the processing in SP characters recognition is superior to that in PS characters recognition.The error rates of PS characters are lower than SP characters in the LVF.Conclusion The findings indicate a precise split at the vertical midline of each fovea, where all visual information from the left or right of fixation is separately projected to the contralateral hemisphere.Furthermore, the position of phonetic components may influence how written pictophonetic characters are processed in the hemisphere.%目的 探讨中央凹视野区信息表征的方式是同时相等双侧投射两半球还是分割交叉投射对侧半球.方法 本研究将形声字真字与假字快速呈现在注视点左侧或右侧中央凹视野区(<1°)和旁中央凹视野区(>3°)范围,采用词汇判断任务并用眼动仪精确监控被试注视点位置.结果 ① 呈现于中央凹视野区和旁中央视野区范围注视点左侧声旁在左(phonetic-semantic, PS)、在右(semantic-phonetic, SP)形声字,其辨认速度和准确性比呈现于注视点右侧的形声字更快、更准确,表现出正字法加工的左视野/右半球优势效应.② 相比于SP形声字,PS形声字左视野/右半球优势效应未随离心视角增加而消失.③ 呈现于右视野区的SP形声字反应快于PS形声字,而左视野区PS形声字的错误率低于SP形声字.结论 中央凹视野区视觉信息的表征为沿垂直中线分割交叉投射到对侧半球,声旁位置影响大脑半球对形声字的加工.
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