工作记忆中注意焦点转换的代偿机制——来自聋生和发音抑制的证据

The Compensatory Mechanism of Focus of Attention Switch in Working Memory:The Experimental Evidence from Deaf Students and Articulatory Suppression

注意焦点转换是工作记忆中一项重要的执行功能。前人的研究提示视空间画板可能参与言语工作记忆中的注意转换。通过聋生和发音抑制方式探索语音回路子系统受损或受阻后,视空间画板子系统完成注意转换任务的反应模式。采用"三计数"任务,实验一比较了极重度耳聋学生和健听学生在工作记忆中的注意焦点转换效应。结果表明聋生与健听被试在不同记忆子项中转换的反应时间均长于不转换时间。但与健听被试相比,聋生完成注意转换任务的正确率降低,在转换和不转换之间的反应时差别减小,且转换方向对反应时无影响,转换方向和转换距离表现出显著的交互作用。下行转换时近转换快于远转换,上行转换时近转换慢于远转换。实验二比较了发音抑制和无抑制条件下的注意转换效应,发音抑制组在注意焦点转换中表现出与聋生组既类似又存在区别的反应模式。这些结果提示工作记忆的中枢执行系统具有高度的灵活性。当语音回路功能受阻后,注意转换仍能借助视空间画板子系统得以完成。与暂时性抑制相比,语音回路功能长期受损后表现出一定的功能代偿。

Focus of Attention（FOA） switch is one of fundamental executive functions in working memory.Previous results suggested that the visual-spatial sketch pad was recruited in attention switch of verbal working memory.In the present study,we examined the behavioral patterns of attention switch with the visual-spatial sketch pad when the phonological loop was suppressed by deaf students and articulatory suppression.By using ＂tri-count＂ task,we compared the performance of FOA switch between deaf students and hearing students（Experiment 1）.The result showed the RT of FOA switch was longer than that of no switch both in the two groups.Compared with hearing students,the accuracy of switch task was lower;and the RT difference between switch and no-switch was shorter in deaf students.In addition,switch direction did not affect RT,but a significant interaction between switch direction and distance was found in deaf students.The RT of close switch is faster than that of far switch in downward switch,but the RT of close switch is slower than that of far switch in upward switch.We further compared the performance of attention switch between articulatory suppression group and no suppression group（Experiment 2）.A similar but subtle different pattern was found between articulatory suppression group and deaf students.The current result suggested the central executive of working memory shows high flexibility.The FOA switch with the visual-spatial sketchpad can exhibit different pattern when the phonological loop has been suppressed.Comparing with the condition of the temporal suppression,functional compensation is observed in permanent suppression.