Sussman Elyse, Winkler István, Wang Wenjung
Department of Neuroscience, Albert Einstein College of Medicine, New York, New York 10461, USA.
Psychophysiology. 2003 May;40(3):430-5. doi: 10.1111/1469-8986.00045.
We addressed the question of whether the mismatch negativity (MMN) event-related potential reflects an attention-independent process. Previous studies have shown that the MMN response to intensity deviation was significantly reduced or even abolished when attention was highly focused on a concurrent sound channel, whereas no conclusive evidence of attentional sensitivity has been obtained for frequency deviation. We tested a new hypothesis suggesting that competition between detection of identical deviations in attended and unattended channels and the biasing of this competition induced by the subject's task account for the observed MMN effects. In a fast-paced dichotic paradigm, we set up competition for frequency MMN and removed it for intensity MMN. We found that frequency MMN was now abolished in the unattended channel, whereas the amplitude of the intensity MMN was unaffected. These results support the competition hypothesis and suggest that selective attention in and of itself does not affect the MMN. Top-down processes can determine what information reaches the deviance-detection process when changes in multiple channels vie for the same MMN resource and one of the competing changes is relevant for the subject's task.
我们探讨了失匹配负波（MMN）事件相关电位是否反映了一个与注意力无关的过程这一问题。先前的研究表明，当注意力高度集中在一个同时出现的声音通道上时，对强度偏差的MMN反应会显著降低甚至消失，而对于频率偏差，尚未获得注意力敏感性的确凿证据。我们测试了一个新的假设，即在所关注和未关注通道中相同偏差检测之间的竞争以及由受试者任务引起的这种竞争的偏向，解释了观察到的MMN效应。在一个快节奏的双耳分听范式中，我们为频率MMN设置了竞争，而消除了强度MMN的竞争。我们发现，现在未关注通道中的频率MMN消失了，而强度MMN的幅度未受影响。这些结果支持了竞争假设，并表明选择性注意本身并不影响MMN。当多个通道的变化争夺相同的MMN资源且其中一个竞争变化与受试者的任务相关时，自上而下的过程可以决定哪些信息进入偏差检测过程。
