空间-数字反应编码联合效应下冲突适应过程的ERP研究

Conflict Adaptation under the SNARC Effect:An ERP Study

为了考察被试在不能意识到任务中包含冲突的情况下的认知控制过程，将产生SNARC效应的奇偶判断任务看作是一种潜在的冲突任务。大小与反应手一致的视为一致的试次，大小与反应手不一致的视为不一致的试次。根据不一致试次之前一个试次的类型将其划分为iI（不一致-不一致，incongruent-incongruent）试次和cI（一致-不一致，congruent—incongruent）试次两种类型。对冲突适应过程的分析表明iI试次的反应时显著快于cI试次，iI试次和cI试次相比，两者的脑电在大约260～300ms的时间段内在FCz位置上差异最大。偶极子分析表明差异波的产生源定位于背侧前扣带回（dorsal anchor cinglate cortex），这些结果与前扣带回的意识监测理论并不一致。最后结合冲突监测理论和其他解释前扣带回功能的理论对研究结果做了相应的解释，认为冲突适应可以是一个无意识的过程。

The humatl anterior cingulate cortex （ACC）, which is active during many conflict - monitoring tasks, is believed to participate with the prefrontal cortex in a distributed network for conscious self - regulation. The hypothesis of this study predicts that conflict - related ACC activation will occur only when the conflicting stimuli are consciously perceived. Consistent with this view, Dehaene found that subliminal conflicts are resolved without ACC contribution under the subliminal conflict paradigm. Other studies have also found that the awareness of conflict is a precondition for conflict adaptation. However, other researchers have challenged this tight relation between awareness of conflict and conflict control. To clarify the relation between the awareness of conflict and conflict adaptation, we investigate conflict in the absence of consciousness by relying on the SNARC effect. Participants are probably not explicitly aware of conflict on the parity judgment task. In our study, the SNARC compatible trial is a congruent trial and the SNARC incompatible trial is an incongruent one. For the purposes of analysis, we divide the incongruent trials into two categories： those that follow compatible trials （labeled here as cI）, and those that follow incompatible ones （labeled here as iI）. High - density event - related potentials （ERPs） were recorded to examine the electrophysiological correlates of conflict adaptation. The stimuli consisted of the digits 1,2, 3, 4, 6, 7, 8, and 9. Each trial began with the presentation of an Arabic number; the number was presented for 300ms at the center of the screen, after which it disappeared. After a varied interval of 1200 - 1800ms, the next trial began. The study consisted of 640 trials, with the number of iI and cI trials being the same. The experiment consisted of two separate sessions in which the mapping of parity to the response side was varied. The results indicated that the interaction between magnitude and side of response was significant, suggesting a clear SNARC effect on RTs. The RTs for the cI trials were significantly slower than those for the iI trials, indicating a clear conflict adaptation effect. For stimulus - locked waveforms, the N2 showed peak differences - between the cI and iI conditions - to be maximal at Fcz in the 260 - 300ms interval after the target. No significant difference emerged between congruent and incongruent trials. A voltage map of the difference wave showed strong activity at the frontocentral region. The dipole analysis （BESA software） localized the generator of the difference wave （cI minus iI） in the dorsal ACC. The study found the conflict adaptation effect under the SNARC effect, which is inconsistent with the classic conscious monitoring view. Since there may be some debate on defining the parity judgment task as a conflict task, we are aware that caution needs to be exerted in drawing firm conclusions from our study, which adds to the ongoing debate of the role of the ACC in cognition.