中国科学院心理研究所机构知识库

本实验研究采用“跨通路延迟反应”实验模式，以提高非注意纯度，研究正常青年人非言语和言语两个系列的跨通路选择性注意事件相关电位但R.P)成分，以相减技术得到的偏差相关成分和注意成分为主要分析对象.对于注意ER.P研究中主要争论的焦点问题，为澄清其中的某些观点提供了进一步的证据，并对上述问题提出了一些新的见解.
主要结果与结论如下:①记录的非语言ERP成分与经典的Oddball模式的ERP成分性质基本相同，例如无论注意与否或何种刺激，最大N1均分布于额部;在语言ERP成分中，听觉N1最大峰位于额中央部，而视觉N1最大峰位于两侧枕部与颖后部，具有明显的通路差异性，因此N1可能是反映汉字形音初步加工的特异性指标.②在非语言听觉标准刺激、视觉标准与偏差刺激下，均在额部发现了注意N1波幅的增大;在语言实验中，听觉偏差刺激在额中央部，听觉标准刺激、视觉标准与偏差刺激在枕部与颖后部也发现注意N1显著增大.表明语言和非语言的注意加工均引起N1的选择性增大.针对N1是外源性成分还是混合性成分的争论，本研究认为N1是内、外源性成分重叠的结果.③在注意和较为严格的非注意条件下，观察到一个汉字形音产生的早期偏差相关负波(DRN 1)，除在非注意时的DRN1头皮分布与失匹配负波(MMN)不同外，其它峰潜伏期、波幅分布和注意效应等性质与MMN基本相同.并且，在视觉通路也证实了语言与非语言刺激的DRN1的上述特征均与听觉MIvI}I基本一致.据此，关于是否存在语言MIVII}I和视觉MMN的疑义，本实验结果可以初步认定语言MMN  和视觉MMN的存在.④比较注意与非注意的MMN平均波幅，结果听觉与视觉MIvirI波幅均不受注意的影响，汉字形音识别产生的DRNI，其波幅也不受注意的影响.针对MMN是否受注意的影响这一长期争论，本研究认为MMN波幅不受注意的影响，它是反映对语言和非语言刺激自动加工的重要指标.⑤非语言的早期注意成分(Ndl)的起始时间与注意N1相同，而早于非注意N1，表明在外源性成分起始前就发生了注意效应.在汉字形音加工的时间发生顺序上，依次为纯注意的Ndl、.混合成分的注意N1和纯外源性的非注意N1.针对注意的早期还是晚期选择这一注意理论的基本问题，本实验结果表明语言和非语言的注意效应均出现在外源性成分之前，提供了支持注意早期选择理论的进一步证据.⑥非语言听觉与视觉偏差刺激产生的Ndl最大峰分布于它们各自的初级感觉投射区，听觉与视觉标准刺激诱发的Ndl最大峰均分布在额部;语言听觉偏差刺激产生的Ndl最大峰位于额中央部，视觉偏差刺激产生的Ndl最大峰位于枕部;非语言听觉与视觉标准刺激诱发的Ndl最大峰均位于枕部。针对刺激的加工部位是通路特异性还是通路上机制的争论，本研究认为跨通路选择性注意对非语言偏差刺激的加工部位是通路特异性的，对语言偏差刺激的加工部位具有通路间差异性;而对非语言标准刺激的加工部位是通路上的，对语言标准刺激的加工部位具有通路间共同性.对于注意的选择性发生时程的早晚可因刺激条件而异、具有可塑性这一新见解，本实验提供了支持它的证据.8针对语言加工中N400与N200关系问题，本实验根据N350的峰潜伏期、波幅及其头皮分布特点，认为注意条件下的N350很可能是N200与N400的重叠，并主要表现出N400的特点;而非注意条件下，N35。则可能主要是N200。N35。的属性因条件而异，体现了ERP成分反映的大脑加工机制的可塑性。

Event-related potentials (ERPs) were measured in normal young subjects using the paradigm "Cross-modal and delayed response", which is able to improve inattention purity and to avoid the effect of task target on the deviance-related components (DRC) of ERPs.  The experiment was conducted under two conditions: one is attending to the visual modality but ignoring the auditory modality, the other is attending to the auditory modality but ignoring the visual modality.  A series of five kinds of stimuli were presented to every subject: standard, deviant stimuli and response imperative signal in attended channel; standard and deviant stimuli in unattended channel.  The visual and auditory stimuli including verbal and non-verbal stimuli presented in a pseudo-random order.  The presentation probability of standard stimuli was 82.5% and deviant stimuli was 17.5%.  Every standard or deviant stimulus was followed by a response imperative signal in attended modality.  The DRC was obtained by subtracting the ERPs of the standard stimuli from that of the deviant stimuli.  The attention components were obtained respectively by subtracting the ERPs of the standard and deviant stimuli in the unattended condition from those of the same standard and deviant stimuli in attended conditions.  To clarify present Standpoints that are the central issues of the ERPs research on selective attention，this experiment provided the further evidences and put forward some new ideas.
The main results and conclusions obtained in the present experiment are as follows:
1. The nature of E1ZPs components elicited by the non-verbal stimuli was identical with that found in classical oddball paradigms.  For example, the Nl was distributed at the frontal scalp regardless of modality or attention condition.  However, the largest Nl peak elicited by spoken words was located at the fronto-central scalp and the Nl elicited y the written words was located at lateral occipital and posterior-temporal area regardless of modality or attention condition.  This showed an obvious modality difference and suggested that the Nl elicited by verbal is probably specific index reflecting primary processing of Chinese shape and sound.
2. The Nl elicited using the non-verbal auditory standard, visual standard, and the deviant stimuli at the frontal area is increased under the attention condition than under the unattended condition. Under the verbal attending condition, the Nl yielded by the auditory deviant stimuli was increased at the fronto-central area and thatb by the visual standard, furthermore, the deviant stimuli was increased at the occipital and posterior-temporal areas.  This showed that the Nl selective enhancement caused by both verbal and non-verbal attention processing.  The present results suggest that the Nl is the outcome of overlapping with the endogenous and exogenous components in view of the dispute whether the Nl is of exogenous or mixed components.
3. Under both attended and strict unattended conditions, an early deviance-related (DRNI) was evoked by using Chinese orthographic and phonological processing.  The basic such as peak latency, distribution and attention effects were analogous with the mismatch negativity properties, (MIvIN) except for scalp distribution of DRN1 peak evoked under the unattended condition.  In addition, these properties of DRN1 yielded by visual verbal and non-verbal stimuli were also proved as same as auditory MIvIN.  Regarding the question as to whether or not visual MIvIN and verbal IvffVtN exists, it can be initially believed that the MIvIN exists in the visual modality and in the language processing process in the current experiment.
4. The auditory and visual MIvIN amplitudes were unaffected by attention while comparing them under attended with unattended condition,  The DRN1 amplitudes evoked by verbal were unaffected by attention.  The present research suggests that the MIvf1}I amplitude is independent of attention, therefore, it can be looked at as an important index of the reflection of automatic processing process of verbal and non-verbal stimuli in connection with a lasting debate about whether the MNIN is affected by attention.
5. The onset time of early attentive components (Ndl) elicited by non-verbal stimuli was the same as that of N 1如elded under the attention condition but was earlier than that of N1孙elded under the unattended condition.  The time sequence of the Chinese orthographic and phonological processing is as follows: the Ndl of relatively pure attention components, the attention N1 of combined with endogenous and exogenous components, and unattention N1 of relatively pure exogenous component. To counter the basic problem of the early or late selection, the present experimental results show that both verbal and non-verbal attention effects first occur before the exogenous components and this provides evidence supporting early selective theory.
6. In the non-verbal task, the largest Ndl elicited by auditory and visual deviant stimuli wasdistributed respectively over their primary sensory projection area, but Ndl evoked by auditory and visual standard stimuli was over the frontal scalp.  In the verbal task, the largest Ndl yielded by auditory deviant stimuli were located at the fronto-central area and visual ones were located at the occipital area, however, the Ndl elicited by auditory and visual standard stimuli were located over the occipital area. This suggests that the processing location of cross-modal attention to deviant stimuli is modality-specificity, while standard stimuli use a supramodal mechanism for non-verbal task. In the verbal task, the processing location of selective attention for deviants is different, however, for standards, it is common between modalities.  The present research suggests that early- and late- selection probably depends on various conditions for the selective attention, this has been debated for a long time.  This means the early-and late-selection of attention has plasticity.
7. According to the characteristics of N350 peak latencies, amplitudes and its scalp distribution, the current results suggest that the N350 is overlapping of N200 and N400, but N400 plays a more important role under the attended condition.  On the other hand, the N350 consists mainly of the N200 component under the unattended condition.  They are not immutable and this gives an expression that ERPs components reflecting a plasticity of the processing mechanism in the brain.