中国科学院心理研究所机构知识库

本实验的目的是:为“听觉失匹配负波(LIMN)是否受注意的影响”以及“视觉道有没有 MMN"这两个存在争论的问题提供进一步的实验证据。视觉刺激为呈现在屏幕中央的三种图形，一半实验中是红圆、红方和蓝圆，另一半实验中是蓝圆、蓝方和红圆，概率均分别为0.10, 0.10和0.80。听觉刺激用耳机呈现，标准刺激为55dB, 1000Hz之短声，偏差刺激仅在频率上与标准刺激不同，为1000Hz。视觉和听觉刺激同时呈现和消失，持续时间为20ms。刺激间隔(ISI)为700ms到 1300ms随机，变化间隔为50ms 实验分为三项:(1)注意听觉道，对其标准刺激和偏差刺激分别以左右手按键反应，同时保持眼睛注视屏幕中央;（2)注意视觉道，对颜色不同的图形分别以左右手反应(视觉单因素任务);(3)注意视觉道，对图形的颜色和形状之复合属性的不同分别以左右手反应(视觉双因素任务)。任务(3)和(2)的区别是任务难度不同。视觉和听觉道在注意和非注意下的偏差相关成分是分别通过偏差刺激的PRPs减去标准刺激的ERPs而得到的。结果发现，注意与非往意下听觉偏差刺激均引起了40-80ms的负波(分布在前额区)以及140-260ms间的负波(分布在前额一中央区)。其中40-80ms的负波不受注意的影响，可能反映了知觉初期额叶的作用 140-260ms间的负波则与MMN相似，在注意和非注意下都出现了，并且不受视觉任务难度的影响。视觉偏差刺激在注意条件下引起了N2区域ERP的增大;在非注意条件下，视觉道的颜色偏差刺激引起了Oz上180-220ms时程的负波，形状偏差刺激引起了80-200ms之间的负波(Oz点为峰潜伏期为124 ms和212 ms的两个负波)。所以本实验结果支持了“MMN 不受注意影响”的观点，并且提示:视觉道对于颜色和形状的改变可能存在自动的失匹配加工。

The purpose of this experiment was to provide further evidences for the two enduring questions，in which the first is” whether auditory mismatch negativity (MMN) is modulated by attention” and the second, "is there mismatch negativity in visual modality". Three kinds of figures presented on the centre of the screen were used as visual stimuli. In half of the blocks they were red circles, red squares and blue circles while in other blocks, blue circles, blue squares and red circles separately, both with the probability of 0.10, 0.10 and 0.80 . Auditory stimuli，in which standards were tones with density of 55dB and pitch of 800Hz，while deviants had 0.80. Auditory ne difference from the standards in pitch (1000Hz)，were presented to the two ears through earphone. Visual and auditory stimulus in each trial was presented simultaneously with the duration of 20 ms .The interstimulus interval (ISI) was varied randomly from i00ms to 1300ms per 50ms-The subjects were instructed to response to. (1) auditory standards and deviants，with dyes fixed on the centre of the screen; (2) figures with different color; (3) figures with different color and shape. The task difficulty was not the same between Task (3) and task (2). The deviant-related components of visual and auditory modality in attended or unattended conditions were separately obtained by subtracting the ERFs elicited by the standards from that of the deviants. The results show that，whether attended or not，two negative components were elicited by auditory deviants. The first frontally distributed negative component with the time window of 40-80ms was interpreted as reflecting the roles of frontal lobe in the early stage of information processing，while the second central-frontally distributed negative component was MMN-like because it didn't affected by visual task difficulty. Visual deviants enhanced N2 wave when they were attended but while unattended、a occipitally distributed neaativ0e component in 180-220ms time windows were elicited by both color-deviant and shape-deviant stimuli. Therefore, the results support that M?I-}IN is not modulated by attention, and imply that there are somewhat automatic mismatch processing to the attributes of visual stimuli. at least to color and shape.