Kognitive einschl. Biologische Psychologie, Institut für Psychologie, Universität Leipzig, Seeburgstr. 14-20, 04103 Leipzig, Germany.
Int J Psychophysiol. 2011 Aug;81(2):121-6. doi: 10.1016/j.ijpsycho.2011.05.001. Epub 2011 May 19.
The detection of an irregular, potentially relevant change (deviance) in the regular, unattended acoustic environment is ensured by the automatic deviance detection mechanism. It underlies the formation of a regularity representation and a comparison of an incoming sound with this representation. A mismatch outcome of this comparison evokes the mismatch negativity (MMN) of the event-related potential. For unattended pure tones the automatic deviance detection mechanism operates most efficiently for initial sound parts, which is why these are suggested to contribute more to sound representation than later parts. A transient that physically segments the sound can overcome this temporal constraint in sound representation. Whether the resulting individual (initial and terminal) sound segments or the joined two-segments give rise to the regularity representation is addressed here. We took advantage that the MMN attenuation to the second of two successive deviances (deviance-repetition effect) is more pronounced when the deviances belong to the same unit of representation. We measured MMN for two deviances (frequency modulations) within segmented sounds that either occurred within the initial or the terminal segment, or that were split across both segments. Unexpectedly, we did not obtain a deviance-repetition effect. Instead, we obtained a temporal distance effect: With increasing temporal distance from deviance-onset relative to segment-onset the MMN amplitude decreased. Furthermore, this effect did not depend on whether the deviance occurred in the initial or in the terminal segment. Thus, (for the current approach) we suggest that the regularity representation is based on the individual rather than joined segments.
自动偏差检测机制确保了对规则、未被注意的声环境中不规则、潜在相关变化（偏差）的检测。它是形成规则表示和将传入声音与该表示进行比较的基础。这种比较的不匹配结果会引起事件相关电位的失匹配负波（MMN）。对于未被注意的纯音，自动偏差检测机制对于初始声音部分的工作效率最高，这就是为什么这些部分被认为比后续部分更能为声音表示做出贡献的原因。物理上分割声音的瞬态可以克服这种声音表示的时间约束。这里讨论的是产生规则表示的是单个（初始和终端）声音部分还是连接的两个部分。我们利用了在两个连续偏差（偏差重复效应）中第二个偏差的 MMN 衰减更为明显的情况，当偏差属于同一表示单元时。我们测量了分段声音中两个偏差（频率调制）的 MMN，这些偏差要么发生在初始段内，要么发生在终端段内，要么跨越两个段。出乎意料的是，我们没有得到偏差重复效应。相反，我们得到了一个时间距离效应：相对于段开始，与偏差开始的时间距离越大，MMN 幅度越低。此外，这种效应不取决于偏差是发生在初始段还是终端段。因此，（对于当前的方法）我们建议，规则表示是基于单个而不是连接的部分。
