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首页> 外文期刊>Brain research >The effect of visual task difficulty and attentional direction on the detection of acoustic change as indexed by the Mismatch Negativity.
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The effect of visual task difficulty and attentional direction on the detection of acoustic change as indexed by the Mismatch Negativity.

机译：视觉任务难度和注意力方向对由不匹配负性指示的声学变化检测的影响。

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Naatanen's model of auditory processing purports that attention does not affect the MMN. The present study investigates this claim through two different manipulations. First, the effect of visual task difficulty on the passively elicited MMN is assessed. Second, the MMNs elicited by stimuli under attended and ignored conditions are compared. In Experiment 1, subjects were presented with mixed sequences of equiprobable auditory and visual stimuli. The auditory stimuli consisted of standard (80 dB SPL 1000 Hz), frequency deviant (1050 Hz), and intensity deviant (70 dB SPL) tone pips. In a first instance, subjects were instructed to ignore the auditory stimulation and engage in an easy and difficult visual discrimination task (focused condition). Subsequently, they were asked to attend to both modalities and detect visual and auditory deviant stimuli (divided condition). The results indicate that the passively elicited MMN to frequency and intensity deviants did not significantly vary with visual task difficulty, in spite of the fact that the easy and difficult tasks showed a wide variation in performance. The manipulation of the attentional direction (focused vs. divided conditions) did result in a significant effect on the MMN elicited by the intensity, but not frequency, deviant. The intensity MMN was larger at frontal sites when subjects' attention was directed to both modalities as compared to only the visual modality. The attentional effect on the MMN to the intensity deviants only may be due to the specific deviant feature or the poorer perceptual discriminability of this deviant from the standard. Experiment 2 was designed to address this issue. The methods of Experiment 2 were identical to those of Experiment 1 with the exception that the intensity deviant (60 dB SPL) was made to be more perceptible than the frequency deviant (1016 Hz) when compared to the standard stimulus (80 dB SPL 1000 Hz). The results of Experiment 2 also demonstrated that the passively elicited MMN was not affected by large variations in visual task difficulty; this provides convincing evidence that the MMN is independent of visual task demands. Similarly to Experiment 1, the direction of attention again had a significant effect on the MMN. In Experiment 2, however, the frequency MMN (and not the intensity MMN) was larger at frontal sites during divided attention compared to focused visual attention. The most parsimonious explanation of these results is that attention enhances the discriminability of the deviant from the standard background stimulation. As such, small acoustic changes would benefit from attention whereas the discriminability of larger changes may not be significantly enhanced.
机译：Naatanen的听觉处理模型声称注意力不会影响MMN。本研究通过两种不同的方法研究了这一主张。首先，评估了视觉任务难度对被动引发的MMN的影响。其次，比较了在有人照看和被忽略的情况下由刺激引起的MMN。在实验1中，向受试者呈现等概率的听觉和视觉刺激的混合序列。听觉刺激包括标准（80 dB SPL 1000 Hz），频率偏差（1050 Hz）和强度偏差（70 dB SPL）音调点。首先，指示受试者忽略听觉刺激，并进行容易和困难的视觉辨别任务（集中条件）。随后，要求他们参加两种检查方法，并检测视觉和听觉上的异常刺激（分裂状况）。结果表明，尽管容易完成的任务和执行困难的任务表现出很大的差异，但是被动地引发频率和强度偏差的MMN并不会随着视觉任务的困难而显着变化。注意方向的操作（集中条件与分开条件）的确对强度（而不是频率）异常引起的MMN产生了重大影响。与仅视觉方式相比，当受试者的注意力集中在两种方式时，额叶MMN的强度更大。 MMN对强度偏差的注意力影响可能仅是由于特定偏差特征或该偏差与标准之间较差的可感知性。实验2旨在解决此问题。实验2的方法与实验1的方法相同，除了与标准刺激（80 dB SPL 1000 Hz）相比，强度偏差（60 dB SPL）比频率偏差（1016 Hz）更明显。 ）。实验2的结果还表明，被动激发的MMN不受视觉任务难度大变化的影响。这提供了令人信服的证据，表明MMN与视觉任务需求无关。与实验1相似，注意力的方向再次对MMN产生了重大影响。然而，在实验2中，与集中的视觉注意力相比，在分散注意力期间额叶部位的频率MMN（而非强度MMN）更大。这些结果最简约的解释是，注意力增强了偏离标准背景刺激的能力。这样，较小的声学变化将受到关注，而较大变化的可辨别性可能不会得到明显增强。

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