Abstract
Acoustic environmental noise, even of low to moderate intensity, is known to adversely affect information processing in animals and humans via attention mechanisms. In particular, facilitation and inhibition of information processing are basic functions of selective attention. Such mechanisms can be investigated by analyzing brain potentials under conditions of externally directed attention (intake of environmental information) versus internally directed attention (rejection of environmental stimuli and focusing on memory/planning processes). This study investigated brain direct current (DC) potential shifts—which are discussed to represent different states of cortical activation—of tasks that require intake and rejection of environmental information under noise. It was hypothesized that without background noise rejection tasks would show more positive DC potential changes compared to intake tasks and that under noise both kinds of tasks would show positive DC shifts as an expression of cortical inhibition caused by noise. DC potential shifts during intake and rejection tasks were analyzed at 16 standard locations in 45 persons during irrelevant speech or white noise vs. control condition. Without noise, rejection tasks were associated with more positive DC potential changes compared to intake tasks. During background noise, however, this difference disappeared and both kinds of tasks led to positive DC shifts. Results suggest—besides some limitations—that noise modulates selective attention mechanisms by switching to an environmental information processing and noise rejection mode, which could represent a suggested “attention shift”. Implications for fMRI studies as well as for public health in learning and performance environments including susceptible persons are discussed.
Highlights
Environmental acoustic noise is known to have—besides health effects [1,2,3,4,5,6,7]—a number of adverse effects on human information processing by modulating attention [8,9,10,11]
The interaction of Noise ×Direction of Attention (F(1,43) = 4.46, p = 0.040) indicates that in the control condition rejection tasks are associated with more positive direct current (DC) potential changes compared to intake tasks (Figures 1 and 4), in the noise condition, DC shifts of intake tasks became more positive and reached the level of rejection tasks (Figures 1–4)
A trend for an effect of modality was observed in the interaction of Location ×Modality (F(15,29) = 1.82, p = 0.080), with confidence intervals indicating more positive DC potentials for verbal tasks compared to figural tasks at electrode P3
Summary
Environmental acoustic noise (even of low to moderate intensity) is known to have—besides health effects [1,2,3,4,5,6,7]—a number of adverse effects on human information processing by modulating attention [8,9,10,11]. The function of attention has already been described by James [12] “Every one [sic]. It implies withdrawal of some things in order to deal effectively with others, and is a condition which has a real opposite in the confused, dazed, scatter-brained state, which in French is called distraction, and Zerstreutheit in German” pp. Facilitation of relevant information and inhibition of non-relevant stimuli are seen as basic underlying mechanisms of selective attention [13]. This means that during complex cognitive tasks, non-task-relevant information is filtered out as an expression of selective attention. Rejection of environmental stimuli would take place in tasks that require attention to be directed towards internal processing or in cases where environmental stimuli would affect current information processing
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