Attention capture by auditory significant stimuli: semantic analysis follows attention switching

Abstract

Event-related potentials (ERPs) were recorded from the scalp to investigate a long-standing controversy in auditory attention research, namely when the 'breakthrough of the unattended' takes place in the human brain. Nine subjects classified visual stimuli appearing 300 ms after task-irrelevant standard tones (80%, i.e. P = 0.8) or novel sounds (20%, i.e. P = 0.2) into odd/even categories. After the recording session, subjects scored the novel sounds as to whether they had any particular meaning (identifiable) or were perceived as a burst of noise (non-identifiable), and performance and ERPs were analysed according to this classification. A control condition, in which the visual stimuli were presented with no sounds, showed that subjects covertly monitored the task-irrelevant sounds during visual task-performance, and a further condition, in which the auditory and visual stimuli appeared regardless of each other, made it possible to trace the processing of the distracters during allocation of attention outside the auditory environment. Results yielded identical N1-enhancement for the two types of novel sounds, indicating similar attention switching triggered to these two types of unexpected sounds. However, there was a stronger orientating of attention towards identifiable novel sounds, as indicated both by behavioural distraction and by larger novelty-P3. Furthermore, this stronger orientating of attention was due to the sounds being contingent on the visual stimuli, as no increase in novelty-P3 to identifiable novel sounds was observed in the control condition, in which the sounds occurred outside the attentional set. Therefore, provided that the N1-enhancement reflects a call for focal attention, and novelty-P3 the effective orientating of attention towards the eliciting sounds, the present results suggest that semantic analysis of significant sounds occurs after a transitory switch of attention towards the eliciting stimuli. Moreover, as the novelty-P3 increase in amplitude was observed only when subjects covertly monitored the sounds, the present data suggest that semantic analysis of irrelevant sounds depends on the top-down cognitive influences of the attentional set.

Familiarity affects environmental sound processing outside the focus of attention: An event-related potential study

“…Typically, the N400 is not elicited when sounds are processed outside the focus of attention (cf. Mecklinger et al, 1997;Escera et al, 2003). Correspondingly, the present data only indicate a semantic analysis of the familiar stimulus after a physical deviance attracted attention to the sounds.…”

“…Whereas the reviewed effects were observed when sounds were ignored, familiarity effects for complex environmental sounds were so far only addressed for attended sounds (e.g., Lenz et al, 2007;van Petten and Rheinfelder, 1995) or attention-capturing, ''novel" sounds (e.g., Escera et al, 2003;Mecklinger et al, 1997). For the first time, the present study compared the processing of a familiar and an unfamiliar environmental sound when sounds were presented as regular, non-deviant items outside the focus of attention.…”

“…in a familiar context. Other studies observed effects related to the familiarity of a deviant or novel sound only subsequently to the MMN, either on the P3a (e.g., Escera et al, 2003;Neuloh and Curio, 2004;Holeckova et al, 2006;Wetzel and Schröger, 2007; for sound familiarity effects on novelty processing see also Cycowicz and Friedman, 1998) or outside the MMN/P3a complex (e.g., Mecklinger et al, 1997;Roye et al, 2007;Wetzel and Schröger, 2007).…”

Gaining Mismatch Negativity! Improving Auditory Phoneme Discrimination by Literacy Training ? A Pre-Post Event-Related Potential Study

“…However, more recent research has found an enhancement of the MMN amplitude when stimuli are attended [24]. This enhancement of amplitude was found to be associated to frontal generators of the MMN, namely IFG, but not to temporal generators of the MMN, namely STG [25,26].…”

Human striatal activation reflects degree of stimulus saliency

“…1) implemented in previous studies (Escera et al, 1998(Escera et al, , 2003. In each run, a single digit number (2, 3, 4, 5, 6, 7, 8, or 9) appeared for 200 ms in the center of the screen, with a 3.3 s interstimulus interval.…”