Negative emotion provides cues for orienting auditory spatial attention

"Rear bias" in spatial auditory perception: Attentional and affective vigilance to sounds occurring outside the visual field

Presented studies explored the rear bias phenomenon, that is, the attentional and affective bias to sounds occurring behind the listener. Physiological and psychological reactions (i.e., fEMG, EDA/SCR, Simple Reaction Task-SRT, and self-assessments of affect-related states) were measured in response to tones of different frequencies (Study 1) and emotional vocalizations (Study 2) presented in rear and front spatial locations. Results showed that emotional vocalizations, when located in the back, facilitate reactions related to attention orientation (i.e., auricularis muscle response and simple reaction times) and evoke higher arousal-both physiological (as measured by SCR) and psychological (self-assessment scale). Importantly, observed asymmetries were larger for negative and threat-related signals (e.g., anger) than positive/nonthreatening ones (e.g., achievement). By contrast, there were only small differences for the relatively higher frequency tones. The observed relationships are discussed in terms of one of the postulated auditory system's functions, which is monitoring of the environment in order to quickly detect potential threats that occur outside of the visual field (e.g., behind one's back).

Auditory and cross-modal attentional bias toward positive natural sounds: Behavioral and ERP evidence

Recently, researchers have expanded the investigation into attentional biases toward positive stimuli; however, few studies have examined attentional biases toward positive auditory information. In three experiments, the present study employed an emotional spatial cueing task using emotional sounds as cues and auditory stimuli (Experiment 1) or visual stimuli (Experiment 2 and Experiment 3) as targets to explore whether auditory or visual spatial attention could be modulated by positive auditory cues. Experiment 3 also examined the temporal dynamics of cross-modal auditory bias toward positive natural sounds using event-related potentials (ERPs). The behavioral results of the three experiments consistently demonstrated that response times to targets were faster after positive auditory cues than they were after neutral auditory cues in the valid condition, indicating that healthy participants showed a selective auditory attentional bias (Experiment 1) and cross-modal attentional bias (Experiment 2 and Experiment 3) toward positive natural sounds. The results of Experiment 3 showed that N1 amplitudes were more negative after positive sounds than they were after neutral sounds, which further provided electrophysiological evidence that positive auditory information enhances attention at early stages in healthy adults. The results of the experiments performed in the present study suggest that humans exhibit an attentional bias toward positive natural sounds.

Exposure to arousal-inducing sounds facilitates visual search

Exposure to affective stimuli could enhance perception and facilitate attention via increasing alertness, vigilance, and by decreasing attentional thresholds. However, evidence on the impact of affective sounds on perception and attention is scant. Here, a novel aspect of affective facilitation of attention is studied: whether arousal induced by task-irrelevant auditory stimuli could modulate attention in a visual search. In two experiments, participants performed a visual search task with and without auditory-cues that preceded the search. Participants were faster in locating high-salient targets compared to low-salient targets. Critically, search times and search slopes decreased with increasing auditory-induced arousal while searching for low-salient targets. Taken together, these findings suggest that arousal induced by sounds can facilitate attention in a subsequent visual search. This novel finding provides support for the alerting function of the auditory system by showing an auditory-phasic alerting effect in visual attention. The results also indicate that stimulus arousal modulates the alerting effect. Attention and perception are our everyday tools to navigate our surrounding world and the current findings showing that affective sounds could influence visual attention provide evidence that we make use of affective information during perceptual processing.

Auditory attentional selection is biased by reward cues

Auditory attention theories suggest that humans are able to decompose the complex acoustic input into separate auditory streams, which then compete for attentional resources. How this attentional competition is influenced by motivational salience of sounds is, however, not well-understood. Here, we investigated whether a positive motivational value associated with sounds could bias the attentional selection in an auditory detection task. Participants went through a reward-learning period, where correct attentional selection of one stimulus (CS+) lead to higher rewards compared to another stimulus (CS-). We assessed the impact of reward-learning by comparing perceptual sensitivity before and after the learning period, when CS+ and CS- were presented as distractors for a different target. Performance decreased after reward-learning when CS+ was a distractor, while it increased when CS- was a distractor. Thus, the findings show that sounds that were associated with high rewards captures attention involuntarily. Additionally, when successful inhibition of a particular sound (CS-) was associated with high rewards then it became easier to ignore it. The current findings have important implications for the understanding of the organizing principles of auditory perception and provide, for the first time, clear behavioral evidence for reward-dependent attentional learning in the auditory domain in humans.