Mechanisms underlying auditory and cross-modal emotional attentional biases: Engagement with and disengagement from aversive auditory stimuli

Transcranial Direct Current Stimulation (tDCS) over the left dorsolateral prefrontal cortex reduced attentional bias toward natural emotional sounds

Previous research has indicated that the left dorsolateral prefrontal cortex (DLPFC) exerts an influence on attentional bias toward visual emotional information. However, it remains unclear whether the left DLPFC also play an important role in attentional bias toward natural emotional sounds. The current research employed the emotional spatial cueing paradigm, incorporating natural emotional sounds of considerable ecological validity as auditory cues. Additionally, high-definition transcranial direct current stimulation (HD-tDCS) was utilized to examine the impact of left dorsolateral prefrontal cortex (DLPFC) on attentional bias and its subcomponents, namely attentional engagement and attentional disengagement. The results showed that (1) compared to sham condition, anodal HD-tDCS over the left DLPFC reduced the attentional bias toward positive and negative sounds; (2) anodal HD-tDCS over the left DLPFC reduced the attentional engagement toward positive and negative sounds, whereas it did not affect attentional disengagement away from natural emotional sounds. Taken together, the present study has shown that left DLPFC, which was closely related with the top-down attention regulatory function, plays an important role in auditory emotional attentional bias.

The emotion of sound target modulates the auditory gaze cueing effect

The auditory gaze cueing effect (auditory-GCE) is a faster response to auditory targets at an eye-gaze cue location than at a non-cue location. Previous research has found that auditory-GCE can be influenced by the integration of both gaze direction and emotion conveyed through facial expressions. However, it is unclear whether the emotional information of auditory targets can be cross-modally integrated with gaze direction to affect auditory-GCE. Here, we set neutral faces with different gaze directions as cues and three emotional sounds (fearful, happy, and neutral) as targets to investigate how the emotion of sound target modulates the auditory-GCE. Moreover, we conducted a controlled experiment using arrow cues. The results show that the emotional content of sound targets influences the auditory-GCE but only for those induced by facial cues. Specifically, fearful sounds elicit a significantly larger auditory-GCE compared to happy and neutral sounds, indicating that the emotional content of auditory targets plays a modulating role in the auditory-GCE. Furthermore, this modulation appears to occur only at a higher level of social meaning, involving the integration of emotional information from a sound with social gaze direction, rather than at a lower level, which involves the integration of direction and auditory emotion.

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.