Replicating and Extending Hemispheric Asymmetries in Auditory Distraction: No Metacognitive Awareness for the Left-Ear Disadvantage for Changing-State Sounds

Two experiments explored hemispheric asymmetries in auditory distraction by manipulating the spatial location of presentation of to-be-ignored sound. Previous research revealed a left-ear disadvantage for the presentation of changing-state sequences during short-term serial recall (Hadlington et al., 2004; 2006), but did not provide a direct measure of the changing-state effect as no steady-state condition was incorporated. Experiment 1 addressed this by comparing changing-state with steady-state sequences in a visual-verbal serial recall task, and confirmed that the additional disruption produced via left-ear presentation stemmed from the acoustically varying nature of the sound. This left-ear disadvantage for the changing-state effect highlights right hemisphere dominance for processing acoustic variation within unattended sound. Using the same stimuli, Experiment 2 replicated these results and gained insight into participant’s metacognitive monitoring of the disruptive potential of auditory distractors. Participants prospectively rated the extent to which they would be distracted by steady-state and changing-state sequences presented to the left ear, right ear, or both ears, and judged whether the sounds had a beneficial or detrimental effect on their performance after each trial. Participants showed both prospective and retrospective awareness that changing-state sequences were more disruptive than steady-state sequences (cf. Bell et al., 2021). However, participants did not expect disruption to vary by auditory location and were unaware that changing-state sequences were more disruptive when presented to the left ear, relative to the right ear or both ears. Therefore, individuals have metacognitive awareness of the greater disruptive impact of changing- over steady-state sound, but not the accompanying left-ear disadvantage. Implications of these findings are considered in the context of theoretical accounts of auditory distraction.两项实验通过操纵待忽略声音的呈现空间位置，探究了听觉分心（auditory distraction）中的大脑半球不对称性（hemispheric asymmetries）。既往研究表明，在短时系列回忆（short-term serial recall）任务中，呈现变化状态序列（changing-state sequences）时会出现左耳劣势效应（Hadlington等，2004；2006），但由于未纳入稳态条件，未能直接测量变化状态效应的大小。实验1通过在视觉言语系列回忆任务中对比变化状态序列与稳态序列，弥补了这一研究局限，并证实左耳呈现所引发的额外干扰，源于声音的声学变异性本质。这种针对变化状态效应的左耳劣势，凸显了右半球在加工未被注意声音的声学变化时的主导地位。实验2采用相同刺激材料重复了上述结果，并深入剖析了被试对听觉分心物干扰潜力的元认知监控（metacognitive monitoring）能力。被试需前瞻性评分左耳、右耳或双耳呈现的稳态序列与变化状态序列对自身的分心程度，并在每轮试次结束后判断这些声音对任务表现产生了有益还是有害影响。结果显示，被试兼具前瞻性与回溯性意识，能够意识到变化状态序列相比稳态序列的干扰性更强（参照Bell等，2021）。然而，被试并未预期听觉呈现位置会带来干扰程度的差异，也未察觉到相较于右耳或双耳呈现，变化状态序列在左耳呈现时的干扰性更强。综上，个体能够元认知到变化状态声音相较稳态声音具有更强的干扰效应，但无法意识到其伴随的左耳劣势效应。本研究的理论内涵将结合听觉分心的相关理论框架展开讨论。