Kramer Alexander, Röder Brigitte, Bruns Patrick
Biological Psychology and Neuropsychology, University of Hamburg, Hamburg, Germany.
Front Integr Neurosci. 2020 Jan 17;13:74. doi: 10.3389/fnint.2019.00074. eCollection 2019.
In an ever-changing environment, crossmodal recalibration is crucial to maintain precise and coherent spatial estimates across different sensory modalities. Accordingly, it has been found that perceived auditory space is recalibrated toward vision after consistent exposure to spatially misaligned audio-visual stimuli (VS). While this so-called ventriloquism aftereffect (VAE) yields internal consistency between vision and audition, it does not necessarily lead to consistency between the perceptual representation of space and the actual environment. For this purpose, feedback about the true state of the external world might be necessary. Here, we tested whether the size of the VAE is modulated by external feedback and reward. During adaptation audio-VS with a fixed spatial discrepancy were presented. Participants had to localize the sound and received feedback about the magnitude of their localization error. In half of the sessions the feedback was based on the position of the VS and in the other half it was based on the position of the auditory stimulus. An additional monetary reward was given if the localization error fell below a certain threshold that was based on participants' performance in the pretest. As expected, when error feedback was based on the position of the VS, auditory localization during adaptation trials shifted toward the position of the VS. Conversely, feedback based on the position of the auditory stimuli reduced the visual influence on auditory localization (i.e., the ventriloquism effect) and improved sound localization accuracy. After adaptation with error feedback based on the VS position, a typical auditory VAE (but no visual aftereffect) was observed in subsequent unimodal localization tests. By contrast, when feedback was based on the position of the auditory stimuli during adaptation, no auditory VAE was observed in subsequent unimodal auditory trials. Importantly, in this situation no visual aftereffect was found either. As feedback did not change the physical attributes of the audio-visual stimulation during adaptation, the present findings suggest that crossmodal recalibration is subject to top-down influences. Such top-down influences might help prevent miscalibration of audition toward conflicting visual stimulation in situations in which external feedback indicates that visual information is inaccurate.
在不断变化的环境中，跨模态重新校准对于在不同感官模态之间维持精确且连贯的空间估计至关重要。因此，研究发现，在持续暴露于空间上不匹配的视听刺激（VS）后，感知到的听觉空间会向视觉重新校准。虽然这种所谓的腹语后效（VAE）在视觉和听觉之间产生了内部一致性，但它不一定会导致空间感知表征与实际环境之间的一致性。为此，关于外部世界真实状态的反馈可能是必要的。在此，我们测试了VAE的大小是否受外部反馈和奖励的调节。在适应过程中，呈现具有固定空间差异的音频 - VS。参与者必须对声音进行定位，并收到关于其定位误差大小的反馈。在一半的实验环节中，反馈基于VS的位置，而在另一半中，反馈基于听觉刺激的位置。如果定位误差低于基于参与者预测试表现的某个阈值，则给予额外的金钱奖励。正如预期的那样，当误差反馈基于VS的位置时，适应试验期间的听觉定位会朝着VS的位置移动。相反，基于听觉刺激位置的反馈减少了视觉对听觉定位的影响（即腹语效应），并提高了声音定位的准确性。在基于VS位置的误差反馈进行适应后，在随后的单模态定位测试中观察到了典型的听觉VAE（但没有视觉后效）。相比之下，当在适应过程中反馈基于听觉刺激的位置时，在随后的单模态听觉试验中未观察到听觉VAE。重要的是，在这种情况下也未发现视觉后效。由于反馈在适应过程中并未改变视听刺激的物理属性，目前的研究结果表明跨模态重新校准受到自上而下的影响。这种自上而下的影响可能有助于在外部反馈表明视觉信息不准确的情况下，防止听觉因冲突的视觉刺激而出现校准错误。
