University of York, Heslington, York, YO10 5DD, UK.
University of Lincoln, Brayford Pool, Lincoln, LN6 7TS, UK.
Exp Brain Res. 2024 Feb;242(2):451-462. doi: 10.1007/s00221-023-06759-7. Epub 2024 Jan 2.
Bodily resizing illusions typically use visual and/or tactile inputs to produce a vivid experience of one's body changing size. Naturalistic auditory input (an input that reflects the natural sounds of a stimulus) has been used to increase illusory experience during the rubber hand illusion, whilst non-naturalistic auditory input can influence estimations of finger length. We aimed to use a non-naturalistic auditory input during a hand-based resizing illusion using augmented reality, to assess whether the addition of an auditory input would increase both subjective illusion strength and measures of performance-based tasks. Forty-four participants completed the following three conditions: no finger stretching, finger stretching without tactile feedback and finger stretching with tactile feedback. Half of the participants had an auditory input throughout all the conditions, whilst the other half did not. After each condition, the participants were given one of the following three performance tasks: stimulated (right) hand dot touch task, non-stimulated (left) hand dot touch task, and a ruler judgement task. Dot tasks involved participants reaching for the location of a virtual dot, whereas the ruler task concerned estimates of the participant's own finger on a ruler whilst the hand was hidden from view. After all trials, the participants completed a questionnaire capturing subjective illusion strength. The addition of auditory input increased subjective illusion strength for manipulations without tactile feedback but not those with tactile feedback. No facilitatory effects of audio were found for any performance task. We conclude that adding auditory input to illusory finger stretching increased subjective illusory experience in the absence of tactile feedback but did not affect performance-based measures.
身体大小错觉通常使用视觉和/或触觉输入来产生身体大小变化的生动体验。自然听觉输入（反映刺激自然声音的输入）已被用于增加橡胶手错觉中的错觉体验，而非自然听觉输入会影响手指长度的估计。我们旨在使用基于手的大小错觉的非自然听觉输入，通过增强现实，来评估是否增加听觉输入会增加主观错觉强度和基于表现的任务的测量。44 名参与者完成了以下三种条件：无手指拉伸、无触觉反馈的手指拉伸和有触觉反馈的手指拉伸。一半的参与者在所有条件下都有听觉输入，而另一半则没有。在每种条件之后，参与者都要完成以下三个表现任务中的一个：受刺激（右手）的点触任务、不受刺激（左手）的点触任务和尺子判断任务。点任务涉及参与者伸手去触摸虚拟点的位置，而尺子任务涉及在隐藏手的情况下估计参与者自己手指在尺子上的位置。在所有试验之后，参与者完成了一份问卷，以捕获主观错觉强度。在没有触觉反馈的情况下，听觉输入的增加增加了操纵的主观错觉强度，但在有触觉反馈的情况下则没有。在任何表现任务中，音频都没有产生促进作用。我们得出的结论是，在没有触觉反馈的情况下，向错觉手指拉伸添加听觉输入会增加主观错觉体验，但不会影响基于表现的测量。
