Contingent sounds change the mental representation of one’s finger length

Abstract

Mental body-representations are highly plastic and can be modified after brief exposure to unexpected sensory feedback. While the role of vision, touch and proprioception in shaping body-representations has been highlighted by many studies, the auditory influences on mental body-representations remain poorly understood. Changes in body-representations by the manipulation of natural sounds produced when one’s body impacts on surfaces have recently been evidenced. But will these changes also occur with non-naturalistic sounds, which provide no information about the impact produced by or on the body? Drawing on the well-documented capacity of dynamic changes in pitch to elicit impressions of motion along the vertical plane and of changes in object size, we asked participants to pull on their right index fingertip with their left hand while they were presented with brief sounds of rising, falling or constant pitches, and in the absence of visual information of their hands. Results show an “auditory Pinocchio” effect, with participants feeling and estimating their finger to be longer after the rising pitch condition. These results provide the first evidence that sounds that are not indicative of veridical movement, such as non-naturalistic sounds, can induce a Pinocchio-like change in body-representation when arbitrarily paired with a bodily action.

The Influence of Auditory Cues on Bodily and Movement Perception

“…Importantly, in this condition, visually altering perceived limb size, namely minimizing the limb, is an effective analgesic (Moseley et al, 2008). The findings of studies in this review, showing that auditory cues can dynamically modulate perceived body size (Tajadura-Jiménez et al, 2012, 2017b, 2018, raise the possibility that use of auditory cues, such as a descending/ascending pitch, may have similar effects on pain, particularly when combined with other sensory cues (multisensory). Indeed, multisensory visuotactile body resizing illusions have been shown to result in significantly more analgesia in people with painful knee osteoarthritis than visual illusions alone (Stanton et al, 2018).…”

“…These bi-directional influences between audition and action support the potential for profound influences on perception. Given the rapidly growing literature on auditory influences on movement and body perception (Tajadura-Jiménez et al, 2015a, 2016, 2017b, 2018Stanton et al, 2017), a review is clearly warranted. No such published review currently exists in this space as multisensory research has tended to focus on visual influences on body and movement perception, for example, see Moseley (2005); Moseley et al (2008), and Stanton et al (2018), and previous reviews of audiotactile interaction are based on passive tactile stimulation -e.g., see Kitagawa and Spence (2006) and Occelli et al (2011b).…”

Auditory-induced body distortions in children and adults

“…The auditory stimuli were similar to the ones described in 36 and consisted of pure tones (3000 ms duration and 44.1-kHz sample rate) of increasing ('ascending' tone: 700 to 1200 Hz), decreasing ('descending' tone: 700 to 200 Hz) or constant ('constant' tone: 700 Hz) frequency. To prevent clipping, a 10 ms onset/offset ramp was added in the auditory stimuli, which were presented at a 60 dB sound level.…”

“…All participants were able to say whether the sound was ascending, descending or constant, and whether they felt their finger being pulled or pressed by the experimenter. Note that, contrary to 36 , the participants' finger was pulled or pressed by an experimenter rather than asking the participant to self-touch their own finger. This was motivated mostly by providing a type of stimulation similar across participants and particularly to prevent children from being distracted by this manual task rather than by the illusion.…”

“…The analysis revealed a main effect of Finger, F(1, 58) = 47.83, p < 0.001, ηp 2 = 0.45, a Group × Finger interaction, F(1, 58) = 4.78, p = 0.03, ηp 2 = 0.08, and a three-way interaction between Sound, Finger and Group, F(2, 116) = 12.72, p = 0.03, ηp 2 = 0.06. To further explore the three-way interaction, we conducted two further analyses: one to investigate the effects of sound when the finger was pulled (i.e., elongation); the other to investigate the effect of sound when the finger was pressed (i.e., shortening), as also done in the study by 36 .…”