Enhanced audio-tactile multisensory interaction in a peripersonal task after echolocation

Abstract

Peripersonal space (PPS) is created by a multisensory interaction between different sensory modalities and can be modified by experience. In this article, we investigated whether an auditory training, inside the peripersonal space area, can modify the PPS around the head in sighted participants. The auditory training was based on echolocation. We measured the participant’s reaction times to a tactile stimulation on the neck, while task-irrelevant looming auditory stimuli were presented. Sounds more strongly affect tactile processing when located within a limited distance from the body. We measured spatially dependent audio-tactile interaction as a proxy of PPS representation before and after an echolocation training. We found a significant speeding effect on tactile RTs after echolocation, specifically when sounds where around the location where the echolocation task was performed. This effect could not be attributed to a task repetition effect nor to a shift of spatial attention, as no changes of PPS were found in two control groups of participants, who performed the PPS task after either a break or a temporal auditory task (with stimuli located at the same position of echolocation task). These findings show that echolocation affects multisensory processing inside PPS representation, likely to better represent the space where external stimuli, have to be localized. Electronic supplementary material The online version of this article (10.1007/s00221-019-05469-3) contains supplementary material, which is available to authorized users.

Do sounds near the hand facilitate tactile reaction times? Four experiments and a meta-analysis provide mixed support and suggest a small effect size

“…As this 1-4 s passes without a target, the target then becomes increasingly likely to occur at subsequent time points (a 'hazard function'). This expectancy effect likely influenced participants' RTs in many reports (Ardizzi and Ferri 2018;Canzoneri et al 2012Canzoneri et al , 2013aFerri et al 2015a, b;Galli et al 2015;Hobeika et al 2018;Maister et al 2015;Noel et al 2015a, b;Serino et al 2015;Teneggi et al 2013;Tonelli et al 2019), but was controlled for only by Pfeiffer et al (2018)-RTs were approximately 16 ms shorter for targets later as compared to earlier in the trial.…”

“…Criterion for assessing peripersonal space Most studies used a simple effect of distance to assess peripersonal space, by comparing 'far' with 'near' sounds. However, six kinds of experiments defined peripersonal space as a difference between a particular sound distance and a tactile 'baseline', rather than as a difference between 'near' and 'far' sounds (Noel et al 2015a;Pfeiffer et al 2018 Experiment 1;Serino et al 2015;Tonelli et al 2019). Because these 'baseline' data were not acquired in balanced factorial designs including all possible time points with both tactile and audiotactile conditions, or included in the ANOVA, the reported post hoc comparisons using them are invalid and do not explain the reported effects.…”

“…Sounds have included changes in intensity played over headphones (Ferri et al 2015a, b), which cannot provide distance information (Kolarik et al 2016), and are thus irrelevant to peripersonal space. Other studies used headphone-presented sounds filtered using generic head-related transfer functions to create more realistic spatial sound (Hobeika et al 2018;Pfeiffer et al 2018), or arrays of two (Serino et al 2007), four (Galli et al 2015), seven (Tonelli et al 2019), or eight (Noel et al 2015a, b) speakers. The sounds varied between constant white noise (Serino et al 2007), white noise presented from different speakers sequentially (Galli et al 2015), changing amplitude pink noise (Canzoneri et al 2012), different kinds of noise (Ferri et al 2015b), and water bubbling (Hobeika et al 2018).…”

“…Tactile stimuli have been pulses of near-or abovethreshold electrical stimulation (Serino et al 2007), vibrations (Galli et al 2015), or air puffs (Teramoto et al 2013); presented to the finger (Serino et al 2007), arm or hand (Canzoneri et al 2012), cheek (Teneggi et al 2013), ear (Kitagawa et al 2005;Tajadura-Jiménez et al 2009), chest or back (Galli et al 2015), neck (Tonelli et al 2019), or head (Serino et al 2015;Pfeiffer et al 2018).…”

“…This is circular (Holmes 2007). Finally, in an experiment testing whether learning to 'echo-locate' influences peripersonal space, Tonelli et al (2019) excluded participants based on worse performance in the last 30 compared to the first 10 trials of a two-alternative forced-choice task. Although described as "inability to complete training" (p. 856), six of the included participants' performance was not significantly better than chance (i.e.…”