Crossmodal Congruency Task Research Articles

The left–right reversed visual feedback of the hand affects multisensory interaction within peripersonal space

The interaction between vision and touch, known as the crossmodal congruency effect, has been extensively investigated in several research studies. Recent studies have revealed that the crossmodal congruency effect involves body representations. However, it is unclear how bodily information (e.g., location, posture, motion) is linked to visual and tactile inputs. Three experiments were conducted to investigate this issue. In Experiment 1, participants performed a crossmodal congruency task in which both their hand appearance and the motor trajectories were left–right reversed. The results showed that the crossmodal congruency effect was not observed in the reversal condition, whereas participants showed significant crossmodal congruency in the control condition, in which there was no visual manipulation of the hand. In Experiments 2 and 3, where either the hand appearance or motor trajectory was left–right reversed individually, a significant crossmodal congruency effect was observed. This study demonstrated that visual manipulation of hand appearance and motor trajectories both affected the crossmodal congruency effect, although neither showed a dominant effect that solely altered the crossmodal congruency effect. The present results provide insights into the relationship between visual-tactile interactions and bodily information.

Towards Visual-Tactile Integration of Shoulder and Hand Using Immersive Virtual Reality.

Shoulder-controlled hand neuroprostheses are wearable devices designed to assist hand function in people with cervical spinal cord injury (SCI). They use preserved shoulder movements to control artificial actuators. Due to the concurrent afferent (i.e., shoulder proprioception) and visual (i.e., hand response) feedback, these wearables may affect the user's body somatosensory representation. To investigate this effect, we propose an experimental paradigm that uses immersive virtual reality (VR) environment to emulate the use of a shoulder-controlled hand neuroprostheses and an adapted version of a visual-tactile integration task (i.e., Crossmodal Congruency Task) as an assessment tool. Data from seven non-disabled participants validates the experimental setup, with preliminary statistical analysis revealing no significant difference across the means of VR and visual-tactile integration tasks. The results serve as a proof-of-concept for the proposed paradigm, paving the way for further research with improvements in the experimental design and a larger sample size.

Embodiment of supernumerary robotic limbs in virtual reality

The supernumerary robotic limb system expands the motor function of human users by adding extra artificially designed limbs. It is important for us to embody the system as if it is a part of one’s own body and to maintain cognitive transparency in which the cognitive load is suppressed. Embodiment studies have been conducted with an expansion of bodily functions through a “substitution” and “extension”. However, there have been few studies on the “addition” of supernumerary body parts. In this study, we developed a supernumerary robotic limb system that operates in a virtual environment, and then evaluated whether the extra limb can be regarded as a part of one’s own body using a questionnaire and whether the perception of peripersonal space changes with a visuotactile crossmodal congruency task. We found that the participants can embody the extra-limbs after using the supernumerary robotic limb system. We also found a positive correlation between the perceptual change in the crossmodal congruency task and the subjective feeling that the number of one’s arms had increased (supernumerary limb sensation). These results suggest that the addition of an extra body part may cause the participants to feel that they had acquired a new body part that differs from their original body part through a functional expansion.

Peripersonal space around the upper and the lower limbs

Peripersonal space (PPS), the space closely surrounding the body, is typically characterised by enhanced multisensory integration. Neurophysiological and behavioural studies have consistently shown stronger visuo-tactile integration when a visual stimulus is presented close to the tactually stimulate body part in near space (within PPS) than in far space. However, in the majority of these studies, tactile stimuli were delivered to the upper limbs, torso and face. Therefore, it is not known whether the space surrounding the lower limbs is characterised by similar multisensory properties. To address this question, we asked participants to complete two versions of the classic visuo-tactile crossmodal congruency task in which they had to perform speeded elevation judgements of tactile stimuli presented to the dorsum of the hand and foot while a simultaneous visual distractor was presented at spatially congruent or incongruent locations either in near or far space. In line with existing evidence, when the tactile target was presented to the hand, the size of the crossmodal congruency effect (CCE) decreased in far as compared to near space, suggesting stronger visuo-tactile multisensory integration within PPS. In contrast, when the tactile target was presented to the foot, the CCE decreased for visual distractors in near than far space. These findings show systematic differences between the representation of PPS around upper and lower limbs, suggesting that the multisensory properties of the different body part-centred representations of PPS are likely to depend on the potential actions performed by the different body parts.

Empathy as a predictor of peripersonal space: Evidence from the crossmodal congruency task

To investigate whether individual differences in Empathy predict the characteristics of Peripersonal Space (PPS) representations, we asked participants to complete the IRI questionnaire and a visuo-tactile crossmodal congruency task (CCT) as an index of PPS. In the CCT, they responded to the elevation of a tactile target while ignoring a visual distractor presented at the same (i.e. congruent) or different (i.e. incongruent) elevation. The target-distractor distance was also manipulated in depth, with visual distractors randomly presented at near, middle or far locations (0 cm, 25 cm or 50 cm). The near and middle crossmodal congruency effects (CCE) were inversely related to participants’ scores on the Empathic Concern sub-scale (EC). Furthermore, the slope of participants’ CCE across locations was related to EC scores, with flatter slopes for higher EC individuals. Thus, higher EC individuals showed reduced visuo-tactile integration responses within PPS and a reduced differentiation between PPS and extra-personal space (EPS).

Modulation of Bodily Self-Consciousness by Self and External Touch.

The full body illusion (FBI) is a bodily illusion based on the application of multisensory conflicts that induce changes in bodily self-consciousness (BSC). This has been used to study cognitive brain mechanisms underlying body ownership and related aspects of self-consciousness. Typically, such paradigms employ external passive multisensory stimulation, thus neglecting the possible contributions of self-generated action and haptic cues to body ownership. In this article, the effects of both external and voluntary self-touch on BSC were examined with a robotics-based FBI paradigm. We compared the effects of classical passive visuotactile stimulation and active self-touch (in which experimental participants had a sense of agency over the tactile stimulation) on the FBI. We evaluated these effects using a questionnaire, crossmodal congruency task, and measurements of changes in self-location. The results indicated that both synchronous passive visuotactile stimulation and synchronous active self-touch induced illusory ownership over a virtual body, without significant differences in their magnitudes. However, the FBI induced by active self-touch was associated with a larger drift in self-location towards the virtual body. These results show that movement-related signals arising from self-touch impact the BSC not only for hand ownership but also for torso-centered body ownership and related aspects of BSC.

Visual-Tactile Spatial Multisensory Interaction in Adults With Autism and Schizophrenia.

Background: Individuals with autism spectrum disorder (ASD) and schizophrenia (SZ) exhibit multisensory processing difficulties and social impairments, with growing evidence that the former contributes to the latter. However, this work has largely reported on separate cohorts, introducing method variance as a barrier to drawing broad conclusions across studies. Further, very few studies have addressed touch, resulting in sparse knowledge about how these two clinical groups may integrate somatic information with other senses.Methods: In this study, we compared adults with ASD (n = 29), SZ (n = 24), and typical developmental histories (TD, n = 37) on two tasks requiring visual-tactile spatial multisensory processing. In the first task (crossmodal congruency), participants judged the location of a tactile stimulus in the presence or absence of simultaneous visual input that was either spatially congruent or incongruent, with poorer performance for incongruence an index of spatial multisensory interaction. In the second task, participants reacted to touch in the presence or absence of dynamic visual stimuli that appeared to approach or recede from the body. Within a certain radius around the body, defined as peripersonal space (PPS), an approaching visual or auditory stimulus reliably speeds reaction times (RT) to touch; outside of this radius, in extrapersonal space (EPS), there is no multisensory effect. PPS can be defined both by its size (radius) and slope (sharpness of the PPS-EPS boundary). Clinical measures were administered to explore relations with visual-tactile processing.Results: Neither clinical group differed from controls on the crossmodal congruency task. The ASD group had significantly smaller and more sharply-defined PPSs compared to the other two groups. Small PPS size was related to social symptom severity across groups, but was largely driven by the TD group, without significant effects in either clinical group.Conclusions: These results suggest that: (1) spatially static visual-tactile facilitation is intact in adults with ASD and SZ, (2) spatially dynamic visual-tactile facilitation impacting perception of the body boundary is affected in ASD but not SZ, and (3) body boundary perception is related to social-emotional function, but not in a way that maps on to clinical status.

Seeing an image of the hand affects performance on a crossmodal congruency task for sequences of events.

The crossmodal congruency effect (CCE) is augmented when viewing an image of a hand compared to an object. It is unclear if this contextual effect extends to a non-spatial CCE. Here, participants discriminated the number of tactile vibrations delivered to the hand whilst ignoring visual distractors on images of their own or another's hand or an object. The CCE was not modulated by stimulus context. Viewing one's hand from a third person perspective increased errors relative to viewing an object (Experiment 1). Errors were reduced when viewing hands, from first or third person perspectives, with additional identity markers (Experiments 2 and 3). Our results suggest no effect of context on the non-spatial CCE and that differences in task performance between hand and object images depend on their visual properties. These findings are discussed in light of the relationship between body representation and perception of body-centred stimuli in the temporal domain.

Altered updating of bodily and spatial representations after tool-use in complex regional pain syndrome

Distorted representations of the body and peripersonal space are common in complex regional pain syndrome (CRPS), and might modulate its symptoms (eg, asymmetric limb temperature). In pain-free people, such representations are malleable, and update when we interact with objects in our environment (eg, during tool-use). Distortions are also common after immobilisation, but quickly normalise once movement is regained. We tested the hypothesis that people with CRPS have problems updating bodily and spatial representations, which contributes to the maintenance of their distorted representations by preventing normalization. We also explored spatially defined modulations of hand temperature asymmetries, and any influence of updating bodily and spatial representations on this effect. Thirty-six people with unilateral CRPS (18 upper limb and 18 lower limb) and 36 pain-free controls completed tool-use tasks considered to alter body and peripersonal space representations (measured using tactile distance judgements and a visuotactile crossmodal congruency task, respectively). We also tested how the arrangement (crossed and uncrossed) of the hands and tools affected hand temperature. In upper-limb CRPS, the nonaffected arm representation updated normally, but the affected arm representation updated in the opposite to normal direction. A similar pattern was seen in lower-limb CRPS, although not significant. Furthermore, people with CRPS showed more pronounced updating of peripersonal space than the controls. We did not observe any modulation of hand temperature asymmetries by the arrangement of hands or tools. Our findings show enhanced malleability of bodily and spatial representations in CRPS, which may suggest that central mechanisms are altered in this condition.

Audiovisual Integration During Joint Action: No Effects for Motion Discrimination and Temporal Order Judgment Tasks.

In daily life, humans constantly process information from multiple sensory modalities (e.g., visual and auditory). Information across sensory modalities may (or may not) be combined to form the perception of a single event via the process of multisensory integration. Recent research has suggested that performing a spatial crossmodal congruency task jointly with a partner affects multisensory integration. To date, it has not been investigated whether multisensory integration in other crossmodal tasks is also affected by performing a task jointly. To address this point, we investigated whether joint task performance also affects perceptual judgments in a crossmodal motion discrimination task and a temporal order judgment task. In both tasks, pairs of participants were presented with auditory and visual stimuli that might or might not be perceived as belonging to a single event. Each participant in a pair was required to respond to stimuli from one sensory modality only (e.g., visual stimuli only). Participants performed both individual and joint conditions. Replicating earlier multisensory integration effects, we found that participants' perceptual judgments were significantly affected by stimuli in the other modality for both tasks. However, we did not find that performing a task jointly modulated these crossmodal effects. Taking this together with earlier findings, we suggest that joint task performance affects crossmodal results in a manner dependent on how these effects are quantified (i.e., via responses time or accuracy) and the specific task demands (i.e., whether tasks require processing stimuli in terms of location, motion, or timing).

Visual and Proprioceptive Influences on Tactile Spatial Processing in Adults with Autism Spectrum Disorders.

Children with autism spectrum disorders (ASDs) often exhibit altered representations of the external world. Consistently, when localizing touch, children with ASDs were less influenced than their peers by changes of the stimulated limb's location in external space [Wada et al., Scientific Reports 2015, 4(1), 5985]. However, given the protracted development of an external-spatial dominance in tactile processing in typically developing children, this difference might reflect a developmental delay rather than a set suppression of external space in ASDs. Here, adults with ASDs and matched control-participants completed (a) the tactile temporal order judgment (TOJ) task previously used to test external-spatial representation of touch in children with ASDs and (b) a tactile-visual cross-modal congruency (CC) task which assesses benefits of task-irrelevant visual stimuli on tactile localization in external space. In both experiments, participants localized tactile stimuli to the fingers of each hand, while holding their hands either crossed or uncrossed. Performance differences between hand postures reflect the influence of external-spatial codes. In both groups, tactile TOJ-performance markedly decreased when participants crossed their hands and CC-effects were especially large if the visual stimulus was presented at the same side of external space as the task-relevant touch. The absence of group differences was statistically confirmed using Bayesian statistical modeling: adults with ASDs weighted external-spatial codes comparable to typically developed adults during tactile and visual-tactile spatio-temporal tasks. Thus, atypicalities in the spatial coding of touch for children with ASDs appear to reflect a developmental delay rather than a stable characteristic of ASD. Autism Res 2019, 12: 1745-1757. © 2019 International Society for Autism Research, Wiley Periodicals, Inc. LAY SUMMARY: A touched limb's location can be described twofold, with respect to the body (right hand) or the external world (right side). Children and adolescents with autism spectrum disorder (ASD) reportedly rely less than their peers on the external world. Here, adults with and without ASDs completed two tactile localization tasks. Both groups relied to the same degree on external world locations. This opens the possibility that the tendency to relate touch to the external world is typical in individuals with ASDs but emerges with a delay.

Crossmodal congruency effect scores decrease with repeat test exposure.

The incorporation of feedback into a person’s body schema is well established. The crossmodal congruency task (CCT) is used to objectively quantify incorporation without being susceptible to experimenter biases. This visual-tactile interference task is used to calculate the crossmodal congruency effect (CCE) score as a difference in response time between incongruent and congruent trials. Here we show that this metric is susceptible to a learning effect that causes attenuation of the CCE score due to repeated task exposure sessions. We demonstrate that this learning effect is persistent, even after a 6 month hiatus in testing. Two mitigation strategies are proposed: 1. Only use CCE scores that are taken after learning has stabilized, or 2. Use a modified CCT protocol that decreases the task exposure time. We show that the modified and shortened CCT protocol, which may be required to meet time or logistical constraints in laboratory or clinical settings, reduced the impact of the learning effect on CCT results. Importantly, the CCE scores from the modified protocol were not significantly more variable than results obtained with the original protocol. This study highlights the importance of considering exposure time to the CCT when designing experiments and suggests two mitigation strategies to improve the utility of this psychophysical assessment.

Experimentally induced pain does not influence updating of peripersonal space and body representations following tool-use.

Representations of the body and peripersonal space can be distorted for people with some chronic pain conditions. Experimental pain induction can give rise to similar, but transient distortions in healthy individuals. However, spatial and bodily representations are dynamic, and constantly update as we interact with objects in our environment. It is unclear whether induced pain disrupts the mechanisms involved in updating these representations. In the present study, we sought to investigate the effect of induced pain on the updating of peripersonal space and body representations during and following tool-use. We compared performance under three conditions (pain, active placebo, neutral) on a visuotactile crossmodal congruency task and a tactile distance judgement task to measure updating of peripersonal space and body representations, respectively. Consistent with previous findings, the difference in crossmodal interference from visual distractors in the same compared to opposite visual field to the tactile target was less when tools were crossed than uncrossed. This suggests an extension of peripersonal space to incorporate the tips of the tools. Also consistent with previous findings, estimates of the felt tactile distance judgements decreased after active tool-use. In contrast to our predictions, however, we found no evidence that pain interfered with performance on either task when compared to the control conditions. Our findings suggest that the updating of peripersonal space and body representations is not disrupted by induced pain. That is, experiencing acute pain does not give rise to distorted representations of the body and peripersonal space that can be present in people with chronic pain conditions.

Assessing the quality of supplementary sensory feedback using the crossmodal congruency task

Advanced neural interfaces show promise in making prosthetic limbs more biomimetic and ultimately more intuitive and useful for patients. However, approaches to assess these emerging technologies are limited in scope and the insight they provide. When outfitting a prosthesis with a feedback system, such as a peripheral nerve interface, it would be helpful to quantify its physiological correspondence, i.e. how well the prosthesis feedback mimics the perceived feedback in an intact limb. Here we present an approach to quantify this aspect of feedback quality using the crossmodal congruency effect (CCE) task. We show that CCE scores are sensitive to feedback modality, an important characteristic for assessment purposes, but are confounded by the spatial separation between the expected and perceived location of a stimulus. Using data collected from 60 able-bodied participants trained to control a bypass prosthesis, we present a model that results in adjusted-CCE scores that are unaffected by percept misalignment which may result from imprecise neural stimulation. The adjusted-CCE score serves as a proxy for a feedback modality’s physiological correspondence or ‘naturalness’. This quantification approach gives researchers a tool to assess an aspect of emerging augmented feedback systems that is not measurable with current motor assessments.

A third arm - Design of a bypass prosthesis enabling incorporation.

A variety of factors affect the performance of a person using a myoelectric prosthesis, including increased control noise, reduced sensory feedback, and muscle fatigue. Many studies use able-bodied subjects to control a myoelectric prosthesis using a bypass socket in order to make comparisons to movements made with intact limbs. Depending on the goals of the study, this approach can also allow for greater subject numbers and more statistical power in the analysis of the results. As we develop assessment tools and techniques to evaluate how peripheral nerve interfaces impact prosthesis incorporation, involving normally limbed subjects in the studies becomes challenging. We have designed a novel bypass prosthesis to allow for the assessment of prosthesis incorporation in able-bodied subjects. Incorporation of a prosthetic hand worn by a normally limbed subject requires that the prosthesis is a convincing, functional extension of their own body. We present the design and development of the bypass prosthesis with special attention to mounting position and angle of the prosthetic hand, the quality of the control system and the responsiveness of the feedback. The bypass prosthesis has been fitted with a myoelectrically-controlled hand that has been instrumented to measure the forces applied to the thumb, index, and middle fingers. The prosthetic hand was mounted on the bypass socket such that it is the same length as the subject's intact limb but at a medial rotation angle of 20° to prevent visual occlusion of the prosthetic hand. Force feedback is provided in the form of electrical stimulation, vibration, or force applied to the intact limb with milliseconds of delay. Preliminary data results from a cross-modal congruency task are included showing evidence of prosthesis incorporation in able-bodied subjects. This bypass will allow able-bodied subjects to participate in research studies that require the use of a prosthetic limb while also allowing the subjects to sense that the prosthesis is an extension of the body.

Ignoring Irrelevant Information: Enhanced Intermodal Attention in Synaesthetes.

Despite the fact that synaesthetes experience additional percepts during their inducer-concurrent associations that are often unrelated or irrelevant to their daily activities, they appear to be relatively unaffected by this potentially distracting information. This might suggest that synaesthetes are particularly good at ignoring irrelevant perceptual information coming from different sensory modalities. To investigate this hypothesis, the performance of a group of synaesthetes was compared to that of a matched non-synaesthete group in two different conflict tasks aimed at assessing participants' abilities to ignore irrelevant information. In order to match the sensory modality of the task-irrelevant distractors (vision) with participants' synaesthetic attentional filtering experience, we tested only synaesthetes experiencing at least one synaesthesia subtype triggering visual concurrents (e.g., grapheme-colour synaesthesia or sequence-space synaesthesia). Synaesthetes and controls performed a classic flanker task (FT) and a visuo-tactile cross-modal congruency task (CCT) in which they had to attend to tactile targets while ignoring visual distractors. While no differences were observed between synaesthetes and controls in the FT, synaesthetes showed reduced interference by the irrelevant distractors of the CCT. These findings provide the first direct evidence that synaesthetes might be more efficient than non-synaesthetes at dissociating conflicting information from different sensory modalities when the irrelevant modality correlates with their synaesthetic concurrent modality (here vision).

The contribution of response conflict, multisensory integration, and body-mediated attention to the crossmodal congruency effect.

The crossmodal congruency task is a consolidated paradigm for investigating interactions between vision and touch. In this task, participants judge the elevation of a tactile target stimulus while ignoring a visual distracter stimulus that may occur at a congruent or incongruent elevation, thus engendering a measure of visuo-tactile interference (crossmodal congruency effect, CCE). The CCE reflects perceptual, attentional, and response-related factors, but their respective roles and interactions have not been set out yet. In two experiments, we used the original version of the crossmodal congruency task as well as ad hoc manipulations of the experimental setting and of the participants' posture for characterizing the contributions of multisensory integration, body-mediated attention, and response conflict to the CCE. Results of the two experiments consistently showed that the largest amount of variance in the CCE is explained by the reciprocal elevation of visual and tactile stimuli. This finding is compatible with a major role of response conflict for the CCE. Weaker yet distinguishable contributions come from multisensory integration, observed in the absence of response conflict, and from hand-mediated attentional binding, observed with the modified posture and in the presence of response conflict. Overall, this study informs the long-standing debate about mechanisms underlying the CCE by revealing that the visuo-tactile interference in this task is primarily due to the competition between opposite response tendencies, with an additional contribution of multisensory integration and hand-mediated attentional binding.

Investigating the spatial and temporal modulation of visuotactile interactions in older adults.

Previous research has shown that spatially and temporally disparate multisensory events are more likely to interact for older adults. For visuotactile interactions, this suggests that the representation of peripersonal space is expanded and temporal perception within this space is less precise. Previously, visuotactile space has been found to expand horizontally into the opposite hemispace, and here we sought to replicate and extend this by exploring both horizontal and vertical space from the hand. Moreover, we investigated whether both spatial and temporal domains are affected for an individual, which have previously been measured using distinct tasks and different participants. We presented a modified cross-modal congruency task (Poole et al. in Multisens Res. doi: 10.1163/22134808-00002475 , 2015a) to thirty older participants (age range 65-85 years), with unisensory tactile performance equated for each individual. For the temporal manipulation, the timings of visual distractors and tactile targets were offset. For the spatial manipulation, visual distractors were presented from multiple positions in ipsilateral and contralateral hemispaces. Whilst the temporal modulation of visuotactile interactions for older adults was equivalent to that observed in young adults, spatial modulation was reduced; significant visuotactile interactions were observed for visual distractors presented in the same and opposite hemispace to the stimulated hand, in the lower visual field. This suggests an expanded representation of visuotactile space surrounding the hand in older adults, which occurs horizontally into the contralateral hemispace only, rather than expanding both vertically and horizontally. This is likely to have consequences for perception of space and goal-directed action in ageing.

Adapting the Crossmodal Congruency Task for Measuring the Limits of Visual-Tactile Interactions Within and Between Groups.

The crossmodal congruency task (CCT) is a commonly used paradigm for measuring visual-tactile interactions and how these may be influenced by discrepancies in space and time between the tactile target and visual distractors. The majority of studies which have used this paradigm have neither measured, nor attempted to control, individual variability in unisensory (tactile) performance. We have developed a version of the CCT in which unisensory baseline performance is constrained to enable comparisons within and between participant groups. Participants were instructed to discriminate between single and double tactile pulses presented to their dominant hand, at their own approximate threshold level. In Experiment 1, visual distractors were presented at -30 ms, 100 ms, 200 ms and 400 ms stimulus onset asynchronies. In Experiment 2, ipsilateral visual distractors were presented 0 cm, 21 cm, and 42 cm vertically from the target hand, and 42 cm in a symmetrical, contralateral position. Distractors presented -30 ms and 0 cm from the target produced a significantly larger congruency effect than at other time points and spatial locations. Thus, the typical limits of visual-tactile interactions were replicated using a version of the task in which baseline performance can be constrained. The usefulness of this approach is supported by the observation that tactile thresholds correlated with self-reported autistic traits in this non-clinical sample. We discuss the suitability of this adapted version of the CCT for measuring visual-tactile interactions in populations where unisensory tactile ability may differ within and between groups.

Sliding perspectives: dissociating ownership from self-location during full body illusions in virtual reality.

Bodily illusions have been used to study bodily self-consciousness and disentangle its various components, among other the sense of ownership and self-location. Congruent multimodal correlations between the real body and a fake humanoid body can in fact trigger the illusion that the fake body is one's own and/or disrupt the unity between the perceived self-location and the position of the physical body. However, the extent to which changes in self-location entail changes in ownership is still matter of debate. Here we address this problem with the support of immersive virtual reality. Congruent visuotactile stimulation was delivered on healthy participants to trigger full body illusions from different visual perspectives, each resulting in a different degree of overlap between real and virtual body. Changes in ownership and self-location were measured with novel self-posture assessment tasks and with an adapted version of the cross-modal congruency task. We found that, despite their strong coupling, self-location and ownership can be selectively altered: self-location was affected when having a third person perspective over the virtual body, while ownership toward the virtual body was experienced only in the conditions with total or partial overlap. Thus, when the virtual body is seen in the far extra-personal space, changes in self-location were not coupled with changes in ownership. If a partial spatial overlap is present, ownership was instead typically experienced with a boosted change in the perceived self-location. We discussed results in the context of the current knowledge of the multisensory integration mechanisms contributing to self-body perception. We argue that changes in the perceived self-location are associated to the dynamical representation of peripersonal space encoded by visuotactile neurons. On the other hand, our results speak in favor of visuo-proprioceptive neuronal populations being a driving trigger in full body ownership illusions.