Article

“That’s not a real body”: Identifying stimulus qualities that modulate synaesthetic experiences of touch

Authors:
To read the full-text of this research, you can request a copy directly from the authors.

No full-text available

Request Full-text Paper PDF

To read the full-text of this research,
you can request a copy directly from the authors.

... Importantly, the same cortical regions, most notably the SII, are also related to mirror-touch synesthesia. Mirror-touch synesthetes consciously feel a tactile sensation on their own face while observing another person being touched on the face (Blakemore et al., 2005;Ward, 2007, 2013;Holle et al., 2011Holle et al., , 2013. On the other hand, the anterior insula (aIC) has been considered as an important locus of interoceptive perception (i.e., the sense of the internal physiological condition of the body; Craig, 2002;Tsakiris et al., 2007;Suzuki et al., 2013). ...
... Second, we propose the neural mechanisms of bimodal neurons in VIP and PFG areas in macaque monkeys (Ishida et al., 2010), assuming the presence of a shared generative model for both self and other bodies in these brain areas, similarly to the PC account of the mirror neuron system (Kilner et al., 2007). Thereafter, we determine whether the proposed framework can explain vicarious touch and mirror-touch synesthesia in human SII and insular cortices (Banissy and Ward, 2007;Holle et al., 2011;Banissy and Ward, 2013;Holle et al., 2013). Finally, we will extend the PC model for shared body recognition to affective aspects of shared experience between self and others (i.e., empathy), which is possibly organized in the human insular cortex. ...
... As mentioned above, in human brain imaging studies, vicarious touch is characterized by activity in both the primary and secondary somatosensory cortices (SI and SII) when observing others' bodies being touched (Keysers et al., 2004;Ebisch et al., 2008;Keysers and Gazzola, 2009;Kuehn et al., 2013Kuehn et al., , 2014. In addition, people with mirror-touch synesthesia consciously perceive fictitious touch sensations when observing another's body being touched, which is associated with SII and insular cortices Ward, 2007, 2013;Holle et al., 2011Holle et al., , 2013. Although one possible explanation for vicarious touch comes from the mirror system-which predicts the sensory consequence of observed actions (Banissy et al., 2009;Seth, 2014)-this phenomenon may well be explained by sharing touch-perceived bodily state, rather than sharing action, with others. ...
... Although the visuo-tactile interference task of Banissy and Ward (2007) has been shown to offer a good way of identifying people with MTS, it requires bespoke equipment that is not readily accessible and requires different labs to establish their own baseline measures (tailored to their own equipment). An alternative approach that we (Holle, Banissy, Wright, Bowling, & Ward, 2011) and others (e.g., Baron-Cohen et al., 2016;Medina & De Pasquale, 2017) have used is to present participants with movies depicting touch and note the frequency and/or intensity of any felt tactile sensations. But how many tactile sensations need to be reported to meet the criteria for having MTS-one stimulus, all stimuli, or somewhere in between? ...
... But how many tactile sensations need to be reported to meet the criteria for having MTS-one stimulus, all stimuli, or somewhere in between? For example, Holle et al. (2011) reported that 66% of stimuli depicting touch to a human elicited a synaesthetic response in their MTS sample, but the inter-individual variation was very large (range = 14% to 100%). In their recent study, Baron-Cohen et al. (2016) reported a different measure (average intensity), and the range of scores is unknown. ...
... We examine how it relates to other kinds of vicarious experience (Experiment 1) and the socio-cognitive differences of people who score highly on this measure (Experiment 2). Experiment 1 uses a similar approach to that of Holle et al. (2011), Baron-Cohen et al. (2016), and others in that we present videos depicting touch and related experiences (pain, itch) and determine the selfreported synaesthetic characteristics. We aim to determine whether there are clear categorical differences between people at high and low ends of the measure or whether MTS occurs on a continuum. ...
Article
Full-text available
People with mirror-touch synaesthesia (MTS) report tactile sensations on their own body when seeing another person being touched. Although this has been associated with heightened empathy and emotion perception, this finding has been disputed. Here, we conduct two experiments to explore this relationship further. In Experiment 1, we develop a new screening measure for MTS. We show that MTS is related to vicarious experiences more generally, but is not a simple exaggerated version of normality. For example, people with MTS report videos of scratching as “touch” rather than “itchiness” and have localized sensations when watching others in pain. In Experiment 2, we show that MTS is related to increased emotional empathy to others and better ability to read facial expressions of emotion, but other measures of empathy are normal. In terms of theoretical models, we propose that this is more consistent with a qualitative difference in the ability to selectively inhibit the other and attend to the self.
... These findings are consistent with a role for sensorimotor processes in wider aspects of social perception (Adolphs et al., 2000;Banissy et al., 2010Banissy et al., , 2012Pitcher et al., 2008;Shamay-Tsoory et al., 2009). Finally, although most of the research has used facial stimuli, the basic phenomenology is preserved when other body parts are presented, including presenting stimuli from different perspectives (Holle et al., 2011). Interestingly, the intensity of the synaesthetic touch is reduced when dummy body parts and dummy faces are used (Holle et al., 2011). ...
... Finally, although most of the research has used facial stimuli, the basic phenomenology is preserved when other body parts are presented, including presenting stimuli from different perspectives (Holle et al., 2011). Interestingly, the intensity of the synaesthetic touch is reduced when dummy body parts and dummy faces are used (Holle et al., 2011). This suggests that the synaesthesia depends on inferred animacy (i.e. ...
... We also extended the design to include dummy faces. Dummies are visually more similar to real bodies than they are to objects, but in terms of their propensity to induce mirror-touch synaesthesia they rarely evoke mirror-touch sensations (Holle et al., 2011). ...
Article
Full-text available
Observing touch is known to activate regions of the somatosensory cortex but the interpretation of this finding is controversial (e.g. does it reflect the simulated action of touching or the simulated reception of touch?). For most people, observing touch is not linked to reported experiences of feeling touch but in some people it is (mirror-touch synaesthetes). We conducted an fMRI study in which participants (mirror-touch synaesthetes, controls) watched movies of stimuli (face, dummy, object) being touched or approached. In addition we examined whether mirror touch synaesthesia is associated with local changes of grey and white matter volume in the brain using VBM (Voxel-based Morphometry). Both synaesthetes and controls activated the somatosensory system (primary and secondary somatosensory cortices, SI and SII) when viewing touch, and the same regions were activated (by a separate localizer) when feeling touch - i.e. there is a mirror system for touch. However, when comparing the two groups, we found evidence that SII seems to play a particular important role in mirror-touch synaesthesia: in synaesthetes, but not in controls, posterior SII was active for watching touch to a face (in addition to SI and posterior temporal lobe); activity in SII correlated with subjective intensity measures of mirror-touch synaesthesia (taken outside the scanner), and we observed an increase in grey matter volume within the SII of the synaesthetes' brains. In addition, the synaesthetes showed hypo-activity when watching touch to a dummy in posterior SII. We conclude that the secondary somatosensory cortex has a key role in this form of synaesthesia.
... More recently, a further spatial mapping has been suggested by who report two variants of experience within the mirrored frame of reference related to the direction of touch: One in which direction of experience is matched in a body-centered reference frame and another in a viewer-centered reference frame. The spatial mappings of anatomical or mirrored experience have been shown to be consistent across body parts (e.g., if someone has a mirrored experience for observed touch to the face they would also experience this for observed touch to the hands from a third person perspective; and consistent across time (Holle, Banissy, Wright, Bowling, & Ward, 2011). ...
... A minority of individuals also report experiencing tactile sensations when observing touch to objects, either on their hands or body, in addition to when observing touch to humans Banissy et al., 2009a). Observing touch to dummy body parts tend to elicit fewer, and less intense, self-reported sensations, thus making dummies more comparable to objects than the human body (Holle et al., 2011). However, observing touch to a rubber hand has been reported to be sufficient to elicit the Rubber Hand Illusion (the feeling that one's own hand is replaced by the dummy hand), even in the absence of physical touch, in two participants with MTS but not controls (Aimola ; see also Giummarra et al., 2010). ...
... There have been a number of studies examining perceptual and cognitive characteristics involved in developmental MTS. This includes studies examining the nature of the inducer in MTS (e.g., Banissy et al., 2009a;Holle et al., 2011) and broader traits that have been found to be different in individuals that have MTS including sensory sensitivity, empathy, and emotion processing Banissy, Walsh, & Ward, 2009;. The precise mechanisms that contribute to MTS and how they link with wider traits observed in MTS remain a topic of debate. ...
Article
We thoroughly enjoyed Ward and Banissy's Discussion Paper on mirror-touch synesthesia. The authors contrast two theories for explaining this phenomenon-the Threshold Theory and their Self-Other Theory. Ward and Banissy note that the Self-Other Theory garners support from studies that have tested individuals with mirror-touch synesthesia using the rubber hand paradigm. In this Commentary, we provide further support for the Self-Other Theory by drawing on findings from control participants without mirror-touch synesthesia tested with two different no-touch rubber hand paradigms-one paradigm makes it easier while the other makes it more difficult to make the self-other distinction.
... Participants were asked to report only sensations that occurred (or increased) when they observed the motion or touch in the movie. This task resembles that used by Holle, Banissy, Wright, Bowling, and Ward (2011), who report the effectiveness of video stimuli depicting touch to real bodies to induce touch referral in mirror-touch synesthetes. Thermal stimuli (implied heat and cold) were included to test relative referral of thermal properties; studies examining sensory referral of thermal qualities have thus far reported very low rates of this type of sensory referral (e.g. ...
... Thermal stimuli (implied heat and cold) were included to test relative referral of thermal properties; studies examining sensory referral of thermal qualities have thus far reported very low rates of this type of sensory referral (e.g. Holle et al., 2011;Ramachandran & Brang, 2009). ...
... For these reasons we suggest that heightened sensory referral is a general phenomenon arising from the reduction of sensory feedback to the brain. Referral was weaker for thermal stimuli, however, as also reported by Holle et al. (2011) and Ramachandran and Brang (2009). This discrepancy suggests that the referral experienced by the dental patients was caused by similar mirror processes as in other sensory referral studies, as the pattern of stronger referral for touch than thermal sensations was upheld. ...
Article
Mirror neurons allow us to covertly simulate the sensation and movement of others. If mirror neurons are sensory and motor neurons, why do we not actually feel this simulation- like "mirror-touch synesthetes"? Might afferent sensation normally inhibit mirror representations from reaching consciousness? We and others have reported heightened sensory referral to phantom limbs and temporarily anesthetized arms. These patients, however, had experienced illness or injury of the deafferented limb. In the current study we observe heightened sensory and motor referral to the face after unilateral nerve block for routine dental procedures. We also obtain double-blind, quantitative evidence of heightened sensory referral in healthy participants completing a mirror-touch confusion task after topical anesthetic cream is applied. We suggest that sensory and motor feedback exist in dynamic equilibrium with mirror representations; as feedback is reduced, the brain draws more upon visual information to determine- perhaps in a Bayesian manner- what to feel.
... They make no errors if they see a flash on the other person's face. Nor do they make error if they see an object or a dummy being stroked (Holle et al., 2011). MTS is thus clearly related to perceiving another subject experiencing tactile sensations. ...
... So far it has only been shown that the temperature is not shared (Holle et al., 2011). ...
... For most of us, observing another person being touched activates neural regions in the somatosensory cortex that are also involved in experiencing touch (e.g., Keysers et al., 2004Keysers et al., , 2010Ebisch et al., 2008;Schaefer et al., 2012), however this activation does not lead to overt sensations of the observed event: we typically do not feel any tactile sensation when observing the tactile experience of others. On the contrary, people with MTS, approximately 1.6% of the population (Banissy et al., 2009), do experience overt tactile sensations to the observed event: they feel tactile sensations on their body when simply seeing touch to another's body (Blakemore et al., 2005;Holle et al., 2011;Banissy, 2013). These experiences are reported to be automatic (Banissy and Ward, 2007), enduring (Holle et al., 2011), and may be associated with broader differences in social perception (Banissy and Ward, 2007;Banissy et al., 2011;Goller et al., 2013). ...
... On the contrary, people with MTS, approximately 1.6% of the population (Banissy et al., 2009), do experience overt tactile sensations to the observed event: they feel tactile sensations on their body when simply seeing touch to another's body (Blakemore et al., 2005;Holle et al., 2011;Banissy, 2013). These experiences are reported to be automatic (Banissy and Ward, 2007), enduring (Holle et al., 2011), and may be associated with broader differences in social perception (Banissy and Ward, 2007;Banissy et al., 2011;Goller et al., 2013). ...
... Another interesting instance of tactile illusions can be observed in synesthesia, that is a pathological condition in which a stimulation in one sensory modality automatically induces a conscious sensory experience in a different modality (Watson et al., 2014). Crucially, it has been reported the existence of a mirror-touch form of synesthesia: there are people who experience a tactile stimulation on a given part of their body when they see another individual being touched on the same body part (Blakemore et al., 2005;Banissy et al., 2009;Holle et al., 2011). ...
... It is worth noticing that expectancies could be generated not only on the basis of visual stimulation, but also on the basis of any sensory information relevant for the emergence of sensory awareness. For instance, it is known that mirror-touch synesthesia (Banissy et al., 2009;Holle et al., 2011), delusional body ownership (Pia et al., 2013a) and tactile illusions in spinal cord injury (Tidoni et al., 2014) occur when observing touch delivered on the human body but not on objects or dummies. This means that stored internal representations impose constraints on the emergence of a specific tactile experience. ...
Article
Full-text available
In the present paper, we will attempt to gain hints regarding the nature of tactile awareness in humans. At first, we will review some recent literature showing that an actual tactile experience can emerge in absence of any tactile stimulus (e.g., tactile hallucinations, tactile illusions). According to the current model of tactile awareness, we will subsequently argue that such (false) tactile perceptions are subserved by the same anatomo-functional mechanisms known to underpin actual perception. On these bases, we will discuss the hypothesis that tactile awareness is strongly linked to expected rather than actual stimuli. Indeed, this hypothesis is in line with the notion that the human brain has a strong predictive, rather than reactive, nature.
... The literature on vicarious touch has repeatedly shown that there is a sensitivity for human touch in eliciting mirror-like sensations. Specifically, MTS occurs more frequently and more intensely when viewing touch on another person compared to touch on inanimate objects (Banissy & Ward, 2007;Holle, Banissy, Wright, Bowling, & Ward, 2011;Ward et al., 2018). To establish whether this pattern of responding was also present in our sample, we compared MT scores in response to human versus dummy touch videos. ...
... Second, there were quantitative but not qualitative differences in vicarious tactile responses between those with and without ASMR; both groups' MT responses were stronger for human touch compared to inanimate (dummy) touch; and the two groups had largely similar responses to human scratching videos. These patterns reflect those typically found in mirror touch research (Banissy & Ward, 2007;Holle et al., 2011;Ward et al., 2018). Importantly, if the ASMR group were prone to over-responding to visually observed events in general, it is highly unlikely that they would produce these specific patterns of vicarious tactile responses. ...
Article
Full-text available
The characterisation of autonomous sensory meridian response (ASMR) as an audio-visual phenomenon overlooks how tactile experiences are not just perceptual concurrents of ASMR (i.e., tingling) but also commonly strong ASMR inducers. Here we systematically investigated whether ASMR-responders show altered tactile processing compared to controls. Using a screening measure of vicarious touch with a predefined cut-off for mirror-touch synaesthesia (MTS; a condition where tactile sensations are experienced when viewing, but not receiving, touch), we found that ASMR-responders had more frequent and intense vicarious touch experiences, as well as a strikingly higher incidence of MTS, than non-responders. ASMR-responders also reported greater reactivity to positive, but not negative, interpersonal touch. Correlations further showed these patterns to be more prevalent in those responders with stronger ASMR. We discuss the implications of our findings in terms of heightened sensory sensitivity, bodily awareness, and the underlying neuro-cognitive mechanisms driving vicarious tactile perception in ASMR and MTS.
... A further condition associating atypical socio-cognitive development with impaired self-other control is mirror-touch synaesthesia. Individuals with mirror-touch synaesthesia experience tactile sensations on their own body when observing touch to other individuals [28][29][30], and (less frequently) when observing touch to objects [29][30][31]. The experience has also been linked with broader differences in social perception and cognition, including heightened empathy [32,33] and emotion perception [34]. ...
... A further condition associating atypical socio-cognitive development with impaired self-other control is mirror-touch synaesthesia. Individuals with mirror-touch synaesthesia experience tactile sensations on their own body when observing touch to other individuals [28][29][30], and (less frequently) when observing touch to objects [29][30][31]. The experience has also been linked with broader differences in social perception and cognition, including heightened empathy [32,33] and emotion perception [34]. ...
Article
Full-text available
We review the evidence that an ability to achieve a precise balance between representing the self and representing other people is crucial in social interaction. This ability is required for imitation, perspective-taking, theory of mind and empathy; and disruption to this ability may contribute to the symptoms of clinical and sub-clinical conditions, including autismspectrumdisorder and mirror-touch synaesthesia. Moving beyond correlational approaches, a recent intervention study demonstrated that training participants to control representations of the self and others improves their ability to control imitative behaviour, and to take another’s visual perspective. However, it is unclear whether these effects apply to other areas of social interaction, such as the ability to empathize with others. We report original data showing that participants trained to increase self–other control in the motor domain demonstrated increased empathic corticospinal responses (Experiment 1) and self-reported empathy (Experiment 2), as well as an increased ability to control imitation. These results suggest that the ability to control self and other representations contributes to empathy as well as to other types of social interaction. © 2015 The Author(s) Published by the Royal Society. All rights reserved.
... Banissy and Ward [19] also reported that MT synaesthetes (N = 10) were significantly faster to name where a person was being touched on trials that were congruent with their synaesthetic experience of touch, and were significantly impaired in contrast to controls on incongruent trials. It is unclear if MT synaesthesia is specific to viewing a real person, rather than a dummy figure [20] or an object being touched [19] since in their Supplementary material Banissy and Ward [19] discuss some cases of MT synaesthesia also being induced by viewing objects being touched. Given the small samples that have been studied, the present study tests this specificity claim in a larger sample. ...
... Previous studies suggest that MT experiences are specific to viewing a human stimulus being touched [20]. The current study also found the mean rating for human clips was significantly higher than the mean rating for object clips, but the fact that viewing objects being touched did still trigger MT experiences in the MT group suggests that such experiences are not specific to viewing humans being touched. ...
Article
Full-text available
Research has linked Mirror-Touch (MT) synaesthesia with enhanced empathy. We test the largest sample of MT synaesthetes to date to examine two claims that have been previously made: that MT synaesthetes (1) have superior empathy; and (2) only ever experience their MT synaesthesia in response to viewing a person being touched. Given that autism has been suggested to involve deficits in cognitive empathy, we also test two predictions: that MT synaesthetes should (3) be less likely than general population individuals without MT synaesthesia to have an autism spectrum condition (ASC), if MT is characterized by superior empathy; and (4) have fewer autistic traits. We selected three groups: a pure MT synaesthesia group (N = 46), a pure grapheme-colour (GC) synaesthesia group (N = 36), and a typical control group without synaesthesia (N = 46). Participants took three measures of empathy and one measure of autistic traits. MT synaesthetes did not show enhanced empathy. In addition, 30% of all MT synaesthetes recruited into this study (N = 135) reported also having ASC, and MT synaesthetes showed higher autistic trait scores than controls. Finally, some MT experiences were reported in response to viewing objects being touched. Our findings dispute the views that MT synaesthesia is linked with enhanced empathy, is less likely to occur with ASC or elevated autistic traits, and is specific to seeing a person being touched.
... Indeed, for objects touching the body, activations in SI appears stronger when the visual stimulus suggests intense pain, such as when a needle is shown penetrating a hand deeply as opposed to pricking it, or if participants imagine that they are in a painful situation themselves (Bufalari et al., 2007; Keysers et al., 2010). The intensity of observed tactile stimulus can also modulate the intensity of the synaesthesic experience – touching the face with a knife tip or finger elicits a stronger synaesthetic sensation than using a feather (Holle et al., 2011). Second, SI is more active when viewing hands manipulating objects (e.g. ...
... Moreover, each hemisphere is more strongly activated when viewing actions conducted by a model's contralateral hand than when viewing actions conducted by an ipsilateral hand (Aziz-Zadeh et al. 2002), and mirror activations by the sight of touch are somatotopically organized, following the sensory homunculus magnification in SI (Blakemore et al., 2005; Schaefer, et al. 2009). Even in synaesthesic patients there is often an anatomical mapping in which, for instance, the observed touch to a left cheek is felt on their left cheek and activates the right SI (Blakemore et al., 2005; Holle et al., 2011). Through this anatomical mapping, SI may convey a simulation of the precise body location at which the touch occurred, hence providing somatotopically specific representations of other people's somatosensations. ...
Article
Brain imaging studies in humans have revealed the existence of a visuo-tactile system, which matches observed touch with felt touch. In this system, the primary somatosensory cortex (SI) appears to play a causal role in the visual processing of tactile events. Whether this visuo-tactile mechanism for touch in SI applies to the sight of 'any' touch, or whether it is restricted to the domain of body-related tactile experiences remains unresolved. To address this issue, repetitive transcranial magnetic stimulation (rTMS) was used to determine whether activity in SI is strictly related to the visual processing of human body-part interactions, or is also involved in processing the contact between inanimate objects, or between human body-parts and objects. The results show that rTMS over SI selectively impaired the processing of a contralateral visual stimulus depicting a human body-part being touched by a human agent, while it did not affect the visual perception of contact between objects, or between human body-parts and objects. Correlation analysis shows that this effect was associated with the intensity and embodiment of the observed touched. This result suggests that SI is more suited to represent social touch, contributing to our understanding of the effect of interpersonal tactile interactions between people.
... The affective meaning conveyed by interactive bodily touch has been shown to increase S1, S2, and insular activity (Bjornsdotter and Olausson, 2011; Kress et al., 2011). Observing human-based intentional touch causes stronger S1 activations (Ebisch et al., 2008;Kress et al., 2011) and engages tactile mirroring processes to a larger extent (Deschrijver et al., 2015;Holle et al., 2011;Streltsova and McCleery, 2014), compared to object-based non-intentional touch. These S1 activations are said to play a key role in understanding the affective consequences (Bolognini et al., 2013b) of tactile interactions between people (Rossetti et al., 2012). ...
... The 1.6% estimate comes from participants that objectively differ to control participants on behavioural tests designed to verify the presence of MTS, and therefore this conservative estimate and approach is considered best practice for studies on MTS. A prevalence of 1.6% also relates to the proportion of individuals that experience conscious response to observed touch to humans, but it is of note that some individuals also report vicarious touch in response to inanimate stimuli (such as objects or dummy body parts) (Banissy and Ward, 2007;Banissy et al., 2009;Holle et al., 2011). ...
Article
Full-text available
Touch is our most interpersonal sense, and so it stands to reason that we represent not only our own bodily experiences, but also those felt by others. This review will summarise brain and behavioural research on vicarious tactile perception (mirror touch). Specifically, we will focus on vicarious touch across the lifespan in typical and atypical groups, and will identify the knowledge gaps that are in urgent need of filling by examining what is known about how individuals differ within and between typical and atypical groups.
... 136 and p. 821). More recent studies document vision-touch synaesthesia in healthy individuals (see Banissy and Ward, 2007; Banissy et al., 2009a Banissy et al., , 2009b Banissy et al., , 2011 Blakemore et al., 2005; Holle et al., 2011, and for an overview, see Ward et al., 2008). Banissy et al. (2009a) have estimated the prevalence rate for vision-touch synaesthesia to be as high as 1.6 in 100, which makes it one of the most common forms of synaesthesia; the prevalence rate for colour-grapheme synaesthesia is approximately 1.4 in 100 (Simner et al., 2006). ...
... 3 Results for control participants who demonstrated positive proprioceptive drift: 60-sec trial, n ¼ 2 (.5 cm; 1 cm); 180-sec trial, n ¼ 3 (1 cm; 2 cm; 3 cm); 300-sec trial, n ¼ 4 (.5 cm; .5 cm; 1.5 cm; 4.5 cm). 4 A recent study of individuals with vision-touch synaesthesia (Holle et al., 2011) has shown that synaesthetic tactile sensation is less intense when a 'dummy' hand is used. This could mean that our participants may have experienced an even stronger rubber hand illusion if we had used a human hand instead of a prosthetic hand. ...
Article
For individuals with vision-touch synaesthesia, the sight of touch on another person elicits synaesthetic tactile sensation on the observer's own body. Here we used the traditional rubber hand paradigm (Botvinick and Cohen, 1998) and a no-touch rubber hand paradigm to investigate and to authenticate synaesthetic tactile sensation. In the traditional rubber hand paradigm, the participant views a prosthetic hand being touched by the Examiner while the participant's hand - hidden from view - is also touched by the Examiner. Synchronous stimulation of the prosthetic hand and the participant's hidden hand elicits the rubber hand illusion. It may seem to the participant that she is feeling touch at the location of the viewed prosthetic hand - visual capture of touch, and that the prosthetic hand is the participant's own hand - illusion of ownership. Thus, for participants who experience the traditional rubber hand illusion, tactile sensation on the participant's hidden hand is referred to the prosthetic hand. In our no-touch rubber hand paradigm, the participant views a prosthetic hand being touched by the Examiner but the participant's hand - hidden from view - is not touched by the Examiner. Questionnaire ratings indicated that only individuals with vision-touch synaesthesia experienced the no-touch rubber hand illusion. Thus, synaesthetic tactile sensation on the (untouched) hidden hand was referred to the prosthetic hand. These individuals also demonstrated proprioceptive drift (a change, from baseline, in proprioceptively perceived position) of the hidden hand towards the location of the prosthetic hand, and a pattern of increased proprioceptive drift with increased trial duration (60sec, 180sec, 300sec). The no-touch rubber hand paradigm was an excellent method to authenticate vision-touch synaesthesia because participants were naïve about the rubber hand illusion, and they could not have known how they were expected to perform on either the traditional or the no-touch rubber hand paradigm.
... Just as crossing the hands affects localisation of actual touch in individuals without VTS, it also affects localisation of synaesthetic tactile sensation in individuals with VTS. In a study by Holle et al (2011), individuals with VTS were shown crossed hands in a video: the left hand on the right side of the computer screen and the right hand on the left side of the computer screen, with fingers pointing to the top of the screen. When the viewed left hand on the right side of the screen received touch, seven of eight participants reported feeling sensation on their own left hand (a hand-centred reference frame), which was positioned to the left in an external reference frame. ...
Article
Two subtypes of vision-touch synaesthesia (VTS) have been identified. For anatomical VTS, sight of touch on another person elicits synaesthetic tactile sensation at the same location on the observer's own body (e.g., viewed touch on the left cheek elicits sensation on the observer's left cheek). For specular VTS, sight of touch on another person elicits synaesthetic tactile sensation at the mirror-reflected location (e.g., viewed touch on the left cheek elicits sensation on the observer's right cheek). Here we report two distinctly different patterns of sensation within the specular subtype. Both participants experienced synaesthetic tactile sensation on their right hand when they viewed unidirectional brushstrokes administered to a prosthetic left hand (positioned with fingers pointing toward the participant), but the direction of sensation matched the viewed touch in a hand-centred (spatial) reference frame for RS and in an external (viewer-centred) reference frame for NC. Competing reference frames affect how individuals with specular VTS experience synaesthetic tactile sensation.
... For each subtype, their experiences are reported to be automatic, enduring, and present since childhood (Banissy and Ward, 2007; Holle et al., 2011). While several studies have examined cognitive and perceptual characteristics of mirror-touch synesthesia (e.g., Banissy and Ward, 2007; Banissy et al., 2009, 2011; Holle et al., 2011; White and Aimola Davies, 2012; Aimola-Davies and White, 2013), there has been relatively less research that delineates the neural mechanisms that contribute to developmental mirror-touch. One common suggestion is that developmental mirrortouch synesthesia may be a function of atypical cortical excitability within neural regions supporting normal somatosensory mirroring. ...
Article
Full-text available
In recent years several studies have documented a near-universal tendency to vicariously represent the actions and sensations of others (e.g., see Keysers and Gazzola, 2009 for review). For example, observing another person experiencing pain activates neural regions involved in experiencing pain (e.g., Singer et al., 2004; Avenanti et al., 2005) or observing somebody being touched recruits regions of the somatosensory cortex involved in experiencing touch (e.g., Keysers et al., 2004, 2010; Ebisch et al., 2008; Schaefer et al., 2012). For most of us, these vicarious representations are implicit and do not lead to overt sensations of the observed events (e.g., we do not feel pain when observing pain to others). There are, however, a small number of individuals who do experience overt somatic sensations when observing others' tactile experiences (Ward et al., 2008; Osborn and Derbyshire, 2010; Fitzgibbon et al., 2012; Banissy, 2013). For example, in mirror-touch synesthesia observing touch or pain to others evokes a conscious tactile sensation on the synesthetes' own body (Banissy and Ward, 2007; Holle et al., 2011). This opinion piece seeks to discuss potential neural mechanisms that contribute to the developmental form of mirror-touch synesthesia (for descriptions of acquired forms of mirror-touch/pain synesthesia see Fitzgibbon et al., 2012; Goller et al., 2013), and the important role that self-other representations may have on vicarious experiences of touch in mirror-touch synesthesia.
... This feature of synesthetic mirror-touch might be related to a more general differential susceptibility to the involvement of somatosensory and interoceptive cortices into embodied simulation found in fMRI studies with non-synesthetic healthy subjects (Ebisch et al., 2008(Ebisch et al., , 2011. This suggests that top-down processes may also modulate the intensity of the synesthetic mirror-touch experience (Fitzgibbon et al., 2010;Holle et al., 2011). Different potential mechanisms of mirror-sensory synesthesia are discussed in the literature. ...
Article
Full-text available
Synesthesia is traditionally regarded as a phenomenon in which an additional non-standard phenomenal experience occurs consistently in response to ordinary stimulation applied to the same or another modality. Recent studies suggest an important role of semantic representations in the induction of synesthesia. In the present proposal we try to link the empirically grounded theory of sensory-motor contingency and mirror system based embodied simulation/emulation to newly discovered cases of swimming style-color synesthesia. In the latter color experiences are evoked only by showing the synesthetes a picture of a swimming person or asking them to think about a given swimming style. Neural mechanisms of mirror systems seem to be involved here. It has been shown that for mirror-sensory synesthesia, such as mirror-touch or mirror-pain synesthesia (when visually presented tactile or noxious stimulation of others results in the projection of the tactile or pain experience onto oneself), concurrent experiences are caused by overactivity in the mirror neuron system responding to the specific observation. The comparison of different forms of synesthesia has the potential of challenging conventional thinking on this phenomenon and providing a more general, sensory-motor account of synesthesia encompassing cases driven by semantic or emulational rather than pure sensory or motor representations. Such an interpretation could include top-down associations, questioning the explanation in terms of hard-wired structural connectivity. In the paper the hypothesis is developed that the wide-ranging phenomenon of synesthesia might result from a process of hyperbinding between "too many" semantic attribute domains. This hypothesis is supplemented by some suggestions for an underlying neural mechanism.
... When we are being touched, the touch sensation has a specific quality which assures us that "my body belongs to me." This feeling of body ownership is typically not experienced when we simply observe other people being touched but is confined to one's own body (but see Holle, Banissy, Wright, Bowling, & Ward, 2011). One way to investigate and experimentally manipulate this experience of body ownership is by means of the rubber hand illusion (RHI) (cf. ...
Article
The rubber hand illusion is one reliable way to experimentally manipulate the experience of body ownership. However, debate continues about the necessary and sufficient conditions eliciting the illusion. We measured proprioceptive drift and the subjective experience (via questionnaire) while manipulating two variables that have been suggested to affect the intensity of the illusion. First, the rubber hand was positioned either in a posturally congruent position, or rotated by 180°. Second, either the anatomically same rubber hand was used, or an anatomically incongruent one. We found in two independent experiments that a rubber hand rotated by 180° leads to increased proprioceptive drift during synchronous visuo-tactile stroking, although it does not lead to feelings of ownership (as measured by questionnaire). This dissociation between drift and ownership suggests that proprioceptive drift is not necessarily a valid proxy for the illusion when using hands rotated by 180°.
... While some participants' tactile experiences generalized to strangers and fictional characters, many reported that their mirror-touch responses were enhanced for—or even limited to—people with whom they feel close. Such reports are consistent with previous findings, like those showing that mirror-touch perceptions are stronger for observed touch of real bodies than of dummy bodies (n = 14; Holle et al., 2013). Ticker tape experiences also showed a wealth of individual differences, as reported in semi-structured interviews of participants recruited from our sample for another study (Chun and Hupé, 2013 [Abstract] ; ticker tape: 7 men, 11 women). ...
Article
Full-text available
A fundamental question in the field of synesthesia is whether it is associated with other cognitive phenomena. The current study examined synesthesia's connections with phenomenal traits of mirror-touch and ticker tape experiences, as well as the representation of the three phenomena in the population, across gender and domain of work/study. Mirror-touch is the automatic, involuntary experience of tactile sensation on one's own body when others are being touched. For example, seeing another person's arm being stroked can evoke physical touch sensation on one's own arm. Ticker tape is the automatic visualization of spoken words or thoughts, such as a teleprompter. For example, when spoken to, a ticker taper might see mentally the spoken words displayed in front of his face or as coming out of the speaker's mouth. To explore synesthesia's associations with these phenomena, a diverse group (n = 3743) was systematically recruited from eight universities and one public museum in France to complete an online screening. Of the 1017 eligible respondents, synesthetes (across all subtypes) reported higher rates of mirror-touch and ticker tape than non-synesthetes, suggesting that synesthesia is associated with these phenomenal traits. However, effect sizes were small and we could not rule out that response bias influenced these associations. Mirror-touch and ticker tape were independent. No differences were found across gender or domain of work and study in prevalence of synesthesia, mirror-touch or ticker tape. The prevalence of ticker tape, unknown so far, was estimated at about 7%, an intermediate rate between estimates of grapheme-color (2-4%) and sequence-space synesthesia (9-14%). Within synesthesia, grapheme-personification, also called ordinal-linguistic personification (OLP) was the most common subtype and was estimated around 12%. Co-occurences of the different types of synesthesia were higher than chance, though at the level of small effect sizes.
... rectangular geometrical objects [24]) and the pain neural network also responds to noxious stimuli applied to objects (e.g. a tomato [63] ). Experiments conducted in mirror-touch synesthetes demonstrate that they also experience moderate tactile sensation during the observation of dummy body parts or objects being touched [64]. Altogether, these observations suggest that the mirroring system does not work in a pure body-specific way. ...
Article
Full-text available
THE OBSERVATION OF CONSPECIFICS INFLUENCES OUR BODILY PERCEPTIONS AND ACTIONS: Contagious yawning, contagious itching, or empathy for pain, are all examples of mechanisms based on resonance between our own body and others. While there is evidence for the involvement of the mirror neuron system in the processing of motor, auditory and tactile information, it has not yet been associated with the perception of self-motion. We investigated whether viewing our own body, the body of another, and an object in motion influences self-motion perception. We found a visual-vestibular congruency effect for self-motion perception when observing self and object motion, and a reduction in this effect when observing someone else's body motion. The congruency effect was correlated with empathy scores, revealing the importance of empathy in mirroring mechanisms. The data show that vestibular perception is modulated by agent-specific mirroring mechanisms. The observation of conspecifics in motion is an essential component of social life, and self-motion perception is crucial for the distinction between the self and the other. Finally, our results hint at the presence of a "vestibular mirror neuron system".
... Watching touch to others also caused changes in mental representations of self in mirror-touch synesthetes, supporting the theory that differences in mapping of sensation as "self" or "other" may determine whether sensation is experienced consciously (Maister et al., 2013, Banissy and. Indeed, synesthetic touch is strongest for touch to real bodies and weaker for dummy bodies or pictures of bodies (Holle et al., 2011). Mirror-touch synesthesia may constitute an extreme version of normal sensory referral that has exceeded (or circumvented) the threshold for consciousness (Fitzgibbon et al., 2012). ...
Article
Motor imagery and perception- considered generally as forms of motor simulation- share overlapping neural representations with motor production. While much research has focused on the extent of this "common coding," less attention has been paid to how these overlapping representations interact. How do imagined, observed, or produced actions influence one another, and how do we maintain control over our perception and behavior? In the first part of this review we describe interactions between motor production and motor simulation, and explore apparent regulatory mechanisms that balance these processes. Next, we consider the somatosensory system. Numerous studies now support a "sensory mirror system" comprised of neural representations activated by either afferent sensation or vicarious sensation. In the second part of this review we summarize evidence for shared representations of sensation and sensory simulation (including imagery and observed sensation), and suggest that similar interactions and regulation of simulation occur in the somatosensory domain as in the motor domain. We suggest that both motor and somatosensory simulations are flexibly regulated to support simulations congruent with our sensorimotor experience and goals and suppress or separate the influence of those that are not. These regulatory mechanisms are frequently revealed by cases of brain injury but can also be employed to facilitate sensorimotor rehabilitation. Copyright © 2015. Published by Elsevier Ltd.
... In addition, emotionally mediated synaesthesia (Ward, 2004;Hochel et al., 2009), mirror-touch (Blakemore, Bristow, Bird, Frith, and Ward, 2005;Banissy and Ward, 2007;Banissy, Cohen Kadosh, et al., 2009;Banissy et al., 2011;Holle, Banissy, Wright, Bowling, and Ward, 2011), mirror-pain (Fitzgibbon, Giummarra, Georgiou-Karistianis, Enticott, and Bradshaw, 2010;, and tactile-emotion are dependent on the development of emotion, empathy, and social cognitive processes (Fitzgibbon et al., 2010;Fitzgibbon, Enticott, Rich, et al., 2012) that could not have existed as such in infancy. Nevertheless, the developmental basis of synaesthesia is unknown because of the absence of longitudinal and cross-sectional studies on the prevalence of particular types and kinds of synaesthesia across the lifespan. ...
Book
Synaesthesia is a fascinating cognitive phenomenon where one type of stimulation evokes the sensation of another. For example, synaesthetes might perceive colours when listening to music, or tastes in the mouth when reading words. This book provides an insight into the idiosyncratic nature of synaesthesia by exploring its relationships with other dimensions of individual differences. Many characteristics of linguistic-colour synaesthetes are covered including personality, temperament, intelligence, creativity, emotionality, attention, memory, imagination, colour perception, body lateralization and gender. Aleksandra Rogowska proposes that linguistic-colour synaesthesia can be considered as an abstract form of a continuous variable in the broader context of cross- and intra-modal associations. There has been a resurgence of interest in synaesthesia and this book will appeal to students and scientists of psychology, cognitive science and social science, and to those who are fascinated by unusual states of mind.
... One possible explanation is that vicarious pain is semantically stronger than vicarious touch, implying higher body ownership, and therefore, the neural activity associated with it would be less sensitive to illusory changes in body ownership elicited by the VHI. This idea is in line with the observation that vicarious pain is perceived as more intense than other vicarious somatosensations (Holle, Banissy, et al. 2011;Fusaro et al. 2016;Fusaro et al. 2019). ...
Article
Full-text available
Fundamental human feelings such as body ownership (“this” body is “my” body) and vicariousness (first-person-like experience of events occurring to others) are based on multisensory integration. Behavioral links between body ownership and vicariousness have been shown, but the neural underpinnings remain largely unexplored. To fill this gap, we investigated the neural effects of altered body ownership on vicarious somatosensation. While recording functional brain imaging data, first, we altered participants’ body ownership by robotically delivering tactile stimulations (“tactile” stroking) in synchrony or not with videos of a virtual hand being brushed (“visual” stroking). Then, we manipulated vicarious somatosensation by showing videos of the virtual hand being touched by a syringe’s plunger (touch) or needle (pain). Only after the alteration of body ownership (synchronous visuo-tactile stroking) and specifically during late epochs of vicarious somatosensation, vicarious pain was associated with lower activation in premotor and anterior cingulate cortices with respect to vicarious touch. At the methodological level, the present study highlights the importance of the neural response’s temporal evolution. At the theoretical level, it shows that the higher-level (cognitive) impact of a lower-level (sensory) body-related processing (visuo-tactile) is not limited to body ownership but also extends to other psychological body-related domains, such as vicarious somatosensation.
... rectangular geometrical objects [24]) and the pain neural network also responds to noxious stimuli applied to objects (e.g. a tomato [63]). Experiments conducted in mirror-touch synesthetes demonstrate that they also experience moderate tactile sensation during the observation of dummy body parts or objects being touched [64]. Altogether, these observations suggest that the mirroring system does not work in a pure body-specific way. ...
Article
Background: The observation of conspecifics influences our bodily perceptions and actions: Contagious yawning, contagious itching, or empathy for pain, are all examples of mechanisms based on resonance between our own body and others. While there is evidence for the involvement of the mirror neuron system in the processing of motor, auditory and tactile information, it has not yet been associated with the perception of self-motion.
... Image series of human and of wooden hands were presented. Given the observation that non-human agents engage simulation processes to a lesser extent (Beck et al., 2013; Holle et al., 2011; Streltsova & McCleery, 2012; Tai et al., 2004; Tsai & Brass, 2007), we expected congruency differences to diminish when the observed hand is a wooden hand. While a congruency effect for human hands only would indeed be the most straightforward result, any interaction of animacy and congruency would suggest that the interaction of action-based touch observation and felt touch is effector-specific. ...
Article
Full-text available
Action observation leads to a representation of both the motor aspect of an observed action (motor simulation) and its somatosensory consequences (action-based somatosensory simulation) in the observer's brain. In the current EEG-study, we investigated the neuronal interplay of action-based somatosensory simulation and felt touch. We presented index or middle finger tapping movements of a human or a wooden hand, while simultaneously presenting 'tap-like' tactile sensations to either the corresponding or non-corresponding fingertip of the participant. We focused on an early stage of somatosensory processing (P50, N100 and N140 SEPs) and on a later stage of higher-order processing (P3-complex). The results revealed an interaction effect of animacy and congruency in the early P50 SEP and an animacy effect in the N100/N140 SEPs. In the P3-complex, we found an interaction effect indicating that the influence of congruency was larger in the human than in the wooden hand. We argue that the P3-complex may reflect higher-order self-other distinction by signalling simulated action-based touch that does not match own tactile information. As such, the action-based somatosensory congruency paradigm might help understand higher-order social processes from a somatosensory point of view. © The Author (2015). Published by Oxford University Press. For Permissions, please email: journals.permissions@oup.com.
... Image series of human and of wooden hands were presented. Given the observation that non-human agents engage simulation processes to a lesser extent (Beck et al., 2013; Holle et al., 2011; Streltsova & McCleery, 2012; Tai et al., 2004; Tsai & Brass, 2007), we expected congruency differences to diminish when the observed hand is a wooden hand. While a congruency effect for human hands only would indeed be the most straightforward result, any interaction of animacy and congruency would suggest that the interaction of action-based touch observation and felt touch is effector-specific. ...
Article
Full-text available
Research on error observation has focused predominantly on situations in which individuals are passive observers of errors. In daily life, however, we are often jointly responsible for the mistakes of others. In the current study, we examined how information on agency is integrated in the error observation network. It was found that activation in the anterior insula but not in the posterior medial frontal cortex or lateral prefrontal cortex differentiates between observed errors for which we are partly responsible or not. Interestingly, the activation pattern of the AI was mirrored by feelings of guilt and shame. These results suggest that the anterior insula is crucially involved in evaluating the consequences of our actions for other persons. Consequently, this region may be thought of as critical in guiding social behavior.
... Finally, the videos depicted only hands without the rest of the body (e.g., head, body). Holle et al. (2011) demonstrated that the intensity of vicarious touch experiences is stronger when observing touch to real bodies compared with touch to dummy bodies, pictures of bodies, and disconnected dummy body parts. These results show that vicarious touch is not entirely bottom-up driven; also top-down information such as knowledge about dummy and real bodies can modulate the intensity of the vicarious experience. ...
Article
Full-text available
This study investigated the effects of observing pain and touch in others upon vicarious somatosensory experiences and the detection of subtle somatosensory stimuli. Furthermore, transcranial direct current stimulation (tDCS) was used to assess the role of the right temporoparietal junction (rTPJ), as this brain region has been suggested to be involved in perspective taking and self-other distinction. Undergraduates (N = 22) viewed videos depicting hands being touched, hands being pricked, and control scenes (same approaching movement as in the other video categories but without the painful/touching object), while experiencing vibrotactile stimuli themselves on the left, right, or both hands. Participants reported the location at which they felt a somatosensory stimulus. Vibrotactile stimuli and visual scenes were applied in a congruent or incongruent way. During three separate testing sessions, excitability of the rTPJ was modulated with tDCS (cathodal, anodal, or sham). We calculated the proportion of correct responses and false alarms (i.e., number of trials in which a vicarious somatosensory experience was reported congruent to the site of the visual information). Pain-related scenes facilitated the correct detection of tactile stimuli and augmented the number of vicarious somatosensory experiences compared with observing touch or control videos. Stimulation of the rTPJ had no reliable influence upon detection accuracy or the number of vicarious errors. This study indicates that the observation of pain-related scenes compared to the observation of touch or control videos increases the likelihood that a somatosensory stimulus is detected. Contrary to our expectations, the rTPJ did not modulate detection accuracy.
... These regions have significant effects on the modulation of pain inputs as well as on sensory affective, cognitive and discriminative phases of nociceptive processing [53]. The evidence also shows that hypothalamus has a major role in nociceptive processing, particularly in trigeminal nociceptive syndromes [54,55]. ...
Article
It is widely accepted that the spinal trigeminal nuclear complex, especially the subnucleus caudalis (Vc), receives input from orofacial structures. The neuropeptides orexin-A and -B are expressed in multiple neuronal systems. Orexin signaling has been implicated in pain-modulating system as well as learning and memory processes. Orexin 1 receptor (OX1R) has been reported in trigeminal nucleus caudalis. However, its roles in trigeminal pain modulation have not been elucidated so far. This study was designed to investigate the role of Vc OX1R in the modulation of orofacial pain as well as pain-induced learning and memory deficits. Orofacial pain was induced by subcutaneous injection of capsaicin in the right upper lip of the rats. OX1R agonist (orexin-A) and antagonist (SB-334867-A) were microinjected into Vc prior capsaicin administration. After recording nociceptive times, learning and memory was investigated using Morris water maze (MWM) test. The results indicated that, orexin-A (150 pM/rat) significantly reduced the nociceptive times, while SB334867-A (80 nM/rat) exaggerated nociceptive behavior in response to capsaicin injection. In MWM test, capsaicin-treated rats showed a significant learning and memory impairment. Moreover, SB-334867-A (80 nM/rat) significantly exaggerated learning and memory impairment in capsaicin-treated rats. However, administration of orexin-A (100 pM/rat) prevented learning and memory deficits. Taken together, these results indicate that Vc OX1R was at least in part involved in orofacial pain transmission and orexin-A has also a beneficial inhibitory effect on orofacial pain-induced deficits in abilities of spatial learning and memory.
... A number of studies have provided evidence for an on-line representation of body position in space e often called the body schema or postural schema (Head & Holmes, 1911;Medina & Coslett, 2010). In mirror touch synesthesia, one study examined the relationship between body position and mirror touch synesthesia, finding no effect of viewed face position or hand crossing on synesthetic percept intensity (Holle, Banissy, Wright, Bowling, & Ward, 2011). However, no studies have examined how the synesthete's body schema influences the mapping process from viewed touch to synesthetic percept. ...
Article
Individuals with mirror-touch synesthesia report feeling touch on their own body when seeing someone else being touched. We examined how the body schema – an on-line representation of body position in space – is involved in mapping touch from a viewed body to one’s own body. We showed 45 mirror-touch synesthetes videos of a hand being touched, varying the location of the viewed touch by hand (left, right), skin surface (palmar, dorsal) and finger (index, ring). Participant hand posture was either congruent or incongruent with the posture of the viewed hand. After seeing the video, participants were asked to report whether they felt touch on their own body and, if so, the intensity and location of their percepts. We found that participants reported more frequent and more veridical (i.e. felt at the same somatotopic location as the viewed touch) mirror-touch percepts on posturally congruent versus posturally incongruent trials. Furthermore, participant response patterns varied as a function of postural congruence. Some participants consistently felt sensations on the hand surface that was stimulated in the video – even if their hands were in the opposite posture. Other participants’ responses were modulated based on their own hand position, such that percepts were more likely to be felt on the upright, plausible hand surface in the posturally incongruent condition. These results provide evidence that mapping viewed touch to one’s own body involves an on-line representation of body position in space.
... For full details of the procedure used to measure mirror touch synaesthesia, see Ward et al. 82 . Participants watched short video clips 85 , including depictions of touch to a human (14 videos), touch to inanimate objects (dummies and a fan; 6 videos) and painful stimuli (e.g., injections; 6 videos). After each video, participants responded to questions by computer. ...
Article
Full-text available
In hypnotic responding, expectancies arising from imaginative suggestion drive striking experiential changes (e.g., hallucinations) - which are experienced as involuntary - according to a normally distributed and stable trait ability (hypnotisability). Such experiences can be triggered by implicit suggestion and occur outside the hypnotic context. In large sample studies (of 156, 404 and 353 participants), we report substantial relationships between hypnotisability and experimental measures of experiential change in mirror-sensory synaesthesia and the rubber hand illusion comparable to relationships between hypnotisability and individual hypnosis scale items. The control of phenomenology to meet expectancies arising from perceived task requirements can account for experiential change in psychological experiments.
... Finally, Banissy et al. (2009) also found that a large proportion of this group also reported other synaesthesia-like experiences, which is consistent with the finding that types of synaesthesia tend to co-occur (Simner et al., 2006). Further exploration of the characteristics of mirror-touch synaesthesia suggest that top-down processes may modulate the intensity of the mirror-touch synaesthetic experience (Holle et al., 2011). In a recent study, mirror-touch synaesthetes observed videos of touch, and reported whether a synaesthetic touch experience was elicited, and its intensity. ...
Article
Recent research suggests the observation or imagination of somatosensory stimulation in another (e.g., touch or pain) can induce a similar somatosensory experience in oneself. Some researchers have presented this experience as a type of synaesthesia, whereas others consider it an extreme experience of an otherwise normal perception. Here, we present an argument that these descriptions are not mutually exclusive. They may describe the extreme version of the normal process of understanding somatosensation in others. It becomes synaesthesia, however, when this process results in a conscious experience comparable to the observed person's state. We describe these experiences as 'mirror-sensory synaesthesia'; a type of synaesthesia identified by its distinct social component where the induced synaesthetic experience is a similar sensory experience to that perceived in another person. Through the operationalisation of this intriguing experience as synaesthesia, existing neurobiological models of synaesthesia can be used as a framework to explore how mechanisms may act upon social cognitive processes to produce conscious experiences similar to another person's observed state.
Article
Mirror-touch synaesthesia (MTS) is the conscious experience of tactile sensations induced by seeing someone else touched. This paper considers two different, although not mutually exclusive, theoretical explanations and, in the final section, considers the relation between MTS and other forms of synaesthesia and also other kinds of vicarious perception (e.g. contagious yawning). The Threshold Theory explains MTS in terms of hyper-activity within a mirror system for touch and/or pain. This offers a good account for some of the evidence (e.g. from fMRI) but fails to explain the whole pattern (e.g. structural brain differences outside of this system; performance on some tests of social cognition). The Self-Other Theory explains MTS in terms of disturbances in the ability to distinguish the self from others. This can be construed in terms of over-extension of the bodily self in to others, or as difficulties in the control of body-based self-other representations. In this account, MTS is a symptom of a broader cognitive profile. We suggest that meets the criteria for synaesthesia, despite the proximal causal mechanisms remaining largely unknown, and that the tendency to localise vicarious sensory experiences distinguishes it from other kinds of seemingly related phenomena (e.g. non-localised affective responses to observing pain).
Article
Full-text available
Individuals with mirror touch synaesthesia (MTS) experience touch on their own body when observing others being touched. A recent account proposes that such rare experiences could be linked to impairment in self-other representations. Here we tested participants with MTS on a battery of social cognition tests and found that compared to non-synaesthete controls, the MTS group showed impairment in imitation-inhibition but not in visual perspective taking or theory of mind. Although all of these socio-cognitive abilities rely on the control of self-other representations, they differ as to whether the self, or the other, should be preferentially represented. For imitation-inhibition, representations of the other should be inhibited and self-representations should be enhanced, whereas the opposite is true for visual perspective taking and theory of mind. These findings suggest that MTS is associated with a specific deficit in inhibiting representation of other individuals and shed light on the fractionability of processes underlying typical social cognition. Copyright © 2015 Elsevier Ltd. All rights reserved.
Article
Full-text available
Individuals with Mirror-Touch Synaesthesia (MTS) experience touch on their own bodies when observing another person being touched. Whilst somatosensory processing in MTS has been extensively investigated, the extent to which the remapping of observed touch on the synaesthete's body can also lead to changes in the mental representation of the self remains unknown. We adapted the experimental paradigm of the 'Enfacement Illusion' to quantify the changes in self-face recognition as a result of synaesthetic touch. MTS and control participants observed the face of an unfamiliar person being touched or not, without delivering touch on the participant's face. Changes in self-representation were quantified with a self-face recognition task, using 'morphed' images containing varying proportions of the participant's face and the face of the unfamiliar other. This task was administered before and after the exposure to the other face. While self-recognition performance for both groups was similar during pre-test, MTS individuals showed a significant change in self-recognition performance following the observation of touch delivered to the other face. Specifically, the images that participants had initially perceived as containing equal quantities of self and other became more likely to be recognised as the self after viewing the other being touched. These results suggest that observing touch on others not only elicits a conscious experience of touch in MTS, but also elicits a change in the mental representation of the self, blurring self-other boundaries. This is consistent with a multisensory account of the self, whereby integrated multisensory experiences maintain or update self-representations.
Article
In mirror-touch synaesthesia merely observing another person being touched will cause the observers to experience a touch sensation on their own body. The current study investigates whether this, normally a developmental condition, might be acquired following amputation. Twenty-eight amputees observed 67 videos of touch events and indicated a) whether the video elicited tactile sensations, b) where on the body this was located, c) the intensity of the sensation, and d) whether it was painful. Almost a third of amputees report a tactile sensation on their amputated phantom limb when watching someone else being touched. In this particular group the sensations tend to be localised on the phantom limb or stump, but are rarely reported elsewhere on the body. This occurs irrespective of the body part seen. The synaesthetic sensations were more intense when real bodies were observed relative to dummies or objects, and when the observed touch is mildly painful relative to non-painful. Although frequency, intensity and cause of phantom limb pain do not appear to determine whether an amputee will report mirror-touch sensations, those who do report it show greater empathic emotional reactivity. These results suggest that acquired synaesthesia may be linked with sensory loss, arising after amputation, and that highly empathic individuals could be predisposed to strengthening existing pathways between observed touch and felt touch.
Article
Full-text available
In so-called ‘mirror-touch synaesthesia’, observing touch to another person induces a subjective tactile sensation on the synaesthete’s own body. It has been suggested that this type of synaesthesia depends on increased activity in neural systems activated when observing touch to others. Here we report the first study on the prevalence of this variant of synaesthesia. Our findings indicate that this type of synaesthesia is just as common, if not more common than some of the more frequently studied varieties of synaesthesia such as grapheme-colour synaesthesia. Additionally, we examine behavioural correlates associated with the condition. In a second experiment, we show that synaesthetic experiences are not related to somatotopic cueing—a flash of light on an observed body part does not elicit the behavioural or subjective characteristics of synaesthesia. Finally, we propose a neurocognitive model to account for these characteristics and discuss the implications of our findings for general theories of synaesthesia.
Article
Full-text available
Simulation models of expression recognition contend that to understand another's facial expressions, individuals map the perceived expression onto the same sensorimotor representations that are active during the experience of the perceived emotion. To investigate this view, the present study examines facial expression and identity recognition abilities in a rare group of participants who show facilitated sensorimotor simulation (mirror-touch synesthetes). Mirror-touch synesthetes experience touch on their own body when observing touch to another person. These experiences have been linked to heightened sensorimotor simulation in the shared-touch network (brain regions active during the passive observation and experience of touch). Mirror-touch synesthetes outperformed nonsynesthetic participants on measures of facial expression recognition, but not on control measures of face memory or facial identity perception. These findings imply a role for sensorimotor simulation processes in the recognition of facial affect, but not facial identity.
Article
Full-text available
Social interactions are influenced by the perception of others as similar or dissimilar to the self. Such judgements could depend on physical and semantic characteristics, such as membership in an ethnic or political group. In the present study we tested whether social representations of the self and of others could affect the perception of touch. To this aim, we assessed tactile perception on the face when subjects observed a face being touched by fingers. In different conditions we manipulated the identity of the shown face. In a first experiment, Caucasian and Maghrebian participants viewed a face belonging either to their own or to a different ethnic group; in a second experiment, Liberal and Conservative politically active participants viewed faces of politicians belonging to their own or to the opposite political party. The results showed that viewing a touched face most strongly enhanced the perception of touch on the observer's face when the observed face belonged to his/her own ethnic or political group.
Article
Full-text available
We show that the affective experience of touch and the sight of touch can be modulated by cognition, and investigate in an fMRI study where top-down cognitive modulations of bottom-up somatosensory and visual processing of touch and its affective value occur in the human brain. The cognitive modulation was produced by word labels, ‘Rich moisturizing cream’ or ‘Basic cream’, while cream was being applied to the forearm, or was seen being applied to a forearm. The subjective pleasantness and richness were modulated by the word labels, as were the fMRI activations to touch in parietal cortex area 7, the insula and ventral striatum. The cognitive labels influenced the activations to the sight of touch and also the correlations with pleasantness in the pregenual cingulate/orbitofrontal cortex and ventral striatum. Further evidence of how the orbitofrontal cortex is involved in affective aspects of touch was that touch to the forearm [which has C fiber Touch (CT) afferents sensitive to light touch] compared with touch to the glabrous skin of the hand (which does not) revealed activation in the mid-orbitofrontal cortex. This is of interest as previous studies have suggested that the CT system is important in affiliative caress-like touch between individuals.
Article
Full-text available
Theories of embodied cognition propose that recognizing facial expressions requires visual processing followed by simulation of the somatovisceral responses associated with the perceived expression. To test this proposal, we targeted the right occipital face area (rOFA) and the face region of right somatosensory cortex (rSC) with repetitive transcranial magnetic stimulation (rTMS) while participants discriminated facial expressions. rTMS selectively impaired discrimination of facial expressions at both sites but had no effect on a matched face identity task. Site specificity within the rSC was demonstrated by targeting rTMS at the face and finger regions while participants performed the expression discrimination task. rTMS targeted at the face region impaired task performance relative to rTMS targeted at the finger region. To establish the temporal course of visual and somatosensory contributions to expression processing, double-pulse TMS was delivered at different times to rOFA and rSC during expression discrimination. Accuracy dropped when pulses were delivered at 60-100 ms at rOFA and at 100-140 and 130-170 ms at rSC. These sequential impairments at rOFA and rSC support embodied accounts of expression recognition as well as hierarchical models of face processing. The results also demonstrate that nonvisual cortical areas contribute during early stages of expression processing.
Article
Full-text available
It is well known that you cannot tickle yourself. Here, we discuss the proposal that such attenuation of self-produced tactile stimulation is due to the sensory predictions made by an internal forward model of the motor system. A forward model predicts the sensory consequences of a movement based on the motor command. When a movement is self-produced, its sensory consequences can be accurately predicted, and this prediction can be used to attenuate the sensory effects of the movement. Studies are reviewed that demonstrate that as the discrepancy between predicted and actual sensory feedback increases during self-produced tactile stimulation there is a concomitant decrease in the level of sensory attenuation and an increase in tickliness. Functional neuroimaging studies have demonstrated that this sensory attenuation might be mediated by somatosensory cortex and anterior cingulate cortex: these areas are activated less by a self-produced tactile stimulus than by the same stimulus when it is externally produced. Furthermore, evidence suggests that the cerebellum might be involved in generating the prediction of the sensory consequences of movement. Finally, recent evidence suggests that this predictive mechanism is abnormal in patients with auditory hallucinations and/or passivity experiences.
Article
Full-text available
Rice University The visual modality typically dominates over our other senses. Here we show that after inducing an extreme conflict in the left hand between vision of touch (present) and the feeling of touch (absent), sensitivity to touch increases for several minutes after the conflict. Transcranial magnetic stimulation of the posterior parietal cortex after this conflict not only eliminated the enduring visual enhancement of touch, but also impaired normal tactile perception. This latter finding demonstrates a direct role of the parietal lobe in modulating tactile perception as a result of the conflict between these senses. These results provide evidence for visual-to-tactile perceptual modulation and demonstrate effects of illusory vision of touch on touch perception through a long-lasting modulatory process in the posterior parietal cortex.
Article
Full-text available
In this study, we describe a new form of synaesthesia in which visual perception of touch elicits conscious tactile experiences in the perceiver. We describe a female subject (C) for whom the observation of another person being touched is experienced as tactile stimulation on the equivalent part of C's own body. Apart from this clearly abnormal synesthetic experience, C is healthy and normal in every other way. In this study, we investigate whether C's 'mirrored touch' synesthetic experience is caused by overactivity in the neural system that responds to the observation of touch. A functional MRI experiment was designed to investigate the neural system involved in the perception of touch in a group of 12 non-synesthetic control subjects and in C. We investigated neural activity to the observation of touch to a human face or neck compared with the observation of touch to equivalent regions on an object. Furthermore, to investigate the somatosensory topography of the activations during observation of touch, we compared activations when observing a human face or neck being touched with activations when the subjects themselves were touched on their own face or neck. The results demonstrated that the somatosensory cortex was activated in the non-synesthetic subjects by the mere observation of touch and that this activation was somatotopically organized such that observation of touch to the face activated the head area of primary somatosensory cortex, whereas observation of touch to the neck did not. Moreover, in non-synesthetic subjects, the brain's mirror system-comprising premotor cortex, superior temporal sulcus and parietal cortex-was activated by the observation of touch to another human more than to an object. C's activation patterns differed in three ways from those of the non-synesthetic controls. First, activations in the somatosensory cortex were significantly higher in C when she observed touch. Secondly, an area in left premotor cortex was activated in C to a greater extent than in the non-synesthetic group. Thirdly, the anterior insula cortex bilaterally was activated in C, but there was no evidence of such activation in the non-synesthetic group. The results suggest that, in C, the mirror system for touch is overactive, above the threshold for conscious tactile perception.
Article
Full-text available
The neural processes underlying empathy are a subject of intense interest within the social neurosciences. However, very little is known about how brain empathic responses are modulated by the affective link between individuals. We show here that empathic responses are modulated by learned preferences, a result consistent with economic models of social preferences. We engaged male and female volunteers in an economic game, in which two confederates played fairly or unfairly, and then measured brain activity with functional magnetic resonance imaging while these same volunteers observed the confederates receiving pain. Both sexes exhibited empathy-related activation in pain-related brain areas (fronto-insular and anterior cingulate cortices) towards fair players. However, these empathy-related responses were significantly reduced in males when observing an unfair person receiving pain. This effect was accompanied by increased activation in reward-related areas, correlated with an expressed desire for revenge. We conclude that in men (at least) empathic responses are shaped by valuation of other people's social behaviour, such that they empathize with fair opponents while favouring the physical punishment of unfair opponents, a finding that echoes recent evidence for altruistic punishment.
Article
Full-text available
Whether observation of distress in others leads to empathic concern and altruistic motivation, or to personal distress and egoistic motivation, seems to depend upon the capacity for self-other differentiation and cognitive appraisal. In this experiment, behavioral measures and event-related functional magnetic resonance imaging were used to investigate the effects of perspective-taking and cognitive appraisal while participants observed the facial expression of pain resulting from medical treatment. Video clips showing the faces of patients were presented either with the instruction to imagine the feelings of the patient ("imagine other") or to imagine oneself to be in the patient's situation ("imagine self"). Cognitive appraisal was manipulated by providing information that the medical treatment had or had not been successful. Behavioral measures demonstrated that perspective-taking and treatment effectiveness instructions affected participants' affective responses to the observed pain. Hemodynamic changes were detected in the insular cortices, anterior medial cingulate cortex (aMCC), amygdala, and in visual areas including the fusiform gyrus. Graded responses related to the perspective-taking instructions were observed in middle insula, aMCC, medial and lateral premotor areas, and selectively in left and right parietal cortices. Treatment effectiveness resulted in signal changes in the perigenual anterior cingulate cortex, in the ventromedial orbito-frontal cortex, in the right lateral middle frontal gyrus, and in the cerebellum. These findings support the view that humans' responses to the pain of others can be modulated by cognitive and motivational processes, which influence whether observing a conspecific in need of help will result in empathic concern, an important instigator for helping behavior.
Article
Full-text available
Diffusion tensor imaging allowed us to validate for the first time the hypothesis that hyperconnectivity causes the added sensations in synesthesia. Grapheme-color synesthetes (n = 18), who experience specific colors with particular letters or numbers (for example, 'R is sky blue'), showed greater anisotropic diffusion compared with matched controls. Greater anisotropic diffusion indicates more coherent white matter. Anisotropy furthermore differentiated subtypes of grapheme-color synesthesia. Greater connectivity in the inferior temporal cortex was particularly strong for synesthetes who see synesthetic color in the outside world ('projectors') as compared with synesthetes who see the color in their 'mind's eye' only ('associators'). In contrast, greater connectivity (as compared with non-synesthetes) in the superior parietal or frontal cortex did not differentiate between subtypes of synesthesia. In conclusion, we found evidence that increased structural connectivity is associated with the presence of grapheme-color synesthesia, and has a role in the subjective nature of synesthetic color experience.
Article
Full-text available
Watching another person being touched activates a similar neural circuit to actual touch and, for some people with 'mirror-touch' synesthesia, can produce a felt tactile sensation on their own body. In this study, we provide evidence for the existence of this type of synesthesia and show that it correlates with heightened empathic ability. This is consistent with the notion that we empathize with others through a process of simulation.
Article
Full-text available
Observing touch on another person's body activates brain regions involved in tactile perception, even when the observer's body is not directly stimulated. Previous work has shown that in some synaesthetes, this effect induces a sensation of being touched. The present study shows that if perceptual thresholds are experimentally manipulated, viewing touch can modulate tactile experience in nonsynaesthetes as well. When observers saw a face being touched by hands, rather than a face being merely approached by hands, they demonstrated enhanced detection of subthreshold tactile stimuli on their own faces. This effect was specific to observing touch on a body part, and was not found for touch on a nonbodily stimulus, namely, a picture of a house. In addition, the effect was stronger when subjects viewed their own faces rather than another person's face. Thus, observing touch can activate the tactile system, and if perceptual thresholds are manipulated, such activation can result in a behavioral effect in nonsynaesthetes. The effect is maximum if the observed body matches the observer's body.
Article
Our ability to recognize the emotions of others is a crucial feature of human social cognition. Functional neuroimaging studies indicate that activity in sensorimotor cortices is evoked during the perception of emotion. In the visual domain, right somatosensory cortex activity has been shown to be critical for facial emotion recognition. However, the importance of sensorimotor representations in modalities outside of vision remains unknown. Here we use continuous theta-burst transcranial magnetic stimulation (cTBS) to investigate whether neural activity in the right postcentral gyrus (rPoG) and right lateral premotor cortex (rPM) is involved in nonverbal auditory emotion recognition. Three groups of participants completed same-different tasks on auditory stimuli, discriminating between the emotion expressed and the speakers' identities, before and following cTBS targeted at rPoG, rPM, or the vertex (control site). A task-selective deficit in auditory emotion discrimination was observed. Stimulation to rPoG and rPM resulted in a disruption of participants' abilities to discriminate emotion, but not identity, from vocal signals. These findings suggest that sensorimotor activity may be a modality-independent mechanism which aids emotion discrimination.
Article
Previous findings imply that synaesthetic experience may have consequences for sensory processing of stimuli that do not themselves trigger synaesthesia. For example, synaesthetes who experience colour show enhanced perceptual processing of colour compared to non-synaesthetes. This study aimed to investigate whether enhanced perceptual processing was a core property of synaesthesia by contrasting tactile and colour sensitivity in synaesthetes who experience either colour, touch, or both touch and colour as evoked sensations. For comparison the performance of non-synaesthetic control subjects was also assessed. There was a relationship between the modality of synaesthetic experience and the modality of sensory enhancement. Synaesthetes who experience colour have enhanced colour sensitivity and synaesthetes who experience touch have enhanced tactile sensitivity. These findings suggest the possibility that a hyper-sensitive concurrent perceptual system is a general property of synaesthesia and are discussed in relation to theories of the condition.
Article
Synesthesia, a neurological condition affecting between 0.05%-1% of the population, is characterized by anomalous sensory perception and associated alterations in cognitive function due to interference from synesthetic percepts. A stimulus in one sensory modality triggers an automatic, consistent response in either another modality or a different aspect of the same modality. Familiality studies show evidence of a strong genetic predisposition; whereas initial pedigree analyses supported a single-gene X-linked dominant mode of inheritance with a skewed F:M ratio and a notable absence of male-to-male transmission, subsequent analyses in larger samples indicated that the mode of inheritance was likely to be more complex. Here, we report the results of a whole-genome linkage scan for auditory-visual synesthesia with 410 microsatellite markers at 9.05 cM density in 43 multiplex families (n = 196) with potential candidate regions fine-mapped at 5 cM density. Using NPL and HLOD analysis, we identified four candidate regions. Significant linkage at the genome-wide level was detected to chromosome 2q24 (HLOD = 3.025, empirical genome-wide p = 0.047). Suggestive linkage was found to chromosomes 5q33, 6p12, and 12p12. No support was found for linkage to the X chromosome; furthermore, we have identified two confirmed cases of male-to-male transmission of synesthesia. Our results demonstrate that auditory-visual synesthesia is likely to be an oligogenic disorder subject to multiple modes of inheritance and locus heterogeneity. This study comprises a significant step toward identifying the genetic substrates underlying synesthesia, with important implications for our understanding of the role of genes in human cognition and perception.
Article
Parietal cortex contributes to body representations by integrating visual and somatosensory inputs. Because mirror neurons in ventral premotor and parietal cortices represent visual images of others' actions on the intrinsic motor representation of the self, this matching system may play important roles in recognizing actions performed by others. However, where and how the brain represents others' bodies and correlates self and other body representations remain unclear. We expected that a population of visuotactile neurons in simian parietal cortex would represent not only own but others' body parts. We first searched for parietal visuotactile bimodal neurons in the ventral intraparietal area and area 7b of monkeys, and then examined the activity of these neurons while monkeys were observing visual or tactile stimuli placed on the experimenter's body parts. Some bimodal neurons with receptive fields (RFs) anchored on the monkey's body exhibited visual responses matched to corresponding body parts of the experimenter, and visual RFs near that body part existed in the peripersonal space within approximately 30 cm from the body surface. These findings suggest that the brain could use self representation as a reference for perception of others' body parts in parietal cortex. These neurons may contribute to spatial matching between the bodies of the self and others in both action recognition and imitation.
Article
Although lesion and functional imaging studies have broadly implicated the right hemisphere in the recognition of emotion, neither the underlying processes nor the precise anatomical correlates are well understood. We addressed these two issues in a quantitative study of 108 subjects with focal brain lesions, using three different tasks that assessed the recognition and naming of six basic emotions from facial expressions. Lesions were analyzed as a function of task performance by coregistration in a common brain space, and statistical analyses of their joint volumetric density revealed specific regions in which damage was significantly associated with impairment. We show that recognizing emotions from visually presented facial expressions requires right somatosensory-related cortices. The findings are consistent with the idea that we recognize another individual's emotional state by internally generating somatosensory representations that simulate how the other individual would feel when displaying a certain facial expression. Follow-up experiments revealed that conceptual knowledge and knowledge of the name of the emotion draw on neuroanatomically separable systems. Right somatosensory-related cortices thus constitute an additional critical component that functions together with structures such as the amygdala and right visual cortices in retrieving socially relevant information from faces.
Article
Watching the movie scene in which a tarantula crawls on James Bond's chest can make us literally shiver--as if the spider crawled on our own chest. What neural mechanisms are responsible for this "tactile empathy"? The observation of the actions of others activates the premotor cortex normally involved in the execution of the same actions. If a similar mechanism applies to the sight of touch, movies depicting touch should automatically activate the somatosensory cortex of the observer. Here we found using fMRI that the secondary but not the primary somatosensory cortex is activated both when the participants were touched and when they observed someone or something else getting touched by objects. The neural mechanisms enabling our own sensation of touch may therefore be a window also to our understanding of touch.
Article
When we look at our hands, we immediately know that they are part of our own body. This feeling of ownership of our limbs is a fundamental aspect of self-consciousness. We have studied the neuronal counterparts of this experience. A perceptual illusion was used to manipulate feelings of ownership of a rubber hand presented in front of healthy subjects while brain activity was measured by functional magnetic resonance imaging. The neural activity in the premotor cortex reflected the feeling of ownership of the hand. This suggests that multisensory integration in the premotor cortex provides a mechanism for bodily self-attribution.
Article
Previous research on multisensory integration has demonstrated that viewing the stimulated body part enhances discrimination ability. Participants in this experiment watched a video showing a hand being touched by a stick and a second video showing the stick touching the space beneath the hand. Sensory thresholds of the index fingers were tested with von Frey filaments. We found significant enhancements of the sensory threshold after showing the video with the touched hand but not after showing the video with no touch of the hand. This enhancement was specific for the index finger shown in the video. The results link the visuotactile enhancement of this study to the observation of touch rather than to the simple depiction of the body part.
Article
When the synaesthete, J, is shown black graphemes, in addition to perceiving the black digits or letters she also experiences highly specific colours that overlay the graphemes (e.g., 5 is pink, S is green). We used ambiguous graphemes in a Stroop-type task to show that the exact same forms (e.g., 5) can elicit different synaesthetic colours depending on whether they are interpreted as digits or letters. J was shown strings of black digits (e.g., 3 4 5 6 7) or words (e.g., M U S I C for 1 sec. All but one of the graphemes then disappeared and the remaining grapheme changed to a colour that J had to name as quickly as possible. The key trials involved coloured graphemes that were ambiguous (e.g., the 5 in the strings above could be interpreted either as a digit or as a letter). On congruent trials, the colour of the ambiguous target grapheme was the same as J's photism for the digit or letter interpretations of the grapheme. On incongruent trials, the colours of the ambiguous target graphemes were different than the colours of J's photisms for the digit or letter interpretations of the graphemes. On digit-context incongruent trials, the ambiguous graphemes were presented in J's colour for the letter-interpretations of the graphemes, whereas on letter-context incongruent trials, the ambiguous graphemes were presented in J's colours for the digit-interpretations of the graphemes. Thus the same ambiguous grapheme (e.g., a pink 5) served as a congruent stimulus in one context and an incongruent stimulus in another context. J's response times showed that ambiguous graphemes elicited different photisms depending on whether they were interpreted as digits or letters. This finding suggests that it is not the form but the meaning of graphemes (whether they are interpreted as digits or letters) that determines the colours of synaesthetic photisms.
Article
In an early description of the mu rhythm, Gastaut and Bert [Gastaut, H. J., & Bert, J. (1954). EEG changes during cinematographic presentation. Clinical Neurophysiology, 6, 433-444] noted that it was blocked when an individual identified himself with an active person on the screen, suggesting that it may be modulated by the degree to which the individual can relate to the observed action. Additionally, multiple recent studies suggest that the mirror neurons system (MNS) is impaired in individuals with autism spectrum disorders (ASD), which may affect their ability to relate to others. The current study aimed to investigate MNS sensitivity by examining mu suppression to familiarity, i.e., the degree to which the observer is able to identify with the actor on the screen by using familiar versus unfamiliar actors. The participants viewed four 80s videos that included: (1) stranger: an unfamiliar hand performing a grasping action; (2) familiar: the child's guardian or sibling's hand performing the same action; (3) own: the participant's own hand performing the same action; (4) bouncing balls: two balls moving vertically toward and away from each other. The study revealed that mu suppression was sensitive to degree of familiarity. Both typically developing participants and those with ASD showed greater suppression to familiar hands compared to those of strangers. These findings suggest that the MNS responds to observed actions in individuals with ASD, but only when individuals can identify in some personal way with the stimuli.
Article
Previous studies have shown a shared neural circuitry in the somatosensory cortices for the experience of one's own body being touched and the sight of intentional touch. Using functional magnetic resonance imaging (fMRI), the present study aimed to elucidate whether the activation of a visuotactile mirroring mechanism during touch observation applies to the sight of any touch, that is, whether it is independent of the intentionality of observed touching agent. During fMRI scanning, healthy participants viewed video clips depicting a touch that was intentional or accidental, and occurring between animate or inanimate objects. Analyses showed equal overlapping activation for all the touch observation conditions and the experience of one's own body being touched in the bilateral secondary somatosensory cortex (SII), left inferior parietal lobule (IPL)/supramarginal gyrus, bilateral temporal-occipital junction, and left precentral gyrus. A significant difference between the sight of an intentional touch, compared to an accidental touch, was found in the left primary somatosensory cortex (SI/Brodmann's area [BA] 2). Interestingly, activation in SI/BA 2 significantly correlated with the degree of intentionality of the observed touch stimuli as rated by participants. Our findings show that activation of a visuotactile mirroring mechanism for touch observation might underpin an abstract notion of touch, whereas activation in SI might reflect a human tendency to "resonate" more with a present or assumed intentional touching agent.
(in press) Superior facial expression, but not identity recognition, in mirror-touch synaesthesia Suppressing sensory-motor activity modulates the discrimination of auditory emotions but not speaker identity
  • M J Banissy
  • L Garrido
  • F Kusnir
  • B Duchaine
  • V Walsh
  • J Ward
  • M J Banissy
  • D Sauter
  • J Ward
  • J E Warren
  • V Walsh
  • S K Scott
Banissy, M. J., Garrido, L., Kusnir, F., Duchaine, B., Walsh, V., & Ward, J. (in press). Superior facial expression, but not identity recognition, in mirror-touch synaesthesia. Journal of Neuroscience. Banissy, M. J., Sauter, D., Ward, J., Warren, J. E., Walsh, V., & Scott, S. K. (2010). Suppressing sensory-motor activity modulates the discrimination of auditory emotions but not speaker identity. Journal of Neuroscience, 30, 13552–13557.