This introduction gives an analysis of the available scientific writings on synesthesia. It analysis prevalence, reality and features of this disorder. It also gives a summary of main theories on synesthesia and also an overview of psychophysical studies which gives in-depth knowledge on about Mirror-touch synesthesia. It also the summary of broader traits associated with synesthesia. The main goal of this inquiry is to clarify general personality traits and dissimilarities in social perception connected to this form of synesthesia and how this type of disorder is linked to empathy.
Prevalence and classification Mirror-touch synesthesia(MTS) is a disorder characterized by undergoing sensations on individual’s body when seeing touch applied to a different individual. The first acknowledged case of this type of synesthesia by authors (Blakemore, Bristow, Bird, Frith and Ward,2005).
The prevalence of individuals who qualified for objective necessities for this type of synesthesia is projected to be 1.6 percent of the population (Banissy, Kadosh, Maus, Walsh, and Ward, 2009). This specific disorder can be categorized into 2 groups grounded on the spatial mapping of the synesthetic tactile feelings relative to witnessed touch.
The Specular form entails feeling a synesthetic touch on the reverse side to the witnessed touch Tests of authenticity The reality of mirror-touch synesthesia can be proven through a mirror-touch Stroop method; this is a test established by (Banissy and Ward, 2007).
In this particular test partakers are required to report the area where they experienced the touch (Right, left, both sides, and no touch) delivered by tappers held to the face while observing a series of videos presenting an object and somebody also being touched (on the right, left, both sides or touch).
For mirror-touch synesthetic, synesthetic touch can either be incongruent or congruent with the actual touch. For example, if the participant is a specular mirror-touch synesthetic and the individual in the video is touched on the right cheek, he/she will feel a synesthetic touch on the left side. Theories of mirror-touch synesthesia and supporting evidence In a recent research carried out (Holle, Banissy and Ward,2013) support was given for the existence of cortical hyperactivity in the mirror-touch synesthesia. In fMRI research, a group of MTS and a group of controls were given with a various of videos presenting no-touch or touch to a face, an object or a dummy.
The researchers report mirror-touch synesthesia to be connected with the hyper-excitability both in primary (SI) and the secondary somatosensory cortex (SII) in reaction to videos presenting touch to a physical face but they recommended SII to take the main role in this type of synesthesia as this area was activated by real touch, which also connected with tactile intensity ratings and also showed amplified grey matter density in Mirror-touch synesthesia. Moreover, voxel-based morphometry (VBM) examination used by (Holle et al., 2013) exposed structural dissimilarities connected to mirror-touch synesthesia in brain areas spreading past the somatosensory cortices.
The researches also found decreased grey matter volume in medial prefrontal cortex (mPFC), the right temporal-parietal junction (TPJ), and increased white and grey matter density in the right temporal pole. According to (Santiesteban, Banissy, Catmur, and Bird, 2012), these areas have been previously connected to perspective taking and self-other monitoring (Arzy, Thut, Mohr, Michel, and Blanke, 2006) leading the authors (Banissy and Ward ,2013) to form a theory that hyper-excitability in the mirror neuron network system witnessed in mirror-touch synesthesia may perhaps be facilitated by abnormal self-other distinction replicated in the above-mentioned dissimilarities in Mpfc and rTPI found in MTS.
Mirror-touch synesthesia has been linked with deficits connected to inhibiting the viewpoint of another individual. In the latest study by (Santiesteban, Bird, Tew, Cioffi and Banissy,2015) engaged a finger lifting model (Brass et al., 2005), which called for lifting the middle or index finger which incongruent or congruent with the act of stimulus hand showed on the screen. The performance on this job is measured with congruency result whereby partakers are generally quicker and more exact on congruent trials when matched with the incongruent ones. The researchers reported that MTS have insufficiencies in overpowering the depiction of the other individual, which is established in the tendency to over- copy observed actions The authors (Bufalari, Porciello, and Aglioti, 2015) clarifies the MTSs are employing the two models.
Mirror Touch Synesthetic (MTSs) experience touch while they notice others getting touched. According to the writers, two complementary hypothetical structures, the Threshold Concept and Self-Other Theory, elucidate Mirror Touch Synesthesia (MTS). Grounded on the behavioral proof that in MTSs the ordinary observation of touch is adequate to cause self-other assimilation (i.e., self-representation alterations), a state that in non-MTSs just provokes self- other sharing, and on the rTPJ functional changes in MTS, we claim that MTS may originate from abnormally malleable self-representation and abnormal multi-sensory integrative mechanisms.
Broader traits associated with mirror-touch synesthesia Apart from discrepancies connected to inhibiting the viewpoint of another person and greater plastic of body representation MTS have been related to other traits, for instance, greater empathy relative to control partakers also GCS (Banissy and Ward, 2007). Precisely, MTS was related to greater emotional reactivity weighed with Empathy Quotient as (Baron-Cohen, and Wheelwright, 2004) put it.
They were as well found to hold greater emotion recognition capability compared to the non-synesthetic person on a task which be made up of matching adjectives depicting an emotional condition with a picture showing a person with a facial look which best symbolized that label (Banissy et al., 2011). These results are corresponding with the simulation interpretations of social cognition which propose that activating collective brain parts both when executing and noticing actions,but also when experiencing and observing emotions facilitates our ability to empathise and understand others (Gallese, Keysers, and Rizzolatti, 2004; Gallese, 2006; Keysers and Gazzola, 2006).
These results are also consistence with prior work indicating intensified activity in the mirror-neuron network in this type of synaesthesia (Holle, Banissy, Ward, 2013). The authors (Meier, Lunke, and Rothen,2015) examine how Threshold Concept and the Self-Other Theory matches the synesthesia theories. The threshold concept of mirror-touch is grounded on the notion that the level of action in somatosensory miror system crosses a threshold of consciousness for some individuals but not others. As usual forms of synesthesia are associated with networks between distinct brain structures rather than depending on a single primary subsystem (as the mirror system), an instant overview is not justified The Self-Other Philosophy is based on the supposition that aberrant self-other depictions generate mirror-touch.
Precisely, difficulties in differentiating the self from a different individual as the basis of agency fom the source of the experiences. In synesthesia, the latter would denote to complications in differentiating between synesthetic and physical experience. To conclude, the debate of mirror-touch in connection with synesthesia is interesting as it improves the definitional measures. Co-occurrence of the mirror-touch feeling with other types of synesthesia is remarkable and may point out that mirror-touch synesthesia is a distinctive type of synesthesia (Banissy, 2013). Nevertheless, we propose that it co-occurs with other types of synesthesia as a by-product. (Banissy et al., 2012, 2013)