RESUMEN
The acquisition of reading modifies areas of the brain associated with vision and with language, in addition to their connections. These changes enable reciprocal translation between orthography and the sounds and meaning of words. Individual variability in the pre-existing cerebral substrate contributes to the range of eventual reading abilities, extending to atypical developmental patterns, including dyslexia and reading-related synaesthesias. The present study is devoted to the little-studied but highly informative ticker-tape synaesthesia, in which speech perception triggers the vivid and irrepressible perception of words in their written form in the mind's eye. We scanned a group of 17 synaesthetes and 17 matched controls with functional MRI, while they listened to spoken sentences, words, numbers or pseudowords (Experiment 1), viewed images and written words (Experiment 2) or were at rest (Experiment 3). First, we found direct correlates of the ticker-tape synaesthesia phenomenon: during speech perception, as ticker-tape synaesthesia was active, synaesthetes showed over-activation of left perisylvian regions supporting phonology and of the occipitotemporal visual word form area, where orthography is represented. Second, we provided support to the hypothesis that ticker-tape synaesthesia results from atypical relationships between spoken and written language processing: the ticker-tape synaesthesia-related regions overlap closely with cortices activated during reading, and the overlap of speech-related and reading-related areas is larger in synaesthetes than in controls. Furthermore, the regions over-activated in ticker-tape synaesthesia overlap with regions under-activated in dyslexia. Third, during the resting state (i.e. in the absence of current ticker-tape synaesthesia), synaesthetes showed increased functional connectivity between left prefrontal and bilateral occipital regions. This pattern might reflect a lowered threshold for conscious access to visual mental contents and might imply a non-specific predisposition to all synaesthesias with a visual content. These data provide a rich and coherent account of ticker-tape synaesthesia as a non-detrimental developmental condition created by the interaction of reading acquisition with an atypical cerebral substrate.
Asunto(s)
Imagen por Resonancia Magnética , Lectura , Percepción del Habla , Sinestesia , Humanos , Masculino , Femenino , Adulto , Percepción del Habla/fisiología , Adulto Joven , Encéfalo/diagnóstico por imagen , Mapeo Encefálico/métodos , Persona de Mediana Edad , Habla/fisiología , Dislexia/fisiopatología , Dislexia/diagnóstico por imagenRESUMEN
Grapheme-color synesthesia is expected to provide a clue to solving the "binding problem" of visual features. Synesthetic research uses non-synesthetes as a control group and shows that synesthetes perform better with synesthetic color congruency, while non-synesthetes' performances do not. However, non-synesthetes also have certain grapheme-color associations. Therefore, this study examined whether non-synesthetes' grapheme-color associations improve their performance in a visual search task. The results indicated that non-synesthetes were significantly faster at detecting congruent targets with their grapheme-color associations, such as red for "A," blue for "B," and yellow for "C." However, the effect was not found in relation to numerical characters. This study has implications for future neuroscience and consciousness research regarding grapheme-color synesthesia.
Asunto(s)
Trastornos de la Percepción , Humanos , Sinestesia , Estimulación Luminosa/métodos , Percepción de Color , Reconocimiento Visual de ModelosRESUMEN
A long-standing issue concerning synesthesia is whether the trait is continuous or discontinuous with ordinary perception. Here, we found that a substantial proportion of non-synesthetes (>10 % out of >200 unselected participants) spontaneously became aware of their synesthesia by participating in an online survey that forced them to select colors for stimuli that evoke color sensations in synesthetes. Notably, the test-retest consistencies of color sensation in these non-synesthetes were comparable to those in self-claimed synesthetes, revealing their strong though latent synesthetic dispositions. The effect was absent or weak in a matched control survey that did not include the color-picking test. Therefore, the color-picking task likely provided the predisposed "borderline non-synesthetes" with an opportunity to dwell on their tendency toward synesthesia and allowed their subconscious sensations to become conscious ones. The finding suggests that the general population has a continuum of synesthetic disposition that encompasses both synesthetes and non-synesthetes.
Asunto(s)
Trastornos de la Percepción , Humanos , Sinestesia , Percepción de Color/fisiología , Sensación , Personalidad , Estimulación Luminosa , Reconocimiento Visual de Modelos/fisiologíaRESUMEN
The replication crisis has taught us to expect small-to-medium effects in psychological research. But this is based on effect sizes calculated over single variables. Mahalanobis D, the multivariate equivalent of Cohen's d, can enable very large group differences to emerge from a collection of small-to-medium effects (here, reanalysing multivariate datasets from synaesthetes and controls). The use of multivariate effect sizes is not a slight of hand but may instead be a truer reflection of the degree of psychological differences between people that has been largely underappreciated.
Asunto(s)
Cognición , Percepción de Color , Humanos , SinestesiaRESUMEN
Synaesthesia has been conceptualised as a joining of sensory experiences. Taking a holistic, embodied perspective, we investigate in this paper the role of action and emotion, testing hypotheses related to (1) changes to action-related qualities of a musical stimulus affect the resulting synaesthetic experience; (2) a comparable relationship exists between music, sensorimotor and emotional responses in synaesthetes and the general population; and (3) sensorimotor responses are more strongly associated with synaesthesia than emotion. 29 synaesthetes and 33 non-synaesthetes listened to 12 musical excerpts performed on a musical instrument they had first-hand experience playing, an instrument never played before, and a deadpan performance generated by notation software, i.e., a performance without expression. They evaluated the intensity of their experience of the music using a list of dimensions that relate to sensorimotor, emotional or synaesthetic sensations. Results demonstrated that the intensity of listeners' responses was most strongly influenced by whether or not music is performed by a human, more so than familiarity with a particular instrument. Furthermore, our findings reveal a shared relationship between emotional and sensorimotor responses among both synaesthetes and non-synaesthetes. Yet it was sensorimotor intensity that was shown to be fundamentally associated with the intensity of the synaesthetic response. Overall, the research argues for, and gives first evidence of a key role of action in shaping the experiences of music-colour synaesthesia.
Asunto(s)
Percepción de Color , Música , Humanos , Percepción de Color/fisiología , Color , Música/psicología , Estimulación Luminosa/métodos , Sinestesia , EmocionesRESUMEN
Intramodal and cross-modal perceptual grouping based on the spatial proximity and temporal closeness between multiple sensory stimuli, as an operational principle has built a coherent and meaningful representation of the multisensory event/object. To implement and investigate the cross-modal perceptual grouping, researchers have employed excellent paradigms of spatial/temporal ventriloquism and cross-modal dynamic capture and have revealed the conditional constraints as well as the functional facilitations among various correspondence of sensory properties, with featured behavioral evidence, computational framework as well as brain oscillation patterns. Typically, synesthetic correspondence as a special type of cross-modal correspondence can shape the efficiency and effect-size of cross-modal interaction. For example, factors such as pitch/loudness in the auditory dimension with size/brightness in the visual dimension could modulate the strength of the cross-modal temporal capture. The empirical behavioral findings, as well as psychophysical and neurophysiological evidence to address the cross-modal perceptual grouping and synesthetic correspondence, were summarized in this review. Finally, the potential applications (such as artificial synesthesia device) and how synesthetic correspondence interface with semantics (sensory linguistics), as well as the promising research questions in this field have been discussed.
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Encéfalo , Investigadores , Humanos , Sinestesia , SemánticaRESUMEN
Grapheme-color synesthetes experience color when seeing achromatic symbols. We examined whether similar neural mechanisms underlie color perception and synesthetic colors using magnetoencephalography. Classification models trained on neural activity from viewing colored stimuli could distinguish synesthetic color evoked by achromatic symbols after a delay of â¼100 ms. Our results provide an objective neural signature for synesthetic experience and temporal evidence consistent with higher-level processing in synesthesia.
Asunto(s)
Percepción de Color/fisiología , Reconocimiento Visual de Modelos/fisiología , Sinestesia/fisiopatología , Adolescente , Adulto , Anciano , Femenino , Humanos , Magnetoencefalografía , Masculino , Persona de Mediana Edad , Estimulación Luminosa , Tiempo de Reacción/fisiología , Sinestesia/diagnóstico por imagen , Adulto JovenRESUMEN
Being able to empathise with others is a crucial ability in everyday life. However, this does not usually entail feeling the pain of others in our own bodies. For individuals with mirror-sensory synaesthesia (MSS), however, this form of empathic embodiment is a common feature. Our study investigates the empathic ability of adults who experience MSS using a video-based empathy task. We found that MSS participants did not differ from controls on emotion identification and affective empathy; however, they showed higher affect sharing (degree to which their affect matches what they attribute to others) than controls. This finding indicates difficulties with self-other distinction, which our data shows results in fewer signs of prosocial behaviour. Our findings are in line with the self-other control theory of MSS and highlight how the use of appropriate empathy measures can contribute to our understanding of this important socio-affective ability, both in typical and atypical populations.
Asunto(s)
Emociones , Empatía , Sinestesia , Humanos , Empatía/fisiología , Masculino , Femenino , Adulto , Emociones/fisiología , Adulto Joven , Trastornos de la Percepción/fisiopatologíaRESUMEN
INTRODUCTION: We report on a musician who acquired synesthesia, enhanced sensory experience, and improved creativity following traumatic brain injury (TBI). BACKGROUND: Creativity and synesthesia can be acquired from an injury, though both simultaneously has not been frequently documented. NARRATIVE: This case report details heightened creativity and developing synesthesia in a 66-year-old right-handed man following TBI. He developed a "compulsion" to write music. Synesthesia included "seeing" the notation and being able to name chord structures of music he heard, both of which were novel experiences. The Synesthesia Battery revealed a vision-sound synesthesia with higher than average level of Vividness of Visual Imagery (VVIQ-2), and "Absolute Pitch/Perfect Pitch." PATIENT EXPERIENCE: The patient experienced an approximate four-month history of these changes, including musical compositions, developing perfect pitch, and enhanced sensory experience of typical phenomena. DISCUSSION: Both creativity and synesthesia depend on novel connections in the brain, and both have been reported following insults to the brain, including in degenerative conditions. However, the development of both simultaneously is not frequently reported. Evidence for the etiology of one prompting the other has not been described. Brain injury may result in increased creativity and synesthesia. Our fields would benefit from increased awareness of this possible relationship.
Asunto(s)
Lesiones Traumáticas del Encéfalo , Música , Trastornos de la Percepción , Masculino , Humanos , Anciano , Sinestesia , Trastornos de la Percepción/etiología , Encéfalo , Lesiones Traumáticas del Encéfalo/complicaciones , CreatividadRESUMEN
A narrative review of autonomous sensory meridian response (ASMR) was carried out. Definitional factors relevant to ASMR were canvassed. Related, but distinctly unique, sensorial phenomena, including frisson, synaesthesia, and misophonia were considered. Finally, the status of literature with respect to clinical outcomes, individual differences, and current research applications was evaluated. ASMR is a nascent phenomenon that has rapidly progressed in scope and depth of study throughout the past decade; a notable shift from brief-form studies to an increase in formalised trials is noted. Yet, critical questions remain unaddressed, including expectancy and placebo effects, that future research should interrogate.
Asunto(s)
Meridianos , Humanos , Trastornos de la Audición , SinestesiaRESUMEN
The aim of this paper was to assess the genuineness of a case of phoneme color synesthesia (VA) by evaluating the influence of several psycholinguistic levels with different stimuli (isolated vowels, nonsense syllables, and words). Results demonstrate the robustness of the synesthesia no matter what the type of stimuli. To explore how this form of synesthesia manifested itself in everyday conversation, interviews were also conducted. VA reported that, in the context of conversation, phonemes still evoked colors that she had to translate in order to access the meaning. She also reported that her mental representations were multisensorial and that the verbal dimension was almost non-existent. We address several implications of this phoneme color synesthesia: the atypical speech perception that it implies, the cognitive cost of this stable system, and its relation to a specific cognitive functioning.
Asunto(s)
Trastornos de la Percepción , Percepción del Habla , Femenino , Humanos , Sinestesia , Psicolingüística , Cognición , Percepción de Color/fisiología , ColorRESUMEN
Synesthesia is a neurologic trait in which specific inducers, such as sounds, automatically elicit additional idiosyncratic percepts, such as color (thus "colored hearing"). One explanation for this trait-and the one tested here-is that synesthesia results from unusually weak pruning of cortical synaptic hyperconnectivity during early perceptual development. We tested the prediction from this hypothesis that synesthetes would be superior at making discriminations from nonnative categories that are normally weakened by experience-dependent pruning during a critical period early in development-namely, discrimination among nonnative phonemes (Hindi retroflex /d̪a/ and dental /Éa/), among chimpanzee faces, and among inverted human faces. Like the superiority of 6-mo-old infants over older infants, the synesthetic groups were significantly better than control groups at making all the nonnative discriminations across five samples and three testing sites. The consistent superiority of the synesthetic groups in making discriminations that are normally eliminated during infancy suggests that residual cortical connectivity in synesthesia supports changes in perception that extend beyond the specific synesthetic percepts, consistent with the incomplete pruning hypothesis.
Asunto(s)
Cognición/fisiología , Neuroimagen , Reconocimiento Visual de Modelos/fisiología , Sinestesia/diagnóstico por imagen , Adulto , Cara/diagnóstico por imagen , Cara/fisiología , Femenino , Humanos , Masculino , Estimulación Luminosa , Sinestesia/fisiopatologíaRESUMEN
Synesthesia is a phenomenon where sensory stimuli or cognitive concepts elicit additional perceptual experiences. For instance, in a commonly studied type of synesthesia, stimuli such as words written in black font elicit experiences of other colors, e.g., red. In order to objectively verify synesthesia, participants are asked to choose colors for repeatedly presented stimuli and the consistency of their choices is evaluated (consistency test). Previously, there has been no publicly available and easy-to-use tool for analyzing consistency test results. Here, the R package synr is introduced, which provides an efficient interface for exploring consistency test data and applying common procedures for analyzing them. Importantly, synr also implements a novel method enabling identification of participants whose scores cannot be interpreted, e.g., who only give black or red color responses. To this end, density-based spatial clustering of applications with noise (DBSCAN) is applied in conjunction with a measure of spread in 3D space. An application of synr with pre-existing openly accessible data illustrating how synr is used in practice is presented. Also included is a comparison of synr's data validation procedure and human ratings, which found that synr had high correspondence with human ratings and outperformed human raters in situations where human raters were easily mislead. Challenges for widespread adoption of synr as well as suggestions for using synr within the field of synesthesia and other areas of psychological research are discussed.
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Trastornos de la Percepción , Humanos , Sinestesia , Percepción de Color/fisiologíaRESUMEN
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.
Asunto(s)
Meridianos , Percepción del Tacto , Humanos , Incidencia , Sinestesia , Tacto , Percepción del Tacto/fisiologíaRESUMEN
OBJECTIVE: Preliminary research suggests that experiences resembling synaesthesia are frequently reported under the influence of a diverse range of chemical substances although the incidence, chemical specificity, and characteristics of these effects are poorly understood. METHODS: Here we surveyed recreational drug users and self-reported developmental synaesthetes regarding their use of 28 psychoactive drugs from 12 different drug classes and whether they had experienced synaesthesia under the influence of these substances. RESULTS: The drug class of tryptamines exhibited the highest incidence rates of drug-induced synaesthesia in controls and induction rates of novel forms of synaesthesia in developmental synaesthetes. Induction incidence rates in controls were strongly correlated with the corresponding induction and enhancement rates in developmental synaesthetes. In addition, the use of lysergic acid diethylamide (LSD) was the strongest predictor of drug-induced synaesthesia in both controls and developmental synaesthetes. Clear evidence was observed for a clustering of synaesthesia-induction rates as a function of drug class in both groups, denoting non-random incidence rates within drug classes. Sound-colour synaesthesia was the most commonly observed type of induced synaesthesia. Further analyses suggest the presence of synaesthesia-prone individuals, who were more likely to experience drug-induced synaesthesia with multiple drugs. CONCLUSIONS: These data corroborate the hypothesized link between drug-induced synaesthesia and serotoninergic activity, but also suggest the possibility of alternative neurochemical pathways involved in the induction of synaesthesia. They further imply that the induction and modulation of synaesthesia in controls and developmental synaesthetes share overlapping mechanisms and that certain individuals may be more susceptible to experiencing induced synaesthesia with different drugs.
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Percepción de Color , Dietilamida del Ácido Lisérgico , Humanos , Autoinforme , Encuestas y Cuestionarios , SinestesiaRESUMEN
It is unclear whether synesthesia is one condition or many, and this has implications for whether theories should postulate a single cause or multiple independent causes. Study 1 analyses data from a large sample of self-referred synesthetes (N = 2,925), who answered a questionnaire about N = 164 potential types of synesthesia. Clustering and factor analysis methods identified around seven coherent groupings of synesthesia, as well as showing that some common types of synesthesia do not fall into any grouping at all (mirror-touch, hearing-motion, tickertape). There was a residual positive correlation between clusters (they tend to associate rather than compete). Moreover, we observed a "snowball effect" whereby the chances of having a given cluster of synesthesia go up in proportion to the number of other clusters a person has (again suggesting non-independence). Clusters tended to be distinguished by shared concurrent experiences rather than shared triggering stimuli (inducers). We speculate that modulatory feedback pathways from the concurrent to inducers may play a key role in the emergence of synesthesia. Study 2 assessed the external validity of these clusters by showing that they predict performance on other measures known to be linked to synesthesia.
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Trastornos de la Percepción , Percepción del Tacto , Percepción de Color , Humanos , SinestesiaRESUMEN
INTRODUCTION: This study determines whether there is a familial aggregation between synaesthesia and two neuropsychiatric conditions (autism and schizophrenia). METHOD We examined the prevalence of autism and schizophrenia among synaesthetes and non-synaesthetic controls, and among their first-degree relatives. RESULTS: As predicted, autism occurred at elevated levels among synaesthetes and-we document for the first time-amongst their relatives. This was not found for schizophrenia, where a link may be expected, or in a control condition (type 1 diabetes) where we had no a priori reason to assume a link. Synaesthetes, compared to controls, were also more likely to have other synaesthetes in their family. People with three or more types of synaesthesia were more likely (compared to synaesthetes with fewer types) to have synaesthetic relatives and to report autism in themselves. People with two or more types of synaesthesia (compared to synaesthetes with only one type) were more likely to report familial autism. CONCLUSIONS: The results suggest a shared genetic predisposition between synaesthesia and autism, and more extreme synaesthetes may tend to hail from more neurodiverse families.
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Trastorno Autístico , Esquizofrenia , Trastorno Autístico/epidemiología , Trastorno Autístico/genética , Percepción de Color , Humanos , Esquizofrenia/epidemiología , Esquizofrenia/genética , SinestesiaRESUMEN
In 1883, Henri Gourdan de Fromentel defended his thesis on an original topic that has not really been studied since. He examined the simultaneous perception of pain in two distinct and distant, but homolateral, areas of the body following a single stimulation on himself. In the discussion he compared his synalgia with other types of synaesthesia that did not involve pain and concluded that it was likely to be of central nervous system origin. After a brief account of Fromentel's life, this article discusses his thesis and a book on the subject he published five years later in the light of current understanding of the phenomenon and the proximity of synalgia and allachaesthesia.
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Sistema Nervioso Central , Dolor , Humanos , Masculino , Dolor/etiología , SinestesiaRESUMEN
The aim of this article is to reposition synaesthesia as model system for understanding variation in the construction of the human mind and brain. People with synaesthesia inhabit a remarkable mental world in which numbers can be coloured, words can have tastes, and music is a visual spectacle. Key questions remain unanswered about why it exists, and how the study of synaesthesia might inform theories of the human mind. This article argues we need to rethink synaesthesia as not just representing exceptional experiences, but as a product of an unusual neurodevelopmental cascade from genes to brain to cognition of which synaesthesia is only one outcome. Specifically, differences in the brains of synaesthetes support a distinctive way of thinking (enhanced memory, imagery etc.) and may also predispose towards particular clinical vulnerabilities. In effect, synaesthesia can act as a paradigmatic example of a neuropsychological approach to individual differences.
Asunto(s)
Encéfalo , Música , Cognición , Percepción de Color , Cara , Humanos , SinestesiaRESUMEN
Consistency of synesthetic associations over time is a widely used test of synesthesia. Since many studies suggest that consistency is not a completely reliable feature, we compared the consistency and strength of synesthetes' grapheme-color associations. Consistency was measured by scores on the Synesthesia Battery and by the Euclidean distance in color space for the specific graphemes tested for each participant. Strength was measured by congruency magnitudes on the Implicit Association Test. The strength of associations was substantially greater for synesthetes than non-synesthetes, suggesting that this is a novel, objective marker of synesthesia. Although, intuitively, strong associations should also be consistent, consistency and strength were uncorrelated, indicating that they are likely independent, at least for grapheme-color synesthesia. These findings have implications for our understanding of synesthesia and for estimates of its prevalence since synesthetes who experience strong, but inconsistent, associations may not be identified by tests that focus solely on consistency.