Grapheme-Color Synesthesia and Its Connection to Memory.

Synesthesia is the involuntary association of different senses, where individuals experience one sensory modality in response to the stimulation of another. For example, a synesthete may perceive colors when reading certain numbers or associate specific tastes with particular words. Synesthesia manifests differently for individuals grouping the condition in subcategories such as grapheme-color, sound-to-color, lexical-gustatory, mirror-touch, and much more. This review covers grapheme-color synesthesia, described as the involuntary perception of specific colors or color associations when seeing or thinking about certain letters, numbers, or symbols. This review explores the performance of declarative memory tasks in individuals with grapheme-color synesthesia. A comprehensive search of controlled trials published between 2014 to 2024 was conducted through PubMed and Google Scholar databases. In Google Scholar, the search terms grapheme-color synesthesia, grapheme-color synaesthesia, and memory were used. In PubMed, additional MeSH (Medical Subject Headings) terms were used which included grapheme-color synesthesia and memory. Studies that measured declarative memory and grapheme-color synesthesia were included yielding a total of seven controlled trials. Grapheme-color synesthetes demonstrated advanced performance in declarative memory tasks; however, this may not have any clinical significance. Grapheme-color synesthetes demonstrated a better performance in their ability to recall colors, but not as much recalling words. Synesthetes were shown to outperform non-synesthetes in visual memory tasks. Synesthetes showed better recall of paired patterns, shape-color associations, and visual grids compared to control groups, but the influence of synesthesia on word memory remains unclear. Future research should consider adding control for confounding factors, collaborating with other institutions, and increasing sample size.

Investigation of the relationship between neuroplasticity and grapheme-color synesthesia.

Grapheme-color synesthesia is a normal and healthy variation of human perception. It is characterized by the association of letters or numbers with color perceptions. The etiology of synesthesia is not yet fully understood. Theories include hyperconnectivity in the brain, cross-activation of adjacent or functionally proximate sensory areas of the brain, or various models of lack of inhibitory function in the brain. The growth factor brain-derived neurotrophic (BDNF) plays an important role in the development of neurons, neuronal pathways, and synapses, as well as in the protection of existing neurons in both the central and peripheral nervous systems. ELISA methods were used to compare BDNF serum concentrations between healthy test subjects with and without grapheme-color synesthesia to establish a connection between concentration and the occurrence of synesthesia. The results showed that grapheme-color synesthetes had an increased BDNF serum level compared to the matched control group. Increased levels of BDNF can enhance the brain's ability to adapt to changing environmental conditions, injuries, or experiences, resulting in positive effects. It is discussed whether the integration of sensory information is associated with or results from increased neuroplasticity. The parallels between neurodegeneration and brain regeneration lead to the conclusion that synesthesia, in the sense of an advanced state of consciousness, is in some cases a more differentiated development of the brain rather than a relic of early childhood.

Exploring the correlates and nature of subjective anomalous interactions with objects (psychometry): a mixed methods survey.

Introduction: Psychometry refers to the experience of receiving information about a person or thing by contact with a given object. There is little research to date on the psychological correlates of psychometry and no systematic qualitative research on the nature of the experience itself. Method: A convergent mixed methods online survey sought to explore how synesthesia and autonomous sensory meridian response (ASMR) correlate with a range of anomalous experiences, including psychometry, among members of the public. Those who reported that they had experienced psychometry were invited to describe their experiences in an open ended section. Results: Results indicate that those who experience psychometry scored higher on a measure of ASMR than those who did not. Those who experience synesthesia also scored significantly higher on a measure of ASMR than those who did not. However, synesthesia was not significantly associated with psychometry. Both ASMR and synesthesia were associated with tendencies to report anomalous experiences (with and without a paranormal attribution). A thematic analysis found five themes including: a flash of imagery; lived feelings and intense emotions; noesis and perspective taking/empathy. Subjective psychometry experiences seem to reflect emotional information that is experienced as different to one's normal experiences and felt to be from the perspective of another person. Discussion: Results are discussed and quantitative and qualitative findings are integrated.

Neural mechanisms of costly helping in the general population and mirror-pain synesthetes.

It has been argued that experiencing the pain of others motivates helping. Here, we investigate the contribution of somatic feelings while witnessing the pain of others onto costly helping decisions, by contrasting the choices and brain activity of participants that report feeling somatic feelings (self-reported mirror-pain synesthetes) against those that do not. Participants in fMRI witnessed a confederate receiving pain stimulations whose intensity they could reduce by donating money. The pain intensity could be inferred either from the facial expressions of the confederate in pain (Face condition) or from the kinematics of the pain-receiving hand (Hand condition). Our results show that self-reported mirror-pain synesthetes increase their donation more steeply, as the intensity of the observed pain increases, and their somatosensory brain activity (SII and the adjacent IPL) was more tightly associated with donation in the Hand condition. For all participants, activation in insula, SII, TPJ, pSTS, amygdala and MCC correlated with the trial by trial donation made in the Face condition, while SI and MTG activation was correlated with the donation in the Hand condition. These results further inform us about the role of somatic feelings while witnessing the pain of others in situations of costly helping.

Wearable sensors to measure the influence of sonic seasoning on wine consumers in a live context: a preliminary proof-of-concept study.

BACKGROUND: Any action capable of creating expectations about product quality would be able to modulate experienced pleasantness. In this context, during the 2022 edition of the Internet Festival (Pisa, Italy) a 'social experiment' was promoted to set up an affordable and reliable methodology based on wearable sensors to measure the emotions aroused in a live context on consumers by different kinds of wines. Therefore, five wines (two faulty ones and three high-quality samples) were proposed to 50 non-selected consumers in an arousing context with live jazz music as background. Both explicit (questionnaires) and two different approaches for implicit methods (electrocardiogram (ECG) recorded by wearable sensors vs. smartphones), the latter performed on a subgroup of 16, to measure the emotions aroused by wines and music were utilized synergistically. RESULTS: According to our findings: (i) wine undoubtedly generates a significant emotional response on consumers; (ii) this answer is multifaceted and attributable to the quality level of the wine tasted. In fact, all things being equal, while drinking wine even untrained consumers can perfectly recognize good wines compared to products of lower quality; (iii) high-quality wines are able to induce a spectrum of positive emotions, as observed by the analysis of ECG signals, especially when they are coupled with background music. CONCLUSION: The framework has certainly played to the advantage of good-quality wines, fostering their positive emotional characteristics on the palate even of some less experienced consumers, thanks to a dragging effect towards a positive mood generated by the surrounding conditions (good music in a beautiful location). © 2024 Society of Chemical Industry.

Induced awareness of synesthetic sensations in synesthetically predisposed "Borderline Non-synesthetes".

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.

Is non-synesthetes' B Blue? Grapheme-color association improves non-synesthetes' detection in visual search.

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.

The advantage of being a synesthete: The behavioral benefits of ticker-tape synesthesia.

As first described by Francis Galton, some persons perceive vividly and automatically in their mind's eye the written form of words that they are hearing. This phenomenon, labeled ticker-tape synesthesia (TTS), is thought to reflect an abnormally strong influence of speech processing in language areas on to orthographic representations in the visual cortex. Considering the relevance of TTS for the study of reading acquisition, we looked for objective behavioral advantages or impairments in 22 synesthetes, as compared to 22 matched control participants. In three auditory tasks relying on orthographic working memory (letters counting, backward spelling, and letter shape decision), we predicted and observed better performance in synesthetes than in controls. In two visual tasks (lexical decision and letter decision) with a concurrent auditory stimulation, we predicted that synesthetes should suffer from a larger interference by irrelevant speech than controls, but eventually found no difference between the groups. Those results, which we discuss in relation to orthographic processing, mental imagery, and working memory, promote TTS from pure subjectivity to an experimentally measurable phenomenon.

The cloud of unknowing: Cognitive dedifferentiation in whole-body perceptual deprivation.

An altered sensory environment, especially a homogeneous one like a ganzfeld, can induce a wide range of experiences in people immersed in it. The ganzfeld of our current focus is the OVO Whole-Body Perceptual Deprivation chamber (OVO-WBPD). Previous literature has found this specific immersive environment to be capable of softening and dissolving perception of boundaries across time and sensory modalities, among other domains. Since recent published electrophysiological results demonstrated that immersion in the OVO-WBPD significantly increased delta and beta activity, in the left inferior frontal cortex and in the left insula, we sought to better understand the subjective experiences of participants utilizing this altered sensory environment via semi-qualitative methodology. Consequently, semi-structured interviews of participants were analyzed by three independent evaluators focusing on several domains of experience often reported in perceptual deprivation environments. We found a significantly shared consensus on the presence of experiences belonging to semantic domains of altered experience, demonstrating that the OVO-WBPD chamber consistently elicits positively connotated, bodily-oriented and cognitively dedifferentiated subjective states of consciousness in the majority of 32 examined participants.

A case report of acquired synesthesia and heightened creativity in a musician after traumatic brain injury.

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.