Do the colors of your letters depend on your language? Language-dependent and universal influences on grapheme-color synesthesia in seven languages.

Grapheme-color synesthetes experience graphemes as having a consistent color (e.g., "N is turquoise"). Synesthetes' specific associations (which letter is which color) are often influenced by linguistic properties such as phonetic similarity, color terms ("Y is yellow"), and semantic associations ("D is for dog and dogs are brown"). However, most studies of synesthesia use only English-speaking synesthetes. Here, we measure the effect of color terms, semantic associations, and non-linguistic shape-color associations on synesthetic associations in Dutch, English, Greek, Japanese, Korean, Russian, and Spanish. The effect size of linguistic influences (color terms, semantic associations) differed significantly between languages. In contrast, the effect size of non-linguistic influences (shape-color associations), which we predicted to be universal, indeed did not differ between languages. We conclude that language matters (outcomes are influenced by the synesthete's language) and that synesthesia offers an exceptional opportunity to study influences on letter representations in different languages.

Electropneumotactile Stimulation: Multimodal Haptic Actuators Enabled by a Stretchable Conductive Polymer on Inflatable Pockets.

This paper describes a type of haptic device that delivers two modes of stimulation simultaneously and at the same locations on the skin. The two modes of stimulation are mechanical (delivered pneumatically by inflatable air pockets embedded within a silicone elastomer) and electrical (delivered by a conductive polymer). The key enabling aspect of this work is the use of a highly plasticized conductive polymer based on poly(3,4-ethylenedioxythiphene) (PEDOT) blended with elastomeric polyurethane (PU). To fabricate the "electropneumotactile" device, the polymeric electrodes are overlaid directly on top of the elastomeric pneumatic actuator pockets. Co-placement of the pneumatic actuators and the electrotactile electrodes is enabled by the stretchability of the PEDOT:OTs/PU blend, allowing the electrotactiles to conform to underlying pneumatic pockets under deformation. The blend of PEDOT and PU has a Young's modulus of ~150 MPa with little degradation in conductivity following repeated inflation of the air pockets. The ability to perceive simultaneous delivery of two sensations to the same location on the skin are supported by experiments using human subjects. These results show that participants can successfully detect the location of pneumatic stimulation and whether electrotactile stimulation is delivered (yes/no) at a rate significantly above chance (mean accuracy = 94%).

Virtual Texture Generated using Elastomeric Conductive Block Copolymer in Wireless Multimodal Haptic Glove.

Haptic devices are in general more adept at mimicking the bulk properties of materials than they are at mimicking the surface properties. This paper describes a haptic glove capable of producing sensations reminiscent of three types of near-surface properties: hardness, temperature, and roughness. To accomplish this mixed mode of stimulation, three types of haptic actuators were combined: vibrotactile motors, thermoelectric devices, and electrotactile electrodes made from a stretchable conductive polymer synthesized in our laboratory. This polymer consisted of a stretchable polyanion which served as a scaffold for the polymerization of poly(3,4-ethylenedioxythiophene) (PEDOT). The scaffold was synthesized using controlled radical polymerization to afford material of low dispersity, relatively high conductivity (0.1 S cm-1), and low impedance relative to metals. The glove was equipped with flex sensors to make it possible to control a robotic hand and a hand in virtual reality (VR). In psychophysical experiments, human participants were able to discern combinations of electrotactile, vibrotactile, and thermal stimulation in VR. Participants trained to associate these sensations with roughness, hardness, and temperature had an overall accuracy of 98%, while untrained participants had an accuracy of 85%. Sensations could similarly be conveyed using a robotic hand equipped with sensors for pressure and temperature.

Organic Haptics: Intersection of Materials Chemistry and Tactile Perception.

The goal of the field of haptics is to create technologies that manipulate the sense of touch. In virtual and augmented reality, haptic devices are for touch what loudspeakers and RGB displays are for hearing and vision. Haptic systems that utilize micromotors or other miniaturized mechanical devices (e.g., for vibration and pneumatic actuation) produce interesting effects, but are quite far from reproducing the feeling of real materials. They are especially deficient in recapitulating surface properties: fine texture, friction, viscoelasticity, tack, and softness. The central argument of this Progress Report is that to reproduce the feel of everyday objects requires chemistry: molecular control over the properties of materials and ultimately design of materials which can change these properties in real time. Stimuli-responsive organic materials, such as polymers and composites, are a class of materials which can change their oxidation state, conductivity, shape, and rheological properties, and thus might be useful in future haptic technologies. Moreover, the use of such materials in research on tactile perception could help elucidate the limits of human tactile sensitivity. The work described represents the beginnings of this new area of inquiry, in which the defining approach is the marriage of materials science and psychology.

Grapheme-Color Synesthesia in an Abugida: a Bengali Case Study.

Grapheme-color synesthetes experience graphemes (e.g., letters of the alphabet) as having a specific, consistent color. Most studies of grapheme-color synesthesia have only examined synesthetes in English, leaving underexplored the question of how synesthetic phenomenology might differ in languages that do not use alphabets. In particular, grapheme-color synesthesia in an abugida (a segmental writing system in which vowels are added to consonant graphemes using 'accent'-like diacritical marks) has never been studied. Here, we present a case study of a Bengali synesthete, MJ, the first report of a grapheme-color synesthete in an abugida. First, we show that for MJ, diacritics influence the overall color of the consonant grapheme they modify, 'pulling' it toward the color she experiences for the vowel. Second, we describe and analyze the complex synesthetic experiences reported by MJ for conjunct graphemes, a unique orthographic feature of Brahmi-derived scripts (such as Bengali) in which multiple graphemes are visually combined into a single 'merged' grapheme. Finally, we show that in addition to these language-specific features, MJ's synesthetic associations are influenced by some of the same linguistic properties (such as orthography and phonology) that influence synesthetic associations in other languages. We conclude that the idiosyncratic features of MJ's synesthesia reflect unique properties of the Bengali writing system, that more studies of synesthesia in non-alphabetic scripts are needed, and that synesthetic phenomenology can offer insights into how linguistic properties shape grapheme representation in the brain.

Echoes from the past: synaesthetic colour associations reflect childhood gender stereotypes.

Grapheme-colour synaesthesia is a neurological phenomenon in which linguistic symbols evoke consistent colour sensations. Synaesthesia is believed to be influenced by both genetic and environmental factors, but how these factors interact to create specific associations in specific individuals is poorly understood. In this paper, we show that a grapheme-colour association in adult synaesthetes can be traced to a particular environmental effect at a particular moment in childhood. We propose a model in which specific grapheme-colour associations are 'locked in' during development in children predisposed to become synaesthetes, whereas grapheme-colour associations remain flexible in non-synaesthetes. We exploit Western gender-colour stereotypes to test our model: we found that young girls in general tend to associate their first initial with the colour pink. Consistent with our model, adult female synaesthetes are influenced by their childhood environment: they associate their first initial with pink. Adult female non-synaesthetes do not show this bias. Instead, in our study, non-synaesthetes tended to associate their first initial with their current favourite colour. The results thus support the 'locking in' model of synaesthesia, suggesting that synaesthetic associations can be used as a 'time capsule', revealing childhood influences on adult linguistic associations. Grapheme-colour synaesthesia may thus offer an extraordinary opportunity to study linguistic development. This article is part of a discussion meeting issue 'Bridging senses: novel insights from synaesthesia'.

Mirror feedback assisted recovery from hemiparesis following stroke. In Reply to Morkisch et al.: How to perform mirror therapy after stroke? Evidence from a meta-analysis.

1 out of 6 people worldwide will have suffered a stroke in their lifetime, 1/3rd of whom will die. Of the 2/3rd who survive, half will be permanently disabled (World Stroke Organization). Given these alarming statistics, it's not surprising that tremendous of amounts of time, resources and funding have been devoted towards research into stroke rehab. In view of this, simple, easy-to-implement procedures are highly sought after. One such procedure is the use of visual feedback conveyed by a mirror, which seems to reactivate some dormant pathways in patients who have suffered a recent stroke (Altschuler et al., 1999; Ramachandran & Altschuler, 2009). This procedure has been validated in several dozen clinical trials, of which a substantial number were conducted rigorously. Morkisch et al. (2019) now present a systematic review and meta-analysis of this dense literature pertaining to this topic. They conclude that "there is a high level evidence for mirror therapy's effectiveness in treating post-stroke hemiparesis". A novel conclusion that emerged from this meta-analysis was that the larger the mirror the more effective the treatment is. Additionally, if an object is manipulated by the normal hand and its reflection viewed in the mirror, the procedure is not as effective, possibly because the discrepancy of signals between the visual feedback (reflection of the object) and the lack of confirmatory somatosensory input from the affected limb leads to inhibition rather than synergy. Lastly, for reasons yet unclear, sending movement commands to the unaffected hand alone (unilateral) is more effective than sending bilateral commands, contrary to the original protocol.Taken collectively, research in this field has two implications - First, the immediate practical utility in the clinic by optimizing mirror therapy's efficacy for hemiparesis after stroke. Second, it leads to a rejection of the model of the brain as made up of isolated, autonomous modules, towards a more dynamic picture, in which the brain is composed of a fluctuating mosaic of neural activity as it adapts to changing sensory inputs. Therefore, dysfunction results not from 'punch out a module - lose a function', but by shifts in equilibria, which can be corrected, perhaps, by hitting a reset button. Even if this turns out to be true for a minority of syndromes, it will be well worth the effort.

Role of indentation depth and contact area on human perception of softness for haptic interfaces.

In engineering, the "softness" of an object, as measured by an indenter, manifests as two measurable parameters: (i) indentation depth and (ii) contact area. For humans, softness is not well defined, although it is believed that perception depends on the same two parameters. Decoupling their relative contributions, however, has not been straightforward because most bulk-"off-the-shelf"-materials exhibit the same ratio between the indentation depth and contact area. Here, we decoupled indentation depth and contact area by fabricating elastomeric slabs with precise thicknesses and microstructured surfaces. Human subject experiments using two-alternative forced-choice and magnitude estimation tests showed that the indentation depth and contact area contributed independently to perceived softness. We found an explicit relationship between the perceived softness of an object and its geometric properties. Using this approach, it is possible to design objects for human interaction with a desired level of perceived softness.

"Fake it till You Make it"! Contaminating Rubber Hands ("Multisensory Stimulation Therapy") to Treat Obsessive-Compulsive Disorder.

Obsessive-compulsive disorder (OCD) is a deeply enigmatic psychiatric condition associated with immense suffering worldwide. Efficacious therapies for OCD, like exposure and response prevention (ERP), are sometimes poorly tolerated by patients. As many as 25% of patients refuse to initiate ERP mainly because they are too anxious to follow exposure procedures. Accordingly, we proposed a simple and tolerable (immersive yet indirect) low-cost technique for treating OCD that we call "multisensory stimulation therapy." This method involves contaminating a rubber hand during the so-called "rubber hand illusion" (RHI) in which tactile sensations may be perceived as arising from a fake hand. Notably, Jalal et al. (2015) showed that such fake hand contamination during the RHI provokes powerful disgust reactions in healthy volunteers. In the current study, we explored the therapeutic potential of this novel approach. OCD patients (n = 29) watched as their hidden real hand was being stroked together with a visible fake hand; either synchronously (inducing the RHI; i.e., the experimental condition; n = 16) or asynchronously (i.e., the control condition; n = 13). After 5 min of tactile stimulation, the rubber hand was contaminated with fake feces, simulating conventional exposure therapy. Intriguingly, results suggested sensory assimilation of contamination sensations into the body image via the RHI: patients undergoing synchronous stimulation did not report greater contamination sensations when the fake hand was initially contaminated relative to asynchronous stroking. But contrary to expectations, they did so after the rubber hand had been contaminated for 5 min, as assessed via disgust facial expressions (a secondary outcome) and in vivo exposure (upon discontinuing the illusion). Further, to our surprise, synchronous and asynchronous stroking induced an equally vivid and fast-emerging illusion, which helps explain why both conditions initially (5 min after initiating tactile stimulation) provoked contamination reactions of equal magnitude. This study is the first to suggest heightened malleability of body image in OCD. Importantly, it may pave the way for a tolerable technique for the treatment of OCD-highly suitable for poorly resourced and emergency settings, including low-income and developing countries with minimal access to high-tech solutions like virtual reality.

Novel Smartphone Interventions Improve Cognitive Flexibility and Obsessive-Compulsive Disorder Symptoms in Individuals with Contamination Fears.

One type of obsessive-compulsive disorder (OCD) is characterized by contamination fears and compulsive cleansing. Few effective treatments are available for this debilitating condition. Compulsive symptoms, such as excessive washing, are believed to be mediated by cognitive inflexibility-arguably the most striking cognitive impairment in OCD. In this study, we investigated the effects of two novel smartphone interventions on cognitive flexibility and OCD symptoms in healthy individuals with OCD-like contamination fears. In the first intervention, participants watched a brief video recording of themselves engaging in handwashing on a smartphone, four times a day, for a total of one week (N = 31). The second intervention was similar except that participants watched themselves repeatedly touching a disgust-inducing object (N = 31). In a third (control) "intervention", participants watched themselves performing sequential hand movements (N = 31). As hypothesized, the two smartphone interventions, unlike the control, improved cognitive flexibility; as assessed on the Intradimensional-Extradimensional Set Shifting task (a sensitive marker of cognitive flexibility). The two interventions, unlike the control, also improved OCD symptoms (measured with the Obsessive-Compulsive Inventory-Revised and Yale-Brown Obsessive-Compulsive Scale). Finally, we found high levels of adherence to the interventions. These findings have significant clinical implications for OCD.

Relief from intractable phantom pain by combining psilocybin and mirror visual-feedback (MVF).

AL's leg was amputated resulting in phantom-limb pain (PLP). (1) When a volunteer placed her foot on or near the phantom - touching it evoked organized sensations in corresponding locations on AL's phantom. (2) Mirror-visual-feedback (MVF) relieved PLP, as did, "phantom massage". (3) Psilocybin-MVF pairing produced synergistic effects, complete elimination of PLP, and reduction in paroxysmal episodes. (4) Touching the volunteer's leg where AL previously had external fixators, evoked sensation of nails boring through the leg. Using a "telescoping" nail, we created the illusion of a nail being removed with corresponding pain relief. (5) Artificial flames produced warmth in the phantom.

Interpersonal gargalesthesia.

When someone touches, say, your upper arm, mirror neurons in your brain's area S2 fire. These neurons also fire when you merely watch another person being touched. However, you do not literally feel the touch from his arm on your own skin. Consistent with this view, we find when someone's arm is removed, he does start experiencing another's sensations [Ramachandran, V. S., & Brang, D. (2009)]. A congenital variant of this syndrome also exists, as in our subject TC. TC experienced referred touch, referred tickle in her axilla, and was able to tickle herself.

Why is the synesthete's "A" red? Using a five-language dataset to disentangle the effects of shape, sound, semantics, and ordinality on inducer-concurrent relationships in grapheme-color synesthesia.

Grapheme-color synesthesia is a neurological phenomenon in which viewing a grapheme elicits an additional, automatic, and consistent sensation of color. Color-to-letter associations in synesthesia are interesting in their own right, but also offer an opportunity to examine relationships between visual, acoustic, and semantic aspects of language. Research using large populations of synesthetes has indeed found that grapheme-color pairings can be influenced by numerous properties of graphemes, but the contributions made by each of these explanatory factors are often confounded in a monolingual dataset (i.e., only English-speaking synesthetes). Here, we report the first demonstration of how a multilingual dataset can reveal potentially-universal influences on synesthetic associations, and disentangle previously-confounded hypotheses about the relationship between properties of synesthetic color and properties of the grapheme that induces it. Numerous studies have reported that for English-speaking synesthetes, "A" tends to be colored red more often than predicted by chance, and several explanatory factors have been proposed that could explain this association. Using a five-language dataset (native English, Dutch, Spanish, Japanese, and Korean speakers), we compare the predictions made by each explanatory factor, and show that only an ordinal explanation makes consistent predictions across all five languages, suggesting that the English "A" is red because the first grapheme of a synesthete's alphabet or syllabary tends to be associated with red. We propose that the relationship between the first grapheme and the color red is an association between an unusually-distinct ordinal position ("first") and an unusually-distinct color (red). We test the predictions made by this theory, and demonstrate that the first grapheme is unusually distinct (has a color that is distant in color space from the other letters' colors). Our results demonstrate the importance of considering cross-linguistic similarities and differences in synesthesia, and suggest that some influences on grapheme-color associations in synesthesia might be universal.

Effect of Grouping, Segmentation, and Vestibular Stimulation on the Autokinetic Effect.

We report some new observations on what could be regarded as the world's simplest visual illusion-the autokinetic effect. When a single dim spot of light is viewed in a completely dark room, it moves vividly in random directions. During steady fixation, perhaps subtle eye movements cause the image to move and a failure to correct for this using eye movement command signals leads to motion perception. This is especially true because eye muscle fatigue can lead to miscalibration. However, if two dots are shown, they often move independently in different directions, which negate the eye movement theory. In addition, two lines defining a single cross sometimes uncouple and slide past each other and the fragments composing a hidden object move independently until they click in place and the whole object is perceived-implying that the illusion occurs relatively late in visual processing. Finally, the effect is modulated by vestibular stimulation; anchoring your sense of self may be a prerequisite for binding features into coherent objects.

Trigger Features for Conveying Facial Expressions: The Role of Segmentation.

Primates are especially good at recognizing facial expression using two contrasting strategies-an individual diagnostic feature (e.g., raise eyebrows or lower mouth corner) versus a relationship between features. We report several novel experiments that demonstrate a profound role of grouping and segmentation-including stereo-on recognition of facial expressions.

The Evolutionary Psychology of Envy and Jealousy.

The old dogma has always been that the most complex aspects of human emotions are driven by culture; Germans and English are thought to be straight-laced whereas Italians and Indians are effusive. Yet in the last two decades there has been a growing realization that even though culture plays a major role in the final expression of human nature, there must be a basic scaffolding specified by genes. While this is recognized to be true for simple emotions like anger, fear, and joy, the relevance of evolutionary arguments for more complex nuances of emotion have been inadequately explored. In this paper, we consider envy or jealousy as an example; the feeling evoked when someone is better off than you. Our approach is broadly consistent with traditional evolutionary psychology (EP) approaches, but takes it further by exploring the complexity and functional logic of the emotion - and the precise social triggers that elicit them - by using deliberately farfetched, and contrived "thought experiments" that the subject is asked to participate in. When common sense (e.g., we should be jealous of Bill Gates - not of our slightly richer neighbor) appears to contradict observed behavior (i.e., we are more envious of our neighbor) the paradox can often be resolved by evolutionary considerations which h predict the latter. Many - but not all - EP approaches fail because evolution and common sense do not make contradictory predictions. Finally, we briefly raise the possibility that gaining deeper insight into the evolutionary origins of certain undesirable emotions or behaviors can help shake them off, and may therefore have therapeutic utility. Such an approach would complement current therapies (such as cognitive behavior therapies, psychoanalysis, psychopharmacologies, and hypnotherapy), rather than negate them.

"I feel your disgust and relief": can the action understanding system (mirror neuron system) be recruited to induce disgust and relief from contamination vicariously, in individuals with obsessive-compulsive disorder symptoms?

Research has shown that brain regions mediating disgust (e.g., the insula) become activated when viewing others' disgust, a response mediated, perhaps by the mirror neuron system or the Theory of Mind module. In a novel behavioral experiment, we explore vicarious disgust and relief, in individuals with obsessive-compulsive disorder (OCD) symptoms. Participants (N = 10) provided disgust ratings to self-contamination or watching the contamination of an experimenter; and to the experimenter washing his own hands after the subjects had been contaminated. To our surprise, we found that subjects experienced disgust from merely watching the experimenter contaminating himself. More intriguingly, after subjects had contaminated themselves, they obtained relief from merely watching the experimenter washing his own hands; even while recognizing the logical absurdity of this. The result is counterintuitive since neither the subjects nor anyone else would have predicted this. These preliminary findings - if confirmed in placebo-controlled studies - might pave the way toward novel therapeutic approaches for OCD.

Altered White Matter and Sensory Response to Bodily Sensation in Female-to-Male Transgender Individuals.

While most people take identification with their body for granted, conditions such as phantom limb pain, alien hand syndrome, and xenomelia suggest that the feeling of bodily congruence is constructed and susceptible to alteration. Individuals with xenomelia typically experience one of their limbs as over-present and aversive, leading to a desire to amputate the limb. Similarly, many transgender individuals describe their untreated sexed body parts as incongruent and aversive, and many experience phantom body parts of the sex they identify with (Ramachandran, 2008). This experience may relate to differences in brain representation of the sexed body part, as suggested in xenomelia (McGeoch et al., 2011). We utilized magnetoencephalography imaging to record brain activity during somatosensory stimulation of the breast-a body part that feels incongruent to most presurgical female-to-male (FtM)-identified transgender individuals-and the hand, a body part that feels congruent. We measured the sensory evoked response in right hemisphere somatosensory and body-related brain areas and found significantly reduced activation in the supramarginal gyrus and secondary somatosensory cortex, but increased activation at the temporal pole for chest sensation in the FtM group (N = 8) relative to non-transgender females (N = 8). In addition, we found increased white matter coherence in the supramarginal gyrus and temporal pole and decreased white matter diffusivity in the anterior insula and temporal pole in the FtM group. These findings suggest that dysphoria related to gender-incongruent body parts in FtM individuals may be tied to differences in neural representation of the body and altered white matter connectivity.

Calendars in the brain; their perceptual characteristics and possible neural substrate.

When we visualize a calendar, we have a vague impression of a rectangular grid hovering in front. But 1% of the population "see" vivid, crisp "calendar form" - e.g. an odd V shape as in subject ML. We found that (1) ML could "read off", months of her calendar - or alternate months - backward, unlike controls; (2) her eyes and index finger unconsciously "tracked" her reading; (3) her calendar moved with her gaze and tilted with her head; (4) after looking at a contracting spiral, her calendar expanded. In a second subject EA, the calendar was body centered and the access to episodic memories was partially "blocked" when she "looked away". Our experiments provide, for the first time, clear unambiguous proof for the veracity and true perceptual nature of the phenomenon. We suggest the calendar is constructed in the angular gyrus and its connections with the hippocampus via the inferior longitudinal fasciculus.