Vilayanur Ramachandran

Vilayanur Ramachandran
University of California, San Diego | UCSD · Department of Psychology

About

147
Publications
84,145
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10,840
Citations
Citations since 2017
6 Research Items
3043 Citations
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20172018201920202021202220230100200300400500
20172018201920202021202220230100200300400500

Publications

Publications (147)
Research
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As noted by Erwin Schrödinger, in the world of physics the subjective vantage point does not exist. Indeed, physics requires that the conscious “self ” who experiences the world be banished from reality. This article highlights this schism running right through the heart of reality using a thought experiment. The reader imagines himself as a twin b...
Article
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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, the...
Article
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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 t...
Article
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Synesthetes, who see printed black letters and numbers as being colored, are thought to have enhanced cross-activation between brain modules for color and form. Since the McCollough effect also results from oriented contours (i.e., form) evoking specific colors, we conjectured that synesthetes may experience an enhanced McCollough effect, and find...
Article
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....
Article
We propose a hypothesis concerning the neural basis of the mental ‘calendar’ we all carry around in our brains, based on observations we made on a 25 year old ‘projector synaesthete’, EA, who displays some novel and instructive features. In addition to her grapheme-color synaesthesia, she has a circular ‘calendar line’, laid out vividly in front of...
Article
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Despite its theoretical and clinical interest, there are no experimental studies exploring obsessive-compulsive disorder (OCD)-like disgust sensations through using somatosensory illusions. Such illusions provide important clues to the nature and limits of multisensory integration and how the brain constructs body image; and may potentially inform...
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 influen...
Article
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The question of whether or not psychoanalysis can be considered scientific has been the subject of considerable debate. While Popper classified psychoanalysis as prescientific (e.g., 1963), Grünbaum proposed that psychoanalysis is mostly falsifiable, and therefore is science, although bad science (e.g., Grünbaum, 1977). Flax (1981) critiqued both P...
Article
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While colors are commonplace in everyday metaphors, relatively little is known about implicit color associations to linguistic or semantic concepts in a general population. In this study, we test color associations for ordered linguistic concepts (letters and days). The culture and language specificity of these effects was examined in a large group...
Article
Grapheme-color synesthetes experience colors when they see printed letters of the alphabet. Currently, we tested four "projector" synesthetes, whose colors evoked by graphemes have sensory support or quale and appear to be restricted spatially to the letters like real colors. We use three different kinds of puzzle pictures that contained hidden let...
Article
We have previously suggested that the social symptoms of autism spectrum disorder (ASD) could be caused in part by a dysfunctional mirror neuron system (MNS). Since the recursive activity of a functioning MNS might enable the brain to integrate visual and motor sensations into a coherent body schema, the deficits in self-awareness often seen in ASD...
Book
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The present day is witnessing an explosion of our understanding of how the brain works at all levels, in which complexity is piled on complexity, and mechanisms of astonishing elegance are being continually discovered. This process is most developed in the major areas of the brain, such as the cortex, thalamus, and striatum. The Claustrum instead f...
Article
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The brain's primary motor and primary somatosensory cortices are generally viewed as functionally distinct entities. Here we show by means of magnetoencephalography with a phantom-limb patient, that movement of the phantom hand leads to a change in the response of the primary somatosensory cortex to tactile stimulation. This change correlates with...
Article
EA experienced colors when she saw printed letters of the alphabet and numbers. We used three different kinds of puzzle pictures that contained hidden letters which required 30 seconds or more for normal people to identify. EA recognized them three times faster. She said that the colors were evoked prior to conscious letter recognition; clueing her...
Article
Full-text available
Time-space synesthesia is a variant of sequence-space synesthesia and involves the involuntary association of months of the year with 2D and 3D spatial forms, such as arcs, circles, and ellipses. Previous studies have revealed conflicting results regarding the association between time-space synesthesia and enhanced spatial processing ability. Here,...
Article
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We investigated the physiological mechanism of grapheme-color synesthesia using metacontrast masking. A metacontrast target is rendered invisible by a mask that is delayed by about 60 ms; the target and mask do not overlap in space or time. Little masking occurs, however, if the target and mask are simultaneous. This effect must be cortical, becaus...
Article
The day following the devastating 2010 earthquake in Haiti, the queue for amputations was more than 1,000 patients long. Surgeons therefore had to resort to guillotine-style amputations, which may increase the prevalence of phantom limb pain – the vivid impression that the limb is not only still present but extremely painful. We have previously sho...
Article
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This paper present a new hypothesis as to the function of the claustrum. Our basic premise is that the claustrum functions as a detector and integrator of synchrony in the axonal trains in its afferent inputs. In the first place an unexpected stimulus sets up a processed signal to the sensory cortex that initiates a focus of synchronized gamma osci...
Article
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Crick and Koch suggested in 2005 that the claustrum might be engaged in sensory binding operations related to consciousness. This might involve, they suggested, widespread waves of information traveling within the claustrum that might depend on networks of gap-junction linked neurons, which were especially sensitive to the timing of inputs. But the...
Article
Our senses interact in daily life through multisensory integration, facilitating perceptual processes and behavioral responses. Numerous multisensory regions have been identified in humans and animals, raising the question of whether a single mechanism can support the dynamic range of experiences and behaviors multisensory processing engenders. The...
Chapter
We suggest that there are "aesthetic universals" analogous to Chomskyan deep structure for language and present several "laws" of aesthetics - some old and some new. We argue that for each law three things are needed; what, why, and how. First a clear statement of it; second an analysis of the underlying functional logic in evolutionary terms and t...
Article
Full-text available
Synesthesia is a perceptual experience in which stimuli presented through one modality will spontaneously evoke sensations in an unrelated modality. The condition occurs from increased communication between sensory regions and is involuntary, automatic, and stable over time. While synesthesia can occur in response to drugs, sensory deprivation, or...
Article
We present a simple method using a dark room and a camera flash to induce three novel “out of body” effects. If one is dark adapted, a brief, bright flash may bleach the photoreceptors, allowing whatever is seen during the flash to be “imprinted” on the retinas for several seconds. 1) To induce a feeling of weightlessness, seated subjects looked at...
Article
We consider a number of syndromes incorporating paradoxical phenomena that lie at the boundary between neurology and psychiatry. Amongst the phenomena we examine are Cotard's Syndrome (belief that one is dead/dying), Capgras Syndrome (belief that a personally familiar person has been replaced by an imposter), and Apotemnophilia (desire to have a li...
Article
Full-text available
Damage to the right parietal lobe has long been associated with various disorders of body image. The authors have recently suggested that an unusual behavioural condition in which otherwise rational individuals desire the amputation of a healthy limb might also arise from right parietal dysfunction. Four subjects who desired the amputation of healt...
Article
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We report the unusual case of a woman with right upper limb phocomelia who, post-amputation of her right hand following trauma, sprouted a phantom hand that contained five digits, including a phantom thumb and index finger that had been absent since her birth. These two phantom digits were initially half normal size, however, more than three decade...
Article
We report the first case, to our knowledge, of successful return to work of a patient with alexia without agraphia. This case is also interesting as it is the first report of which we are aware of anosognosia for alexia without agraphia: the patient confabulated when asked to read English text, but immediately stated that he could not read Chinese...
Article
Synesthesia is a condition in which an otherwise normal subject "sees" specific colors associated with specific numbers or letters (graphemes). Is this a sensory effect or simply a memory association? Are they simply being "metaphorical" (just as we say cheese tastes "sharp")? We find that synesthetically induced colors can lead to perceptual group...
Article
Fibromyalgia is a condition characterized by long term body-wide pain and tender points in joints, muscles and soft tissues. Other symptoms include chronic fatigue, morning stiffness, and depression. It is well known that these symptoms are exacerbated under periods of high stress. When pain becomes severe enough, the mind can enter what is known a...
Article
Some otherwise normal individuals experience sensations in one sensory modality when a second modality is stimulated. For example, a synesthete may see any given number as always tinged a certain color (e.g. 5' may be green and 6' may be red). We have previously shown that synesthetically induced colors can influence perceptual grouping, can lead t...
Article
What is the neural basis of conscious awareness? Studies of blindsight patients (due to circumscribed V1 lesions) have suggested that V1 is the locus of visual awareness. However, the existence of extensive visual processing without awareness suggests that V1, while necessary for consciousness may not be sufficient. We explored the amount of proces...
Article
Although synesthesia ("seeing sounds" or seeing letters and numbers tinged with specific colors) has been known for over 100 years, only recently has progress been made towards understanding its underlying mechanisms. We have previously demonstrated that synesthesia is a perceptual phenomenon, and suggest that, in some synesthetes, it may be caused...
Article
Grapheme-color synesthesia is a neurological phenomenon in which letters and numbers (graphemes) consistently evoke particular colors (e.g. A may be experienced as red). The cross-activation theory proposes that synesthesia arises as a result of cross-activation between posterior temporal grapheme areas (PTGA) and color processing area V4, while th...
Article
Subjects with grapheme-color synesthesia report that a given number is always associated with a certain color (e.g., ‘5’ may be green). We have previously shown that synesthetes perform better than controls in various perceptual tasks, presumably due to their induced colors (Ramachandran & Hubbard, 2001). This suggests that synesthesia is a sensory...
Article
Background: It has been proposed that individuals with grapheme-color synesthesia have increased levels of connectivity, particularly between V4 and Visual Word Form Area (Hubbard and Ramachandran, 2005 ). To investigate whether increased connectivity may be a widespread phenomenon, we asked whether color and motion interactions are stronger in syn...
Article
Time-space synesthetes report that they experience the months of the year as having a spatial layout. In Study 1, we characterize the phenomenology of calendar sequences produced by synesthetes and non-synesthetes, and show a conservative estimate of time-space synesthesia at 2.2% of the population. We demonstrate that synesthetes most commonly exp...
Article
Autism is a disorder characterized by social withdrawal, impoverished language and empathy, and a profound inability to adopt another's viewpoint - a failure to construct a "theory of mind" for interpreting another person's thoughts and intentions. We previously showed that these symptoms might be explained, in part, by a paucity of mirror neurons....
Article
We report a new apparent motion illusion that illustrates postdiction (instead of prediction) in human motion perception, which implies that events in the future can influence the perception of events in the present. Two black dots were flashed simultaneously on diagonally opposite corners of an imaginary square (top-left and bottom-right) in Frame...
Article
Full-text available
JS was a grapheme-color synesthete in whom numerals and letters of the alphabet consistently evoked colors. In the first set of experiments we showed that the color - in a consistent and reliable manner - was most pronounced in the left visual field and in central vision. In the second experiment we devised a novel test for eidetic imagery and show...
Article
Full-text available
Following limb amputation patients continue to feel the vivid presence of a phantom limb. A majority of patients also experience pain in the phantom and sometimes (as in our case DS) the pain is severe. Remarkably we find that optically 'resurrecting' the phantom with a mirror and using a lens to make the phantom appear to shrink caused the pain to...
Chapter
This chapter presents an account that, if correct, brings the misidentification syndromes and asomatognosia into line with the rest of the confabulation syndromes by showing how they also fall under the two-factor theory. We build large, detailed representations of the minds of those close to us. These representations are exquisitely sensitive to c...
Article
This article reviews the potential use of visual feedback, focusing on mirror visual feedback, introduced over 15 years ago, for the treatment of many chronic neurological disorders that have long been regarded as intractable such as phantom pain, hemiparesis from stroke and complex regional pain syndrome. Apart from its clinical importance, mirror...
Article
This chapter proposes an approach to the problem of understanding the mind in a somewhat different way from the traditional ways used in cognitive psychology and neuroscience. Instead of tackling the mind problem head-on, it approaches it by investigating phenomena that are robust and repeatable yet do not fit the big picture of cognitive science a...
Article
There is behavioural evidence that caloric vestibular stimulation (CVS) can alleviate central pain. Several such patients have also noted that it reduces tactile allodynia, an especially ill-understood phenomenon in these patients. The first aim is to use magnetoencephalography (MEG) to study neural activity associated with tactile allodynia in cen...
Article
Full-text available
Single-blind, placebo-controlled case report. Center for Brain and Cognition, University of California, San Diego, CA, USA. We present the case of a 64-year-old woman with right-sided central pain following transverse myelitis of her cervical spinal cord in 2002. We investigated whether her pain could be improved beyond a placebo response by cold c...
Article
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We discuss experiments on two individuals in whom specific textures (e.g., denim, wax, sandpaper, silk, etc.) evoked equally distinct emotions (e.g., depression, embarrassment, relief, and contentment, respectively). The test/retest consistency after 8 months was 100%. A video camera recorded subjects' facial expressions and skin conductance respon...
Article
Grapheme-color synaesthesia is a neurological phenomenon in which particular graphemes, such as the numeral 9, automatically induce the simultaneous perception of a particular color, such as the color red. To test whether the concurrent color sensations in grapheme-color synaesthesia are treated as meaningful stimuli, we recorded event-related brai...
Article
Ideomotor apraxia is a cognitive disorder in which the patient loses the ability to accurately perform learned, skilled actions. This is despite normal limb power and coordination. It has long been known that left supramarginal gyrus lesions cause bilateral upper limb apraxia and it was proposed that this area stored a visual-kinaesthetic image of...
Article
Transsexuals are individuals who identify as a member of the gender opposite to that which they are born. Many transsexuals report that they have always had a feeling of a mismatch between their inner gender-based "body image" and that of their body's actual physical form. Often transsexuals undergo gender reassignment surgery to convert their bodi...
Article
In the modern society of the printed word dyslexia can be distressing and disabling. Commonly dyslexia manifests as a difficulty reading often caused by confusion or reversal of certain letters such as 'b' and 'd', and 'p' and 'q' and 'g'. Here we suggest that one method of remediation or amelioration is to print letters in color such as a 'b' in b...
Article
Dejerine-Roussy Syndrome (thalamic pain syndrome) is characterised by the development of chronic, severe pain in the contralateral half of the body after a thalamic stroke. It is often largely refractory to treatment. In this paper we draw together a number of disparate pieces of knowledge to propose a novel therapy for this condition. There is alr...
Article
Apotemnophilia, or body integrity image disorder (BIID), is characterised by a feeling of mismatch between the internal feeling of how one's body should be and the physical reality of how it actually is. Patients with this condition have an often overwhelming desire for an amputation- of a specific limb at a specific level. Such patients are not ps...
Article
Torsional eye movements are triggered by head tilt and a rotating visual field. We examined whether attention to a misoriented form could also induce torsion. Thirty-six observers viewed an adapting field containing a bright vertical line, and then they viewed a display that was composed of two misoriented words (one rotated clockwise, the other co...
Article
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Patients with Wernicke's or expressive aphasia are able to produce fluent speech, however, this speech may be complete gibberish sounds and totally incomprehensible, or even when comprehensible to a degree is often laced with severe errors and abnormalities such as verbal and phonemic paraphasias and neologisms. Furthermore, patient's with Wernicke...
Article
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Wszyscy chc¹ zrozumieae sztukê. Dlaczego nie próbuj¹ zrozumieae œpiewu ptaków? Pablo Picasso 1. Wstêp Gdyby marsjañski etolog przyby³ na Ziemiê i przyjrza³ siê nam, lu-dziom, by³by zaskoczony wieloma aspektami natury ludzkiej, wœród któ-rych sztuka — nasza sk³onnoœae do tworzenia oraz czerpania przyjemnoœci z malarstwa i rzeŸby — nale¿y na pewno do...
Article
Full-text available
Synesthesia is a condition in which stimulation of one sensory modality causes unusual experiences in a second, unstimulated modality. Although long treated as a curiosity, recent research with a combination of phenomenological, behavioral, and neuroimaging methods has begun to identify the cognitive and neural basis of synesthesia. Here, we review...
Article
Experiments on patients with phantom limbs suggest that neural connections in the adult human brain are much more malleable than previously assumed. Three weeks after amputation of an arm, sensations from the ipsilateral face are referred to the phantom; this effect is caused by the sensory input from the face skin 'invading' and activating deaffer...
Article
The Psychology of Art and the Evolution of the Conscious Brain. by Robert L. Solso. MIT Press, Cambridge, MA, 2004. 296 pp. $45, £29.95. ISBN 0-262-19484-8. Drawing on cognitive science, anthropology, and art history, the author explores how human consciousness perceives and creates visual art.
Article
When viewing a single image in the periphery, such as the number 2, accurate identification is fairly easy, but becomes more difficult with increasing eccentricity. However, if one takes that same image and flanks it to the left and right with other images, (e.g., the number 2 flanked by 5′s (525)), accurate identification becomes much more difficu...
Article
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This article supplements our earlier paper on synaesthesia published in JCS (Ramachandran & Hubbard, 2001a). We discuss the phenomenology of synaesthesia in greater detail, raise several new questions that have emerged from recent studies, and suggest some tentative answers to these questions.
Article
Full-text available
We investigated grapheme--colour synaesthesia and found that: (1) The induced colours led to perceptual grouping and pop-out, (2) a grapheme rendered invisible through `crowding' or lateral masking induced synaesthetic colours --- a form of blindsight --- and (3) peripherally presented graphemes did not induce colours even when they were clearly vi...
Article
Full-text available
We studied two otherwise normal, synaesthetic subjects who 'saw' a specific colour every time they saw a specific number or letter. We conducted four experiments in order to show that this was a genuine perceptual experience rather than merely a memory association. (i) The synaesthetically induced colours could lead to perceptual grouping, even tho...
Article
2 we have now done a larger trial of mirror therapy on patients with hemiparesis following stroke. All patients were at least 6 months post-stroke proven by computed tomography or magnetic resonance imaging (mean 4·8 years post-stroke, SD 8·2 years, range 6 months to 26·25 years), to preclude effects from spontaneous recovery. The patients gave wri...
Article
Patient PH developed retinitis pigmentosa in childhood and progressively lost his vision until he became completely blind at 40 years old. At age 42, he started experiencing vivid ‘synesthesia’+ADs- tactile stimuli on the hand evoked a vivid visual sensation of ‘movement’, ‘expansion’ or ‘jumping’. Intriguingly, the synesthesia was much more vivid...
Article
Following right hemisphere stroke, many patients display an indifference to objects and events in the left side of the world ('neglect'). Here, we describe a new technique that might help accelerate recovery from neglect. The patient sits at a table and a mirror is propped vertically on the patient's right side in the parasagittal plane, so that wh...
Article
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We present a theory of human artistic experience and the neural mechanisms that mediate it. Any theory of art (or, indeed, any aspect of human nature) has to ideally have three components. (a) The logic of art: whether there are universal rules or principles; (b) The evolutionary rationale: why did these rules evolve and why do they have the form t...
Article
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Neurological syndromes in which consciousness seems to malfunction, such as temporal lobe epilepsy, visual scotomas, Charles Bonnet syndrome, and synesthesia offer valuable clues about the normal functions of consciousness and ‘qualia’. An investigation into these syndromes reveals, we argue, that qualia are different from other brain states in tha...
Article
When two spatially separated spots of light are flashed in rapid succession, apparent motion is seen between them. We extended this phenomenon by photographing a face and producing from it a fragmented `puzzle picture' or `Mooney face' in which the face is not initially visible (Fig. 1, left; frame 1) but is seen after 15 to 60 seconds. Another pho...
Article
We studied a patient after amputation of an arm and found that in less than 24 h stimuli applied on the ipsilateral face were referred in a precise, topographically organized, modality-specific manner to distinct points on the phantom. Functional magnetic resonance imaging (fMRI) performed one month later showed that brush-evoked activity in the br...

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