In this paper we investigate three approaches to iterated contraction, namely: the Moderate (or Priority) contraction, the Natural (or Conservative) contraction, and the Lexicographic contraction. We characterise these three contraction functions using certain, arguably plausible, properties of an iterated contraction function. While we provide the characterisation of the first two contraction operations using rationality postulates of the standard variety for iterated contraction, we found doing the same for the Lexicographic contraction more challenging. We provide its characterisation using a variation of (...) Epistemic ranking function instead. (shrink)
Probabilistic belief contraction has been a much neglected topic in the field of probabilistic reasoning. This is due to the difficulty in establishing a reasonable reversal of the effect of Bayesian conditionalization on a probabilistic distribution. We show that indifferent contraction, a solution proposed by Ramer to this problem through a judicious use of the principle of maximum entropy, is a probabilistic version of a full meet contraction. We then propose variations of indifferent contraction, using both the Shannon entropy measure (...) as well as the Hartley entropy measure, with an aim to avoid excessive loss of beliefs that full meet contraction entails. (shrink)
A t ﬁrst glance you might not noorder, which afﬂicts about 0.5 percent of tice anything odd on meeting a American children. Neither researcher young boy with autism. But if had any knowledge of the other’s work, you try to talk to him, it will and yet by an uncanny coincidence each quickly become obvious that gave the syndrome the same name: autism, something is seriously wrong. He may not which derives from the Greek word autos, make eye contact with (...) you; instead he may meaning “self.” The name is apt, because avoid your gaze and ﬁdget, rock his body the most conspicuous feature of the disorto and fro, or bang his head against the der is a withdrawal from social interacwall. More disconcerting, he may not be tion. More recently, doctors have adopted able to conduct anything remotely resemthe term “autism spectrum disorder” to bling a normal conversation. Even though make it clear that the illness has many rehe can experience emotions such as fear, lated variants that range widely in severity rage and pleasure, he may lack genuine but share some characteristic symptoms. empathy for other people and be oblivious Ever since autism was identiﬁed, reto subtle social cues that most children searchers have struggled to determine would pick up effortlessly. what causes it. Scientists know that sus- In the 1940s two physicians—Americeptibility to autism is inherited, although.. (shrink)
We present a theory of human artistic experience and the neural mechanisms that mediate it. Any theory of art has to ideally have three components. The logic of art: whether there are universal rules or principles; The evolutionary rationale: why did these rules evolve and why do they have the form that they do; What is the brain circuitry involved? Our paper begins with a quest for artistic universals and proposes a list of ‘Eight laws of artistic experience’ -- a (...) set of heuristics that artists either consciously or unconsciously deploy to optimally titillate the visual areas of the brain. One of these principles is a psychological phenomenon called the peak shift effect: If a rat is rewarded for discriminating a rectangle from a square, it will respond even more vigorously to a rectangle that is longer and skinnier that the prototype. We suggest that this principle explains not only caricatures, but many other aspects of art. Example: An evocative sketch of a female nude may be one which selectively accentuates those feminine form-attributes that allow one to discriminate it from a male figure; a Boucher, a Van Gogh, or a Monet may be a caricature in ‘colour space’ rather than form space. Even abstract art may employ ‘supernormal’ stimuli to excite form areas in the brain more strongly than natural stimuli. Second, we suggest that grouping is a very basic principle. The different extrastriate visual areas may have evolved specifically to extract correlations in different domains , and discovering and linking multiple features into unitary clusters -- objects -- is facilitated and reinforced by direct connections from these areas to limbic structures. In general, when object-like entities are partially discerned at any stage in the visual hierarchy, messages are sent back to earlier stages to alert them to certain locations or features in order to look for additional evidence for the object . Finally, given constraints on allocation of attentional resources, art is most appealing if it produces heightened activity in a single dimension rather than redundant activation of multiple modules. This idea may help explain the effectiveness of outline drawings and sketches, the savant syndrome in autists, and the sudden emergence of artistic talent in fronto-temporal dementia. In addition to these three basic principles we propose five others, constituting a total of ‘eight laws of aesthetic experience’. (shrink)
(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 visible. Taken collectively, these and other experiments prove conclusively that synaesthesia is a genuine percep- tual phenomenon, not an effect based on memory associations from childhood or on vague metaphorical speech. We identify different subtypes of number–colour synaesthesia (...) and propose that they are caused by hyperconnectivity between col- our and number areas at different stages in processing; lower synaesthetes may have cross-wiring (or cross-activation) within the fusiform gyrus, whereas higher synaesthetes may have cross-activation in the angular gyrus. This hyperconnec- tivity might be caused by a genetic mutation that causes defective pruning of con- nections between brain maps. The mutation may further be expressed selectively (due to transcription factors) in the fusiform or angular gyri, and this may explain the existence of different forms of synaesthesia. If expressed very diffusely, there may be extensive cross-wiring between brain regions that represent abstract concepts, which would explain the link between creativity, metaphor and synaesthesia (and the higher incidence of synaesthesia among artists and poets). Also, hyperconnectivity between the sensory cortex and amygdala would explain the heightened aversion synaesthetes experience when seeing numbers printed in the ‘wrong’ colour. Lastly, kindling (induced hyperconnectivity in the temporal lobes of temporal lobe epilepsy [TLE] patients) may explain the purported higher incidence of synaesthesia in these patients. We conclude with a synaesthesia-based theory. (shrink)
Subjects perceived touch sensations as arising from a table (or a rubber hand) when both the table (or the rubber hand) and their own real hand were repeatedly tapped and stroked in synchrony with the real hand hidden from view. If the table or rubber hand was then ‘injured’, subjects displayed a strong skin conductance response (SCR) even though nothing was done to the real hand. Sensations could even be projected to anatomically impossible locations. The illusion was much less vivid, (...) as indicated by subjective reports and SCR, if the real hand was simultaneously visible during stroking, or if the real hand was hidden but touched asynchronously. The fact that the illusion could be significantly diminished when the real hand was simultaneously visible suggests that the illusion and associated SCRs were due to perceptual assimilation of the table (or rubber hand) into one’s body image rather than associative conditioning. These experiments demonstrate the malleability of body image and the brain’s remarkable capacity for detecting statistical correlations in the sensory input. (shrink)
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.
The mechanism by which humans perceive others differs greatly from how humans perceive inanimate objects. Unlike inanimate objects, humans have the distinct property of being “like me” in the eyes of the observer. This allows us to use the same systems that process knowledge about self-performed actions, self-conceived thoughts, and self-experienced emotions to understand actions, thoughts, and emotions in others. The authors propose that internal simulation mechanisms, such as the mirror neuron system, are necessary for normal development of recognition, imitation, (...) theory of mind, empathy, and language. Additionally, the authors suggest that dysfunctional simulation mechanisms may underlie the social and communicative deficits seen in individuals with autism spectrum disorders. (shrink)
We studied two otherwise normal, synaesthetic subjects who `saw' a speci¢c colour every time they saw a speci¢c 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 though the inducing numerals or letters did not. (ii)Synaesthetically induced colours were not experienced if the graphemes were presented peripherally. (iii)Roman numerals were ine¡ective: the actual number grapheme was (...) required. (iv)If two graphemes were alternated the induced colours were also seen in alternation. However, colours were no longer experienced if the graphemes were alternated at more than 4 Hz. We propose that grapheme colour synaesthesia arises from `cross-wiring' between the `colour centre' (area V4 or V8)and the `number area', both of which lie in the fusiform gyrus. We also suggest a similar explanation for the representation of metaphors in the brain: hence, the higher incidence of synaesthesia among artists and poets. (shrink)
In Knowledge and Its Limits Timothy Williamson argues against the luminosity of phenomenal states in general by way of arguing against the luminosity of feeling cold, that is, against the view that if one feels cold, one is at least in a position to know that one does. In this paper I consider four strategies that emerge from his discussion, and argue that none succeeds.
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 that they possess three functional characteristics, which we state in the form of ‘three laws of qualia’. First, they are irrevocable: I cannot simply decide to start seeing the sunset as green, or (...) feel pain as if it were an itch; second, qualia do not always produce the same behaviour: given a set of qualia, we can choose from a potentially infinite set of possible behaviours to execute; and third, qualia endure in short-term memory, as opposed to non-conscious brain states involved in the on-line guidance of behaviour in real time. We suggest that qualia have evolved these and other attributes because of their role in facilitating non-automatic, decision-based action. We also suggest that the apparent epistemic barrier to knowing what qualia another person is experiencing can be overcome by using a ‘bridge’ of neurons; and we offer a hypothesis about the relation between qualia and one's sense of self. (shrink)
Patients with right parietal lesions often deny their paralysis , but do they have "tacit" knowledge of their paralysis? I devised three novel tests to explore this. First, the patients were given a choice between a bimanual task vs a unimanual one . They chose the former on 17 of 18 trials and, surprisingly, showed no frustration or learning despite repeated failed attempts. I conclude that they have no tacit knowledge of paralysis . Second, I used a "virtual reality box" (...) to convey the optical illusion to the patient that she was moving her paralyzed left hand up and down to the rhythm of a metronome, and yet she showed no sign of surprise. Third, I irrigated patient BM′s left ear canal with cold water, a procedure that is known to shift that patient′s spatial frame of reference by stimulating the vestibular system. Surprisingly, this allowed her "repressed" memory of paralysis to come to the surface; she said she had been paralyzed continuously for several days. I suggest that the vestibular stimulation produces these remarkable effects by mimicking REM sleep. These patients also emply a whole arsenal of grossly exaggerated Freudian "defense mechanisms" to account for their paralysis. To explain this, I propose that in normal individuals the left hemisphere ordinarily deals with small, local anomalies by trying to impose consistency but, when the anomaly exceeds threshold, an interaction with the right hemisphere forces a "paradigm shift". A failure of this process, in patients with right hemisphere damage, might partially account for anosognosia. Finally, I present a new conceptual framework that may help link several psychological and neurological phenomena such as Freudian defense mechanisms, vestibular stimulation, anosognosia, memory repression, visual illusions, anterograde amnesia, REM sleep, dreaming, and humor. (shrink)
On David Lewis's original analysis of causation, c causes e only if c is linked to e by a chain of distinct events such that each event in the chain (counter-factually) depends on the former one. But this requirement precludes the possibility of late pre-emptive causation, of causation by fragile events, and of indeterministic causation. Lewis proposes three different strategies for accommodating these three kinds of cases, but none of these turn out to be satisfactory. I offer a single analysis (...) of causation that resolves these problems in one go but which respects Lewis's initial insights. One distinctive feature of my account is that it accommodates indeterministic causation without resorting to probabilities. (shrink)
Summary 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 psychotic or delusional, however, they do express an inexplicable emotional abhorrence to the limb they wish removed. It is also known that such (...) patients show a left-sided preponderance for their desired amputation. Often they take drastic action to be rid of the offending limb. Given the left-sided bias, emotional rejection and specificity of desired amputation, we suggest that there are clear similarities to be drawn between BIID and somatoparaphrenia. In this rare condition, which follows a right parietal stroke, the patient rejects (usually) his left arm as ‘‘alien’’. We go on to hypothesis that a dysfunction of the right parietal lobe is also the cause of BIID. We suggest that this leads to an uncoupling of the construct of one’s body image in the right parietal lobe from how one’s body physically is. This hypothesis would be amenable to testing by response to cold-water vestibular caloric stimulation, which is known to temporarily treat somatoparaphrenia. It could also be investigated using functional brain imaging and skin conductance response. If correct our hypothesis not only suggests why BIID arises, but also, in caloric stimulation a therapeutic avenue for this chronic and essentially untreatable condition. (shrink)
Jones and Coleman are among a handful of otherwise normal as a child and the number 5 was red and 6 was green. This the- people who have synesthesia. They experience the ordinary ory does not answer why only some people retain such vivid world in extraordinary ways and seem to inhabit a mysterious sensory memories, however. You might _think _of cold when you no-man’s-land between fantasy and reality. For them the sens- look at a picture of an ice cube, (...) but you probably do not feel es—touch, taste, hearing, vision and smell—get mixed up in- cold, no matter how many encounters you may have had with stead of remaining separate. ice and snow during your youth. Modern scientists have known about synesthesia since Another prevalent idea is that synesthetes are merely being 1880, when Francis Galton, a cousin of Charles Darwin, pub- metaphorical when they describe the note C ﬂat as “red” or say lished a paper in _Nature _on the phenomenon. But most have that chicken tastes “pointy”—just as you and I might speak of brushed it aside as fakery, an artifact of drug use (LSD and a “loud” shirt or “sharp” cheddar cheese. Our ordinary lan- mescaline can produce similar effects) or a mere curiosity. guage is replete with such sense-related metaphors, and perhaps About four years ago, however, we and others began to un- synesthetes are just especially gifted in this regard. cover brain processes that could account for synesthesia. Along We began trying to ﬁnd out whether synesthesia is a gen- the way, we also found new clues to some of the most mysteri- uine sensory experience in 1999. This deceptively simple ques- ous aspects of the human mind, such as the emergence of ab- tion had plagued researchers in this ﬁeld for decades. One nat- stract thought, metaphor and perhaps even language. ural approach is to start by asking the subjects outright: “Is this A common explanation of synesthesia is that the affected just a memory, or do you actually see the color as if it were right people are simply experiencing childhood memories and asso- in front of you?” When we tried asking this question, we did ciations.. (shrink)
Anydomainofscientificresearchhasitssustainingorthodoxy. Thatis, research on a problem, whether in astronomy, physics, or biology, is con- ducted against a backdrop of broadly shared assumptions. It is these as- sumptionsthatguideinquiryandprovidethecanonofwhatisreasonable-- of what "makes sense." And it is these shared assumptions that constitute a framework for the interpretation of research results. Research on the problem of how we see is likewise sustained by broadly shared assump- tions, where the current orthodoxy embraces the very general idea that the business of the visual system is to (...) create a detailed replica of the visual world, and that it accomplishes its business via hierarchical organization and by operatingessentiallyindependently of other sensorymodalitiesas well as independently of previous learning, goals, motor planning, and motor execution. (shrink)
The leading idea of this article is that one cannot acquire knowledge of any non-epistemic fact by virtue of knowing that one that knows something. The lines of reasoning involved in the surprise exam paradox and in Williamson’s _reductio_ of the KK-principle, which demand that one can, are thereby undermined, and new type of counter-example to epistemic closure emerges.
Hempel‘s paradox of the ravens, and his take on it, are meant to be understood as being restricted to situations where we have no additional background information. According to him, in the absence of any such information, observations of FGs confirm the hypothesis that all Fs are G. In this paper I argue against this principle by way of considering two other paradoxes of confirmation, Goodman‘s 'grue‘ paradox and the 'tacking‘ (or 'irrelevant conjunct‘) paradox. What these paradoxes reveal, I argue, (...) is that a presumption of causal realism is required to ground any confirmation; but once we grant causal realism, we have no reason to accept the central principles giving rise to the paradoxes. (shrink)
Apotemnophilia, a disorder that blurs the distinction between neurology and psychiatry, is characterized by the intense and longstanding desire for amputation of a speci¢c limb. Here we present evidence from two individuals suggestive that this condition, long thought to be entirely psychological in origin, actually has a neurological basis. We found heightened skin conductance response..
Here we outline a simple method of using two mirrors which allows one to stand outside oneself. This method demonstrates that registration of vision with touch and proprioception is crucial for the perception of the corporeal self. Our method may also allow the disassociation of taste from touch, proprioception, and movement.
A slight modification to the translation scheme for David Lewis's counterpart theory I put forward in 'An Alternative Translation Scheme for Counterpart Theory' (Analysis 49.3 (1989)) is proposed. The motivation for this change is that it makes for a more plausible account of contingent identity. In particular, contingent identity is accommodated without admitting the contingency of self-identity.
In his influential paper 'Speaker's Reference and Semantic Reference', Kripke defends Russell's theory of descriptions against the charge that the existence of referential and attributive uses of descriptions reflects a semantic ambiguity. He presents a purely defensive argument to show that Russell's theory is not refuted by the referential usage and a number of methodological considerations which apparently tell in favour of Russell's unitary theory over an ambiguity theory. In this paper, I put forward a case for the ambiguity theory (...) that thwarts Kripke's defensive strategy and argue that it is not undermined by any of his methodological points. (shrink)
This paper considers, and rejects, three strategies aimed at showing that the KK-principle fails even in most favourable circumstances (all emerging from Williamson’s Knowledge and its Limits ). The case against the final strategy provides positive grounds for thinking that the principle should hold good in such situations.
Murali Ramachandran has kindly provided me with four (alleged) counterexamples to the theory of causation which I recently put forward in Mind (Ramachandran 2000; Noordhof 1999). Space is limited for a response. Since this note will be published Ramachandran's paper, I will not set out the cases he gives. I refer the reader to the appropriate descriptions. I will also presume knowledge of the framework of my paper and just give page references in case this is helpful. (...) I will try to couch the discussion with as little reference to the technical apparatus of my paper as possible. Maybe the ideas will stand out more clearly that way. (shrink)
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 that they possess three functional characteristics, which we state in the form of ‘three laws of qualia ’ based on a loose analogy with Newton’s three laws of classical mechanics. First, they are (...) irrevocable: I cannot simply decide to start seeing the sunset as green, or feel pain as if it were an itch; second, qualia do not always produce the same behaviour: given a set of qualia, we can choose from a potentially infinite set of possible behaviours to execute; and third, qualia endure in short-term memory, as opposed to non-conscious brain states involved in the on-line guidance of behaviour in real time. We suggest that qualia have evolved these and other attributes (e.g. they are ‘filled in’) because of their role in facilitating non-automatic, decision-based action. We also suggest that the apparent epistemic barrier to knowing what qualia another person is experiencing can be overcome simply by using a ‘bridge ’ of neurons; and we offer a hypothesis about the relation between qualia and one’s sense of self. (shrink)
Summary 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 bodies to the sex they feel they should have been born. The vivid sensation of still having a limb although it has been amputated, a phantom (...) limb, was first described by Weir Mitchell over a century ago. The same phenomenon is also occurs after amputation of the penis or a breast. Around 60% of men who have had to have their penis amputated for cancer will experience a phantom penis. It has recently been shown that a significant factor in these phantom sensations is ‘‘cross-activation’’ between the de-afferented cortex and surrounding areas. Despite this it also known that much of our body image is innately ‘‘hard-wired’’ into our brains; congenitally limbless patients can still experience phantom sensations. We hypothesise that, perhaps due to a dissociation during embryological development, the brains of transsexuals are ‘‘hard-wired’’ in manner, which is opposite to that of their biological sex. We go on to predict that male-to-female transsexuals will be much less likely to experience a phantom penis than a ‘‘normal’’ man who has had his penis amputated for another reason. The same will be true of female-to-male transsexuals who have had breast removal surgery. We also predict that some female-to-male transsexuals will have a phantom penis even although there is not one physically there. We believe that this is an easily testable hypothesis, which, if correct, would offer insights into both the basis of transsexuality and provide farther evidence that we have a gender specific body image, with a strong innate component that is ‘‘hard-wired’’ into our brains. This would furnish us with a better understanding the mechanism by which nature and nurture interact to link the brain-based internal body image with external sexual morphology.. (shrink)
This paper examines a neglected puzzle about conditionals: namely, the fact that each of a pair of conditionals with incompatible consequents, [A > C] and [B > C*], may be properly affirmable in circumstances when one does not believe, and is not entitled to infer, the denial of the conjunction of the antecedents, i.e. ~(A & B). The puzzle is why this should be so, since the conditionals entail the conjunction on the popular accounts of conditionals. I present a pragmatic (...) solution which distinguishes between two levels of affirmability. (shrink)
Nanomedicine is a rapidly growing field in the academic as well as commercial arena. While some had predicted nanomedicine sales to reach $20.1 billion in 2011, the actual growth was much more rapid, with the global nanomedicine market being valued at $53 billion in 2009, and forecast to increase at an annual growth rate of 13.5% to reach more than $100 billion in 2014. In 2006, more than 130 nanotechnology-based drugs and delivery systems had entered preclinical, clinical, or commercial development. (...) The European Medicines Agency reviewed 18 marketing authorization applications for nanomedicines in 2010. In 2011, 22 drugs that had been approved by the FDA, and 87 Phase I and Phase II clinical trials were listed in the U.S. National Institutes of Health data base, www.clinicaltrials.gov. Although the fastest growing areas of nanomedicine are applications in medical imaging and diagnosis using contrast-enhancing agents, most nanomedicine research and commercialization is in the area of cancer drug therapy, including nano gold shells. (shrink)
Tracking accounts of knowledge were originally motivated by putative counter-examples to epistemic closure. But, as is now well known, these early accounts have many highly counterintuitive consequences. In this note, I motivate a tracking-based account which respects closure but which resolves many of the familiar problems for earlier tracking account along the way.
David Lewis’s counterpart-theoretic semantics for quantified modal logic is motivated originally by worries about identifying objects across possible worlds; the counterpart relation is grounded more cautiously on comparative similarity. The possibility of contingent identity is an unsought -- and in some eyes, unwelcome -- consequence of this approach. In this paper I motivate a Kripkean counterpart theory by way of defending the prior, pre-theoretical, coherence of contingent directness. Contingent identity follows for free. The theory is Kripkean in that the counterpart (...) relation is in a sense stipulated rather than grounded on similarity, and is such that no object has more than one counterpart at a world. This avoids a number of objections Fara and Williamson have recently levelled against counterpart theory generally; their other objections are addressed by enriching the theory with special quantifiers and actuality operators. (shrink)
The article focuses on issues relating to occupational exposures of researchers and lab workers, and exposures of bystanders such as health care workers and family members during HSR using nanomaterials. Such third-party exposures give rise to unique challenges relating to oversight as well as exposures to worker groups not previously studied. Given the current state of knowledge regarding health risks from such exposures, a more precautionary approach to oversight seems advisable.
Although a number of studies have demonstrated that perceived ethical leadership engenders beneficial follower outcomes, there is a dearth of research on ethical leadership in the sales context. This is surprising given that salespersons constantly face ethical challenges in their work environment and ethical leadership could provide them with appropriate guidelines for navigating such challenges successfully. Focusing on the salesperson’s perspective and responding to calls for investigating underlying processes responsible for the effects of ethical leadership, this study proposes that sales (...) managers’ ethical leadership influences salespersons’ emulation intentions—i.e., their intentions to model or imitate the manager’s ethical behavior—which, in turn, influences both behavior and outcome performance. In addition, salespersons’ perceptions of the manager’s competence and gratitude toward the manager are examined as moderating mechanisms on the relationship between ethical leadership and salespersons’ emulation. Finally, three aspects of the ethical climate prevailing in the organization—ethical responsibility, peers’ unethical behavior, and unethical sales practices—are included as control variables. The proposed relationships are tested by using data from 290 business-to-business salespeople. Based on the findings, implications are offered for theory and practice. (shrink)