In amblyopia, abnormal visual experience during development leads to an enduring loss of visual acuity in adulthood. Physiological studies in animal models suggest that intracortical GABAergic inhibition may mediate visual deficits in amblyopia. To better understand the relationship between visual cortical γ-aminobutyric acid (GABA) and perceptual suppression in persons with amblyopia (PWA), we employed magnetic resonance spectroscopy (MRS) to quantify GABA levels in both PWA and normally-sighted persons (NSP). In the same individuals, we obtained psychophysical measures of perceptual suppression for (...) a variety of ocular configurations. In PWA, we found a robust negative correlation between the depth of amblyopia (the difference in visual acuity between the amblyopic and non-amblyopic eyes) and GABA concentration that was specific to visual cortex and was not observed in a sensorimotor cortical control region. Moreover, lower levels of visual cortical GABA were associated with weaker perceptual suppression of the fellow eye by the amblyopic eye and stronger suppression of the amblyopic eye by the fellow eye. Taken together, our findings provide evidence that intracortical GABAergic inhibition is an important component of the pathology of human amblyopia and suggest possible therapeutic interventions to restore vision in the amblyopic eye through enhancement of visual cortical GABAergic signaling in PWA. (shrink)

The theory of mental models and its computer implementations have led to crucial experiments showing that no standard logic—the sentential calculus and all logics that include it—can underlie human reasoning. The theory replaces the logical concept of validity (the conclusion is true in all cases in which the premises are true) with necessity (conclusions describe no more than possibilities to which the premises refer). Many inferences are both necessary and valid. But experiments show that individuals make necessary inferences that are (...) invalid, e.g., Few people ate steak or sole; therefore, few people ate steak. Other crucial experiments show that individuals reject inferences that are not necessary but valid, e.g., He had the anesthetic or felt pain, but not both; therefore, he had the anesthetic or felt pain, or both. Nothing in logic can justify the rejection of a valid inference: a denial of its conclusion is inconsistent with its premises, and inconsistencies yield valid inferences of any conclusions whatsoever including the one denied. So inconsistencies are catastrophic in logic. In contrast, the model theory treats all inferences as defeasible (nonmonotonic), and inconsistencies have the null model, which yields only the null model in conjunction with any other premises. So inconsistences are local. Which allows truth values in natural languages to be much richer than those that occur in the semantics of standard logics; and individuals verify assertions on the basis of both facts and possibilities that did not occur. (shrink)

How do people make deductions? The orthodox view in psychology is that they use formal rules of inference like those of a “natural deduction” system.Deductionargues that their logical competence depends, not on formal rules, but on mental models. They construct models of the situation described by the premises, using their linguistic knowledge and their general knowledge. They try to formulate a conclusion based on these models that maintains semantic information, that expresses it parsimoniously, and that makes explicit something not directly (...) stated by any premise. They then test the validity of the conclusion by searching for alternative models that might refute the conclusion. The theory also resolves long-standing puzzles about reasoning, including how nonmonotonic reasoning occurs in daily life. The book reports experiments on all the main domains of deduction, including inferences based on prepositional connectives such as “if” and “or,” inferences based on relations such as “in the same place as,” inferences based on quantifiers such as “none,” “any,” and “only,” and metalogical inferences based on assertions about the true and the false. Where the two theories make opposite predictions, the results confirm the model theory and run counter to the formal rule theories. Without exception, all of the experiments corroborate the two main predictions of the model theory: inferences requiring only one model are easier than those requiring multiple models, and erroneous conclusions are usually the result of constructing only one of the possible models of the premises. (shrink)

We resolve the two problems that Hardman raises. The first problem arises from a misunderstanding: the crucial distinction is between one-model and multiple-model problems. The second problem illuminates a deeper principle: conclusions depend on the procedures for interpreting models. We describe an algorithm that obviates the problem and empirical work that reveals a new view of syllogistic reasoning.

Van der Henst argues that the theory of mental models lacks a pragmatic component. He fills the gap with the notion that reasoners draw the most relevant conclusions. We agree, but argue that theories need an element of “nondeterminism.” It is often impossible to predict either what will be most relevant or which particular conclusion an individual will draw.

Randomized control trials (RCTs) are the gold standard for estimating causal effects, but often use samples that are non-representative of the actual population of interest. We propose a reweighting method for estimating population average treatment effects in settings with noncompliance. Simulations show the proposed compliance-adjusted population estimator outperforms its unadjusted counterpart when compliance is relatively low and can be predicted by observed covariates. We apply the method to evaluate the effect of Medicaid coverage on health care use for a target (...) population of adults who may benefit from expansions to the Medicaid program. We draw RCT data from the Oregon Health Insurance Experiment, where less than one-third of those randomly selected to receive Medicaid benefits actually enrolled. (shrink)

This paper replies to Politzer’s (2007) criticisms of the mental model theory of conditionals. It argues that the theory provides a correct account of negation of conditionals, that it does not provide a truth-functional account of their meaning, though it predicts that certain interpretations of conditionals yield acceptable versions of the ‘paradoxes’ of material implication, and that it postulates three main strategies for estimating the probabilities of conditionals.

Recent developments in genomic science hold out the tantalizing prospect of soon being able to treat and prevent a wide variety of medical conditions through gene therapy. In time, it may be possible to use similar techniques not simply to combat disease but also to enhance, or improve on, normal human functioning.

Recent developments in genomic science hold out the tantalizing prospect of soon being able to treat and prevent a wide variety of medical conditions through gene therapy. In time, it may be possible to use similar techniques not simply to combat disease but also to enhance, or improve on, normal human functioning.

Tom Beauchamp and James Childress have always maintained that their four principles approach (otherwise known as principlism) is a globally applicable framework for biomedical ethics. This claim is grounded in their belief that the principles of respect for autonomy, non-maleficence, beneficence and justice form part of a 'common morality', or collection of very general norms to which everyone who is committed to morality subscribes. The difficulty, however, has always been how to demonstrate, at least in the absence of a full-blooded (...) analysis of the concept of morality, whether the four principles are foundational, and so globally applicable, in this way. In the recently published sixth edition of Principles of Biomedical Ethics, an imaginative and non-question-begging empirical method of determining the common morality's norms is suggested. In this paper, I outline this method, before arguing that it is difficult to see how it might be thought to achieve its purpose. (shrink)

Recent developments in genomic science hold out the tantalizing prospect of soon being able to treat and prevent a wide variety of medical conditions through gene therapy. In time, it may be possible to use similar techniques not simply to combat disease but also to enhance, or improve on, normal human functioning.

This chapter aims to show that prospective parents are not bound in their reproductive decision making by a principle of procreative beneficence. That is, they have no obligation (as Julian Savulescu, the principle’s originator, famously thinks they have) to choose the possible child, from a range of possible children they might have, who is likely to lead the best life. I will summarise and clarify the content of previous papers of mine, in which I argue that since the sorts of (...) considerations that underlie the principle of procreative beneficence do not constitute reasons when viewed from a perspective that it is fitting and appropriate for a prospective parent to take up, there can be no requirement for prospective parents to be moved by those considerations. (shrink)

Recent political turmoil has focused international attention on Egypt, yet there is little awareness of the country’s stateless populations—those who lack legal nationality to any state—or the challenges they face. Individuals in situations of protracted statelessness are denied their right to a nationality, resulting in an array of additional rights violations. Such violations include denied freedom of movement, equality before the law, and access to economic and social rights. Drawing from two years’ of fieldwork data, this study highlights the plight (...) of those who are unable to achieve legal status in a country with harsh punishments for illegal presence, entry, and exit. It also evaluates potential solutions for eliminating statelessness in Egypt and protecting the rights of stateless populations. As Egypt seeks to move beyond revolution, it is vital that the government addresses the pervasive and systemic inequalities that deny individuals their right to a nationality. (shrink)

This article presents a fundamental advance in the theory of mental models as an explanation of reasoning about facts, possibilities, and probabilities. It postulates that the meanings of compound assertions, such as conditionals (if) and disjunctions (or), unlike those in logic, refer to conjunctions of epistemic possibilities that hold in default of information to the contrary. Various factors such as general knowledge can modulate these interpretations. New information can always override sentential inferences; that is, reasoning in daily life is defeasible (...) (or nonmonotonic). The theory is a dual process one: It distinguishes between intuitive inferences (based on system 1) and deliberative inferences (based on system 2). The article describes a computer implementation of the theory, including its two systems of reasoning, and it shows how the program simulates crucial predictions that evidence corroborates. It concludes with a discussion of how the theory contrasts with those based on logic or on probabilities. (shrink)

In recent decades, scientists have begun to identify the brain processes and neurochemicals associated with the different stages of love, including the all-important stage of attachment. Experimental findings—readily seized upon by those bioethicists who want to urge that we sometimes have good reason pharmaceutically to enhance flagging relationships—are presented as demonstrating that attachment is regulated and strengthened by the neuropeptides oxytocin and vasopressin. I shall argue, however, that often what the experimental data in fact show is only that exogenous administration (...) of such chemicals can control and intensify the trappings of attachment, not attachment itself. That this is sometimes overlooked by both scientists and ethicists, is due to attachment being miscategorised as a set of feelings or a drive, rather than as a disposition to think about, feel toward, and behave toward its object in certain distinctive ways. (shrink)

Two experiments investigated inferences based on suppositions. In Experiment 1, the subjects decided whether suppositions about individuals' veracity were consistent with their assertions—for example, whether the supposition “Ann is telling the truth and Beth is telling a lie”, is consistent with the premises: “Ann asserts: I am telling the truth and Beth is telling the truth. Beth asserts: Ann is telling the truth”. It showed that these inferences are more difficult than ones based on factual premises: “Ann asserts: I live (...) in Dublin and Beth lives in Dublin”. There was no difference between problems about truthtellers and liars, who always told the truth or always lied, and normals, who sometimes told the truth and sometimes lied. In Experiment 2, the subjects made inferences about factual matters set in three contexts: a truth-inducing context in which friends confided their personality characteristics, a lie-inducing context in which business rivals advertised their products, and a neutral context in which computers printed their program characteristics. Given the supposition that the individuals were lying, it was more difficult to make inferences in a truth-inducing context than in the other two contexts. We discuss the implications of our results for everyday reasoning from suppositions, and for theories of reasoning based on models or inference rules. (shrink)

Sober (1992) has recently evaluated Brandon's (1982, 1990; see also 1985, 1988) use of Salmon's (1971) concept of screening-off in the philosophy of biology. He critiques three particular issues, each of which will be considered in this discussion.

Two recently published oral histories highlight the long-term trend concerning the mainstreaming of Objectivism, the political and economic ideas of the libertarian conservative writer and ideologue, Ayn Rand. Scott McConnell’s sympathetic interview collection focuses on supporters and acquaintances from Rand’s active period in the 1960s and 1970s. These supporters and acquaintances include former Australian Prime Minister, Malcolm Fraser, who provides McConnell with his considered views concerning Rand. Gary Weiss’s critical interview collection focusses on her more recent supporters, with one displeased (...) and insightful interviewee to be found in both collections. Weiss’s collection reveals the role played by Objectivists in galvanizing the focus of the populist Tea Party movement. Both oral histories reveal the role played by the media and popular culture in mainstreaming Rand’s views. The review ends by comparing Randolph Stow’s socially responsive individualism as described in his novel 'Tourmaline' with Rand’s transactional individualism as described in 'Atlas Shrugged.'. (shrink)

The Scottish Mental Health Arts and Film Festival has seen hundreds of arts, public and community groups coproduce over 300 events to over 25,000 audience members. Integral to this arts-based approach, in contrast to social marketing or public education models, is the notion that mental health is an essentially contested concept whereby meanings are negotiated and debate encouraged. With emerging evidence that the festival is an ef ective way of engaging people intellectually and emotionally, we explore ethical issues, challenges and (...) paradoxes that have emerged as the festival has developed. Consideration is given to issues of power, purpose, opportunity costs, reach, impact, programming risks, and participation from those with experience of mental ill-health. Throughout, we explore practical implications for funding, managing, programming, marketing and evaluation of this and similar endeavours. (shrink)

Jonardon Ganeri, Paul Noordhof, and Murali Ramachandran (1996) have proposed a new counterfactual analysis of causation. We argue that this – the PCA-analysis – is incorrect. In section 1, we explain David Lewis’s first counterfactual analysis of causation, and a problem that led him to propose a second. In section 2 we explain the PCA-analysis, advertised as an improvement on Lewis’s later account. We then give counterexamples to the necessity (section 3) and sufficiency (section 4) of the PCA-analysis.

A critical analysis of contemporary strategic management theory and practice suggests that modernist, linear thinking has facilitated the development of an abstracted reality which is misleading to managers and fundamentally flawed. It is argued that formulaic strategic tools such as those propounded by Porter fail to capture the reality of the complex environments that confront firms and falsely suggest that an answer can be derived from a predetermined toolbox. As an alternative to this dominant paradigm, the complexity of markets is (...) presented not as something to be feared and ignored, but rather as a truth to be embraced. As a basis of taking this step, current knowledge on how complex environments work, perspectives on how they can be better understood and how people and organizations can engage within them, is presented. Ultimately it is recognised that both theoretical and practical foundations need significant, further development. (shrink)

The United States is in its fifth year of what is now widely referred to as “the new medical malpractice crisis.” Although some professional liability insurers have begun to report improvements in their overall financial margins, there are few signs that the trend toward higher costs is reversing itself - particularly for doctors and hospitals. In 2003-2004, the presidential election and tort reform proposals in Congress brought heightened public attention to the need for some type of policy intervention to ease (...) the effects of the crisis.The darling of tort reformers at both the federal and state levels has been legislation to limit, or “cap,” damages awarded to plaintiffs in malpractice cases. Health care provider groups, liability insurers, and the Bush Administration have all seized on the example of California's MICRA law, which since 1975 has capped noneconomic damages in malpractice cases at a flat $250,000, as the path to financial recovery. (shrink)

The United States is in its fifth year of what is now widely referred to as “the new medical malpractice crisis.” Although some professional liability insurers have begun to report improvements in their overall financial margins, there are few signs that the trend toward higher costs is reversing itself - particularly for doctors and hospitals. In 2003-2004, the presidential election and tort reform proposals in Congress brought heightened public attention to the need for some type of policy intervention to ease (...) the effects of the crisis.The darling of tort reformers at both the federal and state levels has been legislation to limit, or “cap,” damages awarded to plaintiffs in malpractice cases. Health care provider groups, liability insurers, and the Bush Administration have all seized on the example of California's MICRA law, which since 1975 has capped noneconomic damages in malpractice cases at a flat $250,000, as the path to financial recovery. (shrink)

Identifying corporate governance mechanisms to improve firm performance has been at the forefront of policy discussion and research in recent years. Existing research in this area focuses on large-capitalisation firms, and has not provided much insight on smaller firms. This paper tests for the optimality of deployment of governance mechanisms for Canadian small-cap firms by estimating a simultaneous equation system that links four control mechanisms to firm performance, using recent data. The results confirm simultaneity between several governance mechanisms and Canadian (...) small-cap firm performance. CEO ownership and shareholder rights are shown to determine board independence. CEO ownership in turn is shown to depend on the extent of shareholder rights and whether the CEO is also Chairperson of the board. Canadian small-cap firms appear to overutilise debt as a control mechanism. There is somewhat weaker evidence that board independence and CEO ownership are beyond the optimum. The latter, given the relatively high degree of CEO ownership in Canadian small-cap firms, is consistent with management entrenchment. We also do not find any significant discount to performance for Quebec-based firms, or for firms with dual or multiple voting class shares structures. (shrink)

Research shows that early scientific interest is associated with science degree completion and career selection. However, little is known about the conditions that support early scientific interest. Using a “funds of knowledge” theoretical framework, this study examined the role of parents, family, and extended social networks in fostering early interest in science. Using interview narratives from 116 scientists (physicists and chemists) in the United States, we conducted a qualitative thematic content analysis. Findings suggest that children who become scientists in adulthood (...) often received early, informal opportunities to use and manipulate material objects and discover how the world works. Second, families used a wide variety of scientific terms at home and encouraged children to pursue their interests whether in science or other fields. Third, these future scientists were often networked with extended family members or friends to observe and do science when they were quite young. Collectively, these findings highlight the specific ways in which families fostered early scientific interest and aided in supporting a student-directed learning environment. (shrink)