Shepard has argued that a universal law should govern generalization across different domains of perception and cognition, as well as across organisms from different species or even different planets. Starting with some basic assumptions about natural kinds, he derived an exponential decay function as the form of the universal generalization gradient, which accords strikingly well with a wide range of empirical data. However, his original formulation applied only to the ideal case of generalization from a single encountered stimulus to a (...) single novel stimulus, and for stimuli that can be represented as points in a continuous metric psychological space. Here we recast Shepard's theory in a more general Bayesian framework and show how this naturally extends his approach to the more realistic situation of generalizing from multiple consequential stimuli with arbitrary representational structure. Our framework also subsumes a version of Tversky's set-theoretic model of similarity, which is conventionally thought of as the primary alternative to Shepard's continuous metric space model of similarity and generalization. This unification allows us not only to draw deep parallels between the set-theoretic and spatial approaches, but also to significantly advance the explanatory power of set-theoretic models. Key Words: additive clustering; Bayesian inference; categorization; concept learning; contrast model; features; generalization; psychological space; similarity. (shrink)

Exploring how people represent natural categories is a key step toward developing a better understanding of how people learn, form memories, and make decisions. Much research on categorization has focused on artificial categories that are created in the laboratory, since studying natural categories defined on high-dimensional stimuli such as images is methodologically challenging. Recent work has produced methods for identifying these representations from observed behavior, such as reverse correlation (RC). We compare RC against an alternative method for inferring the structure (...) of natural categories called Markov chain Monte Carlo with People (MCMCP). Based on an algorithm used in computer science and statistics, MCMCP provides a way to sample from the set of stimuli associated with a natural category. We apply MCMCP and RC to the problem of recovering natural categories that correspond to two kinds of facial affect (happy and sad) from realistic images of faces. Our results show that MCMCP requires fewer trials to obtain a higher quality estimate of people’s mental representations of these two categories. (shrink)

In many learning or inference tasks human behavior approximates that of a Bayesian ideal observer, suggesting that, at some level, cognition can be described as Bayesian inference. However, a number of findings have highlighted an intriguing mismatch between human behavior and standard assumptions about optimality: People often appear to make decisions based on just one or a few samples from the appropriate posterior probability distribution, rather than using the full distribution. Although sampling-based approximations are a common way to implement Bayesian (...) inference, the very limited numbers of samples often used by humans seem insufficient to approximate the required probability distributions very accurately. Here, we consider this discrepancy in the broader framework of statistical decision theory, and ask: If people are making decisions based on samples—but as samples are costly—how many samples should people use to optimize their total expected or worst-case reward over a large number of decisions? We find that under reasonable assumptions about the time costs of sampling, making many quick but locally suboptimal decisions based on very few samples may be the globally optimal strategy over long periods. These results help to reconcile a large body of work showing sampling-based or probability matching behavior with the hypothesis that human cognition can be understood in Bayesian terms, and they suggest promising future directions for studies of resource-constrained cognition. (shrink)

People are adept at inferring novel causal relations, even from only a few observations. Prior knowledge about the probability of encountering causal relations of various types and the nature of the mechanisms relating causes and effects plays a crucial role in these inferences. We test a formal account of how this knowledge can be used and acquired, based on analyzing causal induction as Bayesian inference. Five studies explored the predictions of this account with adults and 4-year-olds, using tasks in which (...) participants learned about the causal properties of a set of objects. The studies varied the two factors that our Bayesian approach predicted should be relevant to causal induction: the prior probability with which causal relations exist, and the assumption of a deterministic or a probabilistic relation between cause and effect. Adults’ judgments (Experiments 1, 2, and 4) were in close correspondence with the quantitative predictions of the model, and children’s judgments (Experiments 3 and 5) agreed qualitatively with this account. (shrink)

Current psychological theories of human causal learning and judgment focus primarily on long-run predictions: two by estimating parameters of a causal Bayes nets, and a third through structural learning. This paper focuses on people’s short-run behavior by examining dynamical versions of these three theories, and comparing their predictions to a real-world dataset.

If Bayesian Fundamentalism existed, Jones & Love's (J&L's) arguments would provide a necessary corrective. But it does not. Bayesian cognitive science is deeply concerned with characterizing algorithms and representations, and, ultimately, implementations in neural circuits; it pays close attention to environmental structure and the constraints of behavioral data, when available; and it rigorously compares multiple models, both within and across papers. J&L's recommendation of Bayesian Enlightenment corresponds to past, present, and, we hope, future practice in Bayesian cognitive science.

The tendency to test outcomes that are predicted by our current theory (the confirmation bias) is one of the best-known biases of human decision making. We prove that the confirmation bias is an optimal strategy for testing hypotheses when those hypotheses are deterministic, each making a single prediction about the next event in a sequence. Our proof applies for two normative standards commonly used for evaluating hypothesis testing: maximizing expected information gain and maximizing the probability of falsifying the current hypothesis. (...) This analysis rests on two assumptions: (a) that people predict the next event in a sequence in a way that is consistent with Bayesian inference; and (b) when testing hypotheses, people test the hypothesis to which they assign highest posterior probability. We present four behavioral experiments that support these assumptions, showing that a simple Bayesian model can capture people's predictions about numerical sequences (Experiments 1 and 2), and that we can alter the hypotheses that people choose to test by manipulating the prior probability of those hypotheses (Experiments 3 and 4). (shrink)

Background Various authorities recommend the participation of patients in promoting patient safety, but little is known about health care professionals' (HCPs') attitudes towards patients' involvement in safety-related behaviours. Objective To investigate how HCPs evaluate patients' behaviours and HCP responses to patient involvement in the behaviour, relative to different aspects of the patient, the involved HCP and the potential error. Design Cross-sectional fractional factorial survey with seven factors embedded in two error scenarios (missed hand hygiene, medication error). Each survey included two (...) randomized vignettes that described the potential error, a patient's reaction to that error and the HCP response to the patient. Setting Twelve hospitals in Switzerland. Participants A total of 1141 HCPs (response rate 45%). Measurements Approval of patients' behaviour, HCP response to the patient, anticipated effects on the patient–HCP relationship, HCPs' support for being asked the question, affective response to the vignettes. Outcomes were measured on 7-point scales. Results Approval of patients' safety-related interventions was generally high and largely affected by patients' behaviour and correct identification of error. Anticipated effects on the patient–HCP relationship were much less positive, little correlated with approval of patients' behaviour and were mainly determined by the HCP response to intervening patients. HCPs expressed more favourable attitudes towards patients intervening about a medication error than about hand sanitation. Conclusions This study provides the first insights into predictors of HCPs' attitudes towards patient engagement in safety. Future research is however required to assess the generalizability of the findings into practice before training can be designed to address critical issues. (shrink)

L B Daniels; Some Comments on ‘Value in Education’ by Johanna Burgess1, Journal of Philosophy of Education, Volume 8, Issue 2, 30 May 2006, Pages 237–250, https.

Planned home birth has been considered by some to be consistent with professional responsibility in patient care. This article critically assesses the ethical and scientific justification for this view and shows it to be unjustified. We critically assess recent statements by professional associations of obstetricians, one that sanctions and one that endorses planned home birth. We base our critical appraisal on the professional responsibility model of obstetric ethics, which is based on the ethical concept of medicine from the Scottish and (...) English Enlightenments of the 18th century. Our critical assessment supports the following conclusions. Because of its significantly increased, preventable perinatal risks, planned home birth in the United States is not clinically or ethically benign. Attending planned home birth, no matter one’s training or experience, is not acting in a professional capacity, because this role preventably results in clinically unnecessary and therefore clinically unacceptable perinatal risk. It is therefore not consistent with the ethical concept of medicine as a profession for any attendant to planned home birth to represent himself or herself as a “professional.” Obstetric healthcare associations should neither sanction nor endorse planned home birth. Instead, these associations should recommend against planned home birth. Obstetric healthcare professionals should respond to expressions of interest in planned home birth by pregnant women by informing them that it incurs significantly increased, preventable perinatal risks, by recommending strongly against planned home birth, and by recommending strongly for planned hospital birth. Obstetric healthcare professionals should routinely provide excellent obstetric care to all women transferred to the hospital from a planned home birth. The professional responsibility model of obstetric ethics requires obstetricians to address and remedy legitimate dissatisfaction with some hospital settings and address patients’ concerns about excessive interventions. Creating a sustained culture of comprehensive safety, which cannot be achieved in planned home birth, informed by compassionate and respectful treatment of pregnant women, should be a primary focus of professional obstetric responsibility. (shrink)

The papers in the 2010 “Clinical Ethics” number of the Journal of Medicine and Philosophy explore issues along La Frontera, the borders and boundaries of clinical ethics. The first three papers in this “Clinical Ethics” number of the Journal explore borders and boundaries drawn within clinical ethics, concerning the moral standing of complementary and alternative medicine, palliative sedation, and induced abortion and feticide. The fourth and fifth papers explore the borders and boundaries between research ethics and clinical ethics.

The paper illustrates how organic chemists dramatically altered their practices in the middle part of the twentieth century through the adoption of analytical instrumentation - such as ultraviolet and infrared absorption spectroscopy and nuclear magnetic resonance spectroscopy - through which the difficult process of structure determination for small molecules became routine. Changes in practice were manifested in two ways: in the use of these instruments in the development of 'rule-based' theories; and in an increased focus on synthesis, at the expense (...) of chemical analysis. These rule-based theories took the form of generalizations relating structure to chemical and physical properties, as measured by instrumentation. This 'Instrumental Revolution' in organic chemistry was two-fold: encompassing an embrace of new tools that provided unprecedented access to structures, and a new way of thinking about molecules and their reactivity in terms of shape and structure. These practices suggest the possibility of a change in the ontological status of chemical structures, brought about by the regular use of instruments. The career of Robert Burns Woodward (1917-1979) provides the central historical examples for the paper. Woodward was an organic chemist at Harvard from 1937 until the time of his death. In 1965, he won the Nobel Prize in Chemistry. (shrink)

It is well-recognized that uncertainty is an endemic feature and limitation of clinical judgment and practice that cannot be eliminated in many cases. Among the tasks of clinical ethics is the responsible management of uncertainties, first articulated in E. Haavi Morreim’s very nice concept of the "moral management of medical uncertainty." The papers in the 2012 Clinical Ethics issue of the Journal provide philosophically innovative and clinically applicable accounts of the varieties of uncertainty in clinical medicine and therefore in clinical (...) ethics: epistemic uncertainty, metaphysical uncertainty, and relational uncertainty. (shrink)

This paper introduces the 2011 number of the Journal on Clinical Ethics. Philosophical critical appraisal is essential for the success of philosophical analysis and argument in clinical ethics. To clear away conceptual underbrush, papers in this Clinical Ethics number of the Journal address genetic engineering, conscience-based objections to forms of health care, placebos, and preventing exploitation of patients to be recruited to become research subjects.

The five papers in the 2008 “Clinical Ethics” number of the journal address the conceptual and empirical foundations of clinical ethics. Three articles take up the concept of professionalism in medicine, exploring its possibilities and implications. The fourth article provides a distinctive, phenomenological account of the “placebo effect,” a vexing topic of surprising durability in the clinical setting. The final article, a systematic review of the qualitative literature on bedside rationing of resources, creates an empirical foundation for philosophical analysis and (...) argument of a distinctive kind. (shrink)

Central concepts and consensus views in clinical ethics are marked by instability. The papers in this number of the Journal take up two such central concepts, quality of life and moral status, and two such consensus views, that germ-line gene transfer should not be undertaken for the purposes of enhancement of human traits and that the ethical obligation of physicians to treat HIV infected patients rests on consent of the physician. One outcome of these philosophical investigations is that these two (...) concepts and consensus views are less stable than one might have thought. I explore the possibility of generalizing this outcome in a reflection on clinical ethics as the management of instability and incompleteness, including the instability and incompleteness of clinical ethics itself. In the course of this reflection I liken clinical ethics to abstract expressionism in mid-twentieth century Western art. (shrink)

In the article, the phenomenon of understanding in mathematics is studied. This topic is relevant in contemporary philosophy of science, in which the classic dichotomy of ‘understanding-explanation‘, characteristic of classical science, undergoes serious transformations. One reason for this transformation is a quantitative increase in the flow of information in modern science. It is clear that in such a situation you want to hold a serious understanding of this information in the context of modern scientific picture of the world. As the (...) modern science is inextricably linked to mathematical science, it is required to rely on the results of studies of the phenomenon of understanding in mathematics. Such studies are already under way in the modern philosophical and scientific literature, although this issue is still relatively new. The author identifies the most important, in his view, types of understanding in math, taking into account the situation of the teaching of mathematics, the situation of mathematical discovery, and ‘mathematical symbolism‘. A study of the main types of understanding in math and the identification of its specificity would have been impossible without the support of the concept of tacit knowledge taken as a methodological tool and author’s previously published works taken as a basis. In this article, the author relies on the classic work on the philosophy of mathematics, as well as the works of famous contemporary Russian and foreign scientists and philosophers. The results of the study are summarized in the form of conclusions. (shrink)