Gradual growth versus shape invariance in perceptual decision making

A dominant theme in modeling human perceptual judgments is that sensory neural activity is summed or integrated until a critical bound is reached. Such models predict that, in general, the shape of response time distributions change across conditions, although in practice, this shape change may be subtle. An alternative view is that response time distributions are shape invariant across conditions or groups. Shape invariance is predicted by some race models in which the first of several parallel fibers to communicate the signal determines the response. We competitively assess a specific gradual growth model, the one-bound diffusion model, against a natural shape-invariant competitor: shape invariance in an inverse Gaussian distribution. Assessment of subtle shape change versus shape invariance of response time distributions is aided by a Bayesian approach that allows the pooling of information across multiple participants. We find, conditional on reasonable distributional assumptions, subtle shape changes in response time that are highly concordant with a simple diffusion gradual growth model and discordant with shape invariance.     

Ambiguity aversion: the explanatory power of indeterminate probabilities

Daniel Ellsberg presented in Ellsberg (The Quarterly Journal of Economics 75:643–669, 1961) various examples questioning the thesis that decision making under uncertainty can be reduced to decision making under risk. These examples constitute one of the main challenges to the received view on the foundations of decision theory offered by Leonard Savage in Savage (1972). Craig Fox and Amos Tversky have, nevertheless, offered an indirect defense of Savage. They provided in Fox and Tversky (1995) an explanation of Ellsberg’s two-color problem in terms of a psychological effect: ambiguity aversion. The ‘comparative ignorance’ hypothesis articulates how this effect works and explains why it is important to an understanding of the typical pattern of responses associated with Ellsberg’s two-color problem. In the first part of this article we challenge Fox and Tversky’s explanation. We present first an experiment that extends Ellsberg’s two-color problem where certain predictions of the comparative ignorance hypothesis are not confirmed. In addition the hypothesis seems unable to explain how the subjects resolve trade-offs between security and expected pay-off when vagueness is present. Ellsberg offered an explanation of the typical behavior elicited by his examples in terms of these trade-offs and in section three we offer a model of Ellsberg’s trade-offs. The model takes seriously the role of imprecise probabilities in explaining Ellsberg’s phenomenon. The so-called three-color problem was also considered in Fox and Tversky (1995). We argue that Fox and Tversky’s analysis of this case breaks a symmetry with their analysis of the two-color problem. We propose a unified treatment of both problems and we present a experiment that confirms our hypothesis.     

The Moral Laboratory: On Kant’s Notion of Pedagogy as a Science

Following Kant, it is clear that, but probably not completely how we are morally obligated. I will point out that there are three possible ways to struggle for an understanding of how we can be obligated as rational beings and also as ordinary human beings. There is (a) the argument from rational feeling (‘Achtung’), (b) the argument from language, and finally (c) the argument from systematization. Reading the later passages of the ‘Critique of pure Reason’ and following its instructions, we will understand why education has to be founded by the same kind of argumentation as the natural sciences. The systematical analysis of Kant’s analogy between the physical body and the moral obligation will explain the suspected gap between our just rational and our whole selves. The most important part of the demanded bridge will be Kant’s Moral Laboratory.     

Is expanding retrieval a superior method for learning text materials?

Expanding retrieval practice refers to the idea that gradually increasing the spacing interval between repeated tests ought to promote optimal long-term retention. Belief in the superiority of this technique is widespread, but empirical support is scarce. In addition, virtually all research on expanding retrieval has examined the learning of word pairs in paired-associate tasks. We report two experiments in which we examined the learning of text materials with expanding and equally spaced retrieval practice schedules. Subjects studied brief texts and recalled them in an initial learning phase. We manipulated the spacing of the repeated recall tests and examined final recall 1 week later. Overall we found that (1) repeated testing enhanced retention more than did taking a single test, (2) testing with feedback (restudying the passages) produced better retention than testing without feedback, but most importantly (3) there were no differences between expanding and equally spaced schedules of retrieval practice. Repeated retrieval enhanced long-term retention, but how the repeated tests were spaced did not matter.     

Expanding the study of U.S. religion: Reflections on the state of a subfield

The study of U.S. religion, which dates from the 19th century, expanded its sources, methods, and scope during the last quarter of the 20th century, as specialists offered more inclusive historical narratives. That methodological expansion never went far enough, however, and the impulse toward narrative inclusiveness has been restrained in recent years. The subfield, I argue, now faces a number of challenges that also confront other specializations in the study of religion—contraction, overspecialization, fragmentation, and parochialism. After a focused overview of the subfield’s history, I discuss those challenges. Proposing a tentative response, I suggest that specialists celebrate methodological diversity and theoretical sophistication, encourage comparative and translocative studies, and increase collaboration across disciplinary boundaries and national borders. Finally, I suggest that we expand the subfield’s temporal span and geographical scope and reframe the study of U.S. religion in terms of the Atlantic World, the Pacific World, and the Western Hemisphere.     

The change-of-standard effect: Distorted standards and adjusted impressions

Previous accounts of the memory distortion known as the change-of-standard effect hypothesize that participants form a relative impression of a target at encoding and later use that impression with the average of all items to recall the target (Higgins & Lurie, 1983). In three experiments, we investigated the standard and the integration of the standard with the relative impression. Experiments 1 and 2 show that participants’ subjective average at recall is distorted toward recent stimuli: It is computed when required and is therefore affected by the items’ accessibility at that time. Furthermore, the impression’s influence on recall is relatively small when the context changes between encoding and decoding. Experiment 3 shows that this change in the impression’s influence occurs only when the participant integrates information across sessions, suggesting that such tasks make participants aware of the changed context and cause them to adjust the use of their impression in recalling the target.     

Concept Grounding and Knowledge of Set Theory

C. S. Jenkins has recently proposed an account of arithmetical knowledge designed to be realist, empiricist, and apriorist: realist in that what’s the case in arithmetic doesn’t rely on us being any particular way; empiricist in that arithmetic knowledge crucially depends on the senses; and apriorist in that it accommodates the time-honored judgment that there is something special about arithmetical knowledge, something we have historically labeled with ‘a priori’. I’m here concerned with the prospects for extending Jenkins’s account beyond arithmetic—in particular, to set theory. After setting out the central elements of Jenkins’s account and entertaining challenges to extending it to set theory, I conclude that a satisfactory such extension is unlikely.     

Demea’s Dilemmas

This paper considers how Descartes's and Hume's sceptical challenges were appropriated by Christian Wolff and Johann Nicolaus Tetens specifically in the context of projects related to Kant's in the transcendental deduction. Wolff introduces Descartes's dream hypothesis as an obstacle to his account of the truth of propositions, or logical truth, which he identifies with the 'possibility' of empirical concepts. Tetens explicitly takes Hume's account of our idea of causality to be a challenge to the `reality' of transcendent concepts in general, a challenge he addresses by locating the source of this concept in the understanding rather than in the imagination. After considering this background, I turn to Kant's deployment of apparently traditional sceptical concerns at the outset of the transcendental deduction and argue that he does not there intend to introduce a global sceptical challenge and, accordingly, that there are historical grounds for doubting that the transcendental deduction is intended as an anti-sceptical argument.     

Antoine Le Grand on the identity over time of the human body

ABSTRACT

This paper studies Antoine Le Grand's account of organic identity over time in human bodies. In response to Aristotelian critics who argued that the Cartesian rejection of the Aristotelian ontology of matter and form had put in jeopardy the diachronic identity of material substances in general and of living bodies in particular, Le Grand argued that the identity over time of the human body could be accounted for without the traditional notions of matter and form. The paper shows how he drew on both the Cartesian metaphysics of mind and body and contemporary views on human anatomy and organic generation to develop a unique account of bodily identity over time in human animals.