In defense of non-reductionism in the epistemology of testimony

Almost everyone agrees that many testimonial beliefs constitute knowledge. According to non-reductionists, some testimonial beliefs possess positive epistemic status independent of that conferred by perception, memory, and induction. Recently, Jennifer Lackey has provided a counterexample to a popular version of this view. Here I argue that her counterexample fails.     

Delinquency in gangs — Selection or socialization?

Thornberry, Krohn, Lizotte, and Chard-Wierschem's (1993) introduced three models to account for why gangs are associated with high levels of delinquency. Existing research using Thornberry et al.'s (1993) models to explain the gang-delinquency association has been inconclusive. This paper seeks to address this gap in research by incorporating Moffitt's (1993) developmental taxonomy of delinquency within Thornberry et al.'s (1993) explanatory models. A few proposals are put forth in this paper: (1) support for Thornberry et al.'s (1993) models depends on developmental stage of the individual, (2) the selection model explains delinquency of life-course-persistent gang members, while social facilitation model explains delinquency of adolescence-limited gang members, and (3) support for the enhancement model is an artifact of assuming a homogenous gang sample.     

Cornell Realism,Explanation, and Natural Properties

The claim that ordinary ethical discourse is typically true and that ethical facts are typically knowable (ethical conservativism) seems in tension with the claim that ordinary ethical discourse is about features of reality friendly to a scientific worldview (ethical naturalism). Cornell Realism attempts to dispel this tension by claiming that ordinary ethical discourse is, in fact, discourse about the same kinds of things that scientific discourse is about: natural properties. We offer two novel arguments in reply. First, we identify a key assumption that we find unlikely to be true. Second, we identify two features of typical natural properties that ethical properties lack. We conclude that Cornell Realism falls short of dispelling the tension between ethical conservativism and ethical naturalism.     

An application of interactive voice response (ivr) technology to longitudinal studies of daily behavior

A relatively new technology-an interactive voice response (IVR) system-was used to collect selfreport data from 51 male subjects (21–56 years old) concerning daily tobacco and alcohol consumption over a 112-day period. After resolution of initial technical problems, the Touch-Tone data-entry methodology of the IVR was shown to provide notable advantages over traditional longitudinal self-report methodologies. The high compliance rate (93%) for this study was attributed to (1) implementation of important study design characteristics; (2) an innovative compensation scheme that reinforced consistent daily reporting and incorporated feedback to the subjects on a daily basis; (3) a simple, unobtrusive Touch-Tone data-entry interface with the interview and data-collection system that provided subjects with flexibility and time efficiency; and (4) direct coupling of the automated data-collection system and a relational database-management structure, providing immediate access and analysis of collected data.     

Role of L-type Ca2+ channel isoforms in the extinction of conditioned fear

Dihydropyridine (DHP) L-type Ca(2+) channel (LTCC) antagonists, such as nifedipine, have been reported to impair the extinction of conditioned fear without interfering with its acquisition. Identification of the LTCC isoforms mediating this DHP effect is an essential basis to reveal their role as potential drug targets for the treatment of specific anxiety disorders. Ca(V)1.2 and Ca(V)1.3 are the predominant LTCCs in the mammalian brain. However, since no isoform-selective DHP blockers are available, their individual contribution to fear memory extinction is unknown. We used a novel mouse model expressing DHP-insensitive Ca(V)1.2 LTCCs (Ca(V)1.2DHP(-/-) mice) to address this question. In line with previous studies, wild-type (WT) mice treated with systemic nifedipine displayed markedly impaired fear extinction. This DHP effect was completely abolished in Ca(V)1.2DHP(-/-) mice, indicating that it is mediated by Ca(V)1.2, but not by Ca(V)1.3 LTCCs. Supporting this conclusion, Ca(V)1.3-deficient mice (Ca(V)1.3(-/-)) showed extinction identical to the respective WT mice. The inhibition of fear extinction was not observed after intracerebroventricular (i.c.v.) application of different doses of nifedipine, suggesting that this effect is secondary to inhibition of peripheral Ca(V)1.2 channels. The LTCC activator BayK, which lacks neurotoxic effects in Ca(V)1.2DHP(-/-) mice, did not influence the extinction time course. In summary, we demonstrate that LTCC signaling through the Ca(V)1.2 isoform of LTCCs interferes with fear memory extinction, presumably via a peripherally mediated mechanism. Activation of other LTCC isoforms (predominantly Ca(V)1.3) is not sufficient to accelerate extinction of conditioned fear in mice.     

A puzzle about epistemic value and steps towards a solution

Synthese - This paper exposits and makes steps towards solving a puzzle about epistemic value. The puzzle is that several principles about the epistemic value of true beliefs and epistemic disvalue...     

On the edge of language acquisition: inherent constraints on encoding multisyllabic sequences in the neonate brain

To understand language, humans must encode information from rapid, sequential streams of syllables – tracking their order and organizing them into words, phrases, and sentences. We used Near‐Infrared Spectroscopy (NIRS) to determine whether human neonates are born with the capacity to track the positions of syllables in multisyllabic sequences. After familiarization with a six‐syllable sequence, the neonate brain responded to the change (as shown by an increase in oxy‐hemoglobin) when the two edge syllables switched positions but not when two middle syllables switched positions (Experiment 1), indicating that they encoded the syllables at the edges of sequences better than those in the middle. Moreover, when a 25 ms pause was inserted between the middle syllables as a segmentation cue, neonates’ brains were sensitive to the change (Experiment 2), indicating that subtle cues in speech can signal a boundary, with enhanced encoding of the syllables located at the edges of that boundary. These findings suggest that neonates’ brains can encode information from multisyllabic sequences and that this encoding is constrained. Moreover, subtle segmentation cues in a sequence of syllables provide a mechanism with which to accurately encode positional information from longer sequences. Tracking the order of syllables is necessary to understand language and our results suggest that the foundations for this encoding are present at birth.     

Intersection crossing considered as intercepting a moving traffic gap: Effects of task and environmental constraints

Safely crossing an intersection requires that drivers actively control their approach to the intersection with respect to characteristics of the flow of incoming traffic. To further our understanding of the perceptual-motor processes involved in this demanding manoeuvre, we designed a driving simulator experiment in which 13 participants actively negotiated intersections by passing through a gap in the train of incoming traffic. Task constraints were manipulated by varying the size of the traffic gap and the initial conditions with respect to the time of arrival of the traffic gap at the intersection. Environment constraints were manipulated by varying the intersection geometry through changes in the angle formed by the crossroads. The results revealed that the task constraints systematically gave rise to continuous and gradual adjustments in approach velocity, initiated well before arriving at the intersection. These functionally appropriate adjustments allowed the drivers to safely cross the intersection, generally just slightly ahead of the center of the traffic gap. Notwithstanding the fact that the geometry of the intersection did not affect the spatiotemporal constraints of the crossing task, approach behavior varied systematically over geometries, suggesting that drivers rely on the traffic gap's bearing angle. Overall, the pattern of results is indicative of a continuous coupling between perception and action, analogous to that observed in locomotor interception tasks.