Practical Reasoning and the First Person

Philosophia - I argue that while practical reasoning is essentially first personal it does not require having essentially first personal thoughts. I start with an example of good practical...     

Intracerebral source generators characterizing concentrative meditation

Previous researchers have studied meditation practices as a means to understand consciousness as well as altered states of consciousness. Various meditation techniques, such as Transcendental Meditation (TM) and Qigong, have been explored with source localization tools; however, the concentrative meditation technique has yet to be fully studied in this manner. The current study demonstrates findings, which outline differential activation in a self-referential default network during meditation in participants who espouse themselves as regular concentrative meditation practitioners, as well as comparisons with a control group practicing a modified version of the relaxation response. The results are compared with other putative experimental findings employing other meditation techniques, and the findings outlined in the current study are discussed with respect to changes in perceptual awareness often reported by meditators.     

Effects of Numbered Heads Together on the Daily Quiz Scores and On-Task Behavior of Students with Disabilities

Previous research has demonstrated that Numbered Heads Together, a cooperative learning strategy, is more effective than traditional teacher-led instruction in academic areas such as social studies and science. The current study compared the effects of two types of Numbered Heads Together strategies with a baseline condition during 7th grade language arts lessons. Results indicated that three students with various disabilities had higher percent intervals of on-task behavior and daily quiz scores during either Heads Together condition. Teacher satisfaction ratings suggested that Heads Together was easy to implement, and all three students preferred this strategy to baseline instruction. A discussion of study limitations, implications, and future research directions is included.     

Line-bisectioning and obstacle avoidance: Evidence for separate strategies

Previous studies have frequently applied a combination of line-bisection tasks (in which participants indicate the middle of a line) and obstacle avoidance tasks (in which participants move their hand between two obstacles) with the aim of revealing perception–action dissociations in certain neurological disorders, such as visual form agnosia and optic ataxia. However, valid conclusions about the underlying processing pathways can only be drawn if participants apply the same strategy in both tasks (i.e. finding the middle between the obstacles). Yet, this assumption has never been tested directly. In this experiment, we investigated whether participants perform obstacle avoidance and line-bisectioning using similar strategies by manipulating the position of the obstacles and the start position of the hand relative to the obstacles. Our results indicate that the lateral hand position during obstacle avoidance does not only vary as a function of obstacle location but also strongly depends on the start position. Moreover, participants showed increased sensitivity to obstacle shifts occurring closer to the hand's start position. In contrast, during line-bisectioning the sensitivity to obstacles shifts was unaffected by the hand's start position. The findings suggest that during obstacle-avoidance the need to keep a safe distance from the obstacles is balanced with the requirement to minimise energetic demands. In contrast, the main intention during line-bisectioning is to move to the perceived midpoint as accurately as possible. The fact that very different constraints underlie trajectory planning in both tasks implies that caution has to be taken when interpreting differences in performance levels.     

Differential thresholds for limb movement measured using adaptive techniques

Differential thresholds for limb movement were measured in 10 subjects, using the transformed up-down procedure. Subjects were required to indicate which of two random displacement perturbations delivered to their forearms had the larger standard deviation (SD). TheSD of the reference signal was fixed for each experimental condition at one of seven values ranging from 0.05 to 3.2 mm. TheSD of the other signal varied depending on the subject’s response. Using this procedure, the differential threshold for limb movement was calculated to be 8%, which is very similar to the thresholds estimated previously for changes in limb position (9%) and force (7%). The sensitivity of the human proprioceptive system to changes in limb displacement was much greater than anticipated, with subjects being able to resolve a 5-μm difference between two perturbations delivered to their arms.     

Book reviews

Perspectives on Quantum Reality: Non‐Relativistic, Relativistic, and Field‐Theoretic, Rob Clifton, Ed., 1996. Dordrecht, The Netherlands Kluwer Academic Publishers, xi + 243, US$112.00, ISBN 0–7923–3812‐X

Reconstruction of Scientific Theory Change (Russian title: Rekonstrukcija Processa Smeni Fundamentalnih Nauchnih Teorii), Rinat M. Nugayev, 1989. Kazan, Kazan University Press, 208 pp., ISBN: 5–7464–0240–0

The Beat of a Different Drum: The Life and Science of Richard Feynman, Jagdish Mehra, 1994. Oxford: Clarendon Press, pp. xxxii + 630, US$19.95 (Pbk), ISBN 0 19 853948 (Hbk), ISBN 0 19 851887 0 (Pbk)     

UNDERSTANDING,JUSTIFICATION AND THE A PRIORI

Philosophical Studies -