Representationalism is a dead end

Synthese - Representationalism—the view that scientific modeling is best understood in representational terms—is the received view in contemporary philosophy of science. Contributions...     

Processing of new arguments at clause boundaries

In a subject-paced reading-time study, we examined the processing of new arguments at clause boundaries. Word reading times increased with the cumulative number of new-argument nouns at clause boundaries (as well as at sentence boundaries). New-argument nouns had a greater impact at clause boundaries than at nonboundary locations. In accordance with a buffer-integrate-purge model of reading (see Jarvella, 1979), the increase of reading times at boundaries was attributed to the integration of new information from the current sentence with prior information in the text representation. The increase at nonboundary locations was attributed to the growing load of buffering the new information. Reading times at clause boundaries were influenced to a greater extent by text-level integration than by such sentence-level processes as organization of words into clauses and linking of clauses within a sentence. The new contribution of this study was that it showed that clause boundaries provide an opportunity not only for sentence-level processes, but also for a text-level process, namely, the integration of text-new information with the growing text representation.     

Impairment of nonlinguistic hand movements in a deaf aphasic

A deaf man who became aphasic for sign language was seen 4 years after a left-hemisphere stroke. While not impaired on traditional apraxia tests, he was impaired, relative to nonaphasic deaf controls, in the imitation of complex nonlinguistic hand movements. He was not impaired on single isolated movements. These findings are interpreted as supporting a concept of left-hemisphere function which emphasizes complex motor control.     

Conditioned taste aversion is enhanced when the unconditioned stimulus is presented in a different context

Using a conditioned taste aversion procedure with rats as the subjects, two experiments examined the effect of presenting a conditioned stimulus (CS saccharin solution) in one context followed by an unconditioned stimulus (US LiCl) in a different context. Experiment 1 showed that animals which received the above-mentioned procedure (Group D) showed a more marked conditioned aversion to the CS than animals which were given both the CS and the US in the same context (Group S). Experiment 2 found that in both Group D and Group S, aversion to the CS increased when the subjects were exposed to the conditioned context after the conditioning. These findings supported the argument that the strength of the CS-US association acquired during conditioning is compared with that of the context-US to determine the magnitude of aversion revealed to the CS.     

Perception of nonlinguistic auditory rhythms by the speech hemisphere

Two groups of right-handed young adults were tested on a series of handedness measures and on dichotic nonverbal rhythmic sequences. Cross-validated multiple regression analysis revealed that all of the cerebral-lateralization/manual-praxis measures were positively related to the degree of left-hemisphere perceptual asymmetry for nonverbal rhythms (Crawford peg, scissor, handwriting, Crawford screws, tracing, total R = .67). Seventeen of the 52 subjects manifested significant (p < .05) left-hemisphere laterality coefficients for the dichotic stimuli. More complex rhythms elicited greater left-hemisphere perceptual preference. The results are discussed in reference to the concept of cerebral lateralization.     

Detection of stimulus motion in 5-month-old infants

Five-month-old infants were tested by the method of preferential looking for discrimination between a pattern undergoing oscillating apparent motion and an identical static pattern. Sensitivity to small spatial displacements was evident at temporal frequencies of 8 and 16 Hz. Preference for the moving display was related independently to the temporal frequency of oscillation and the magnitude of the spatial displacement. Preferences for the moving display increased asymptotically across spatial displacements from 11 to 89 arc min. Preferences peaked between temporal oscillation frequencies of 8 and 16 Hz. Preference was not related to the ratio of these two variables--velocity. The minimum displacement threshold of 7.36 arc min was found to depend on the size of the elements in the pattern and on the temporal frequency of oscillation. The results demonstrate that motion-sensitive mechanisms responsive to small spatial displacements are present at 5 months of age.     

Circular vection is independent of stimulus eccentricity

The sensation of self-rotation induced by viewing a surround rotating about the observer's vertical axis (circular vection or CV) was investigated with equal-area stimuli located in either the central, the mid-peripheral, or the far-peripheral visual field. Magnitude estimation responses indicated greater CV with larger stimulus area, but no significant differences in CV sensations as a function of stimulus eccentricity. This pattern of results does not support the belief that CV is dominated by peripheral stimulation when equal-area stimuli are compared.     

Reconstructing the professional at the end of modernity

Faced with incidents of sexual misconduct within the professional ministry, some would have us return to a construct of the professional from the past and some would reject the construct altogether. Both those approaches may perpetuate systemic factors that contribute to injustice. This article explores the history of the professional construct and its challenges, and offers a reconstruction that could support a more just relationship between ministers and members of congregations.     

The effect of a masked stimulus on the response to the masking stimulus

Four experiments are reported in which the subjects had to respond to a target that masked a preceding prime via metacontrast masking. In one part of Experiment l, the subjects discriminated the target's shape (square or diamond) by a motor-choice reaction, and in another part they had to respond with a simple reaction. The prime was neutral (circular) with respect to the target's shape. The data showed a facilitation effect. In both tasks the reaction time was reduced by the masked prime. However, the reduction was more pronounced with simple reaction than with choice reaction. In the other experiments, additional primes were used with the same angular shapes as the targets. In Experiments 2 and 3, after discriminating the target's shape by a choice reaction, the subjects had to judge the prime's shape in a signal-detection task. While neither the d' value for discriminating the angular primes from the circular ones (Exp. 2) nor the d' value for distinguishing between the angular primes (Exp. 3) was different from zero, the choice-reaction data showed a congruency effect. With a congruent prime (i.e., a prime that had the same shape as the target), the reaction times were reduced. With an incongruent prime, the reaction times grew. In Experiment 4 the errors were investigated. The facilitation effect was present in the RT, but not in the number of errors, whereas the congruency effect was present in the number, but not in the RT of errors.While the facilitation effect can be attributed either to an unspecific activation by the masked prime or to an influence of the prime on attentional processes, the congruency effect can be explained by the assumption that the masked prime directly activates the specific response, which corresponds to the prime's shape.     

Sedation and care at the end of life

This special issue of Theoretical Medicine and Bioethics takes up the question of palliative sedation as a source of potential concern or controversy among Christian clinicians and thinkers. Christianity affirms a duty to relieve unnecessary suffering yet also proscribes euthanasia. Accordingly, the question arises as to whether it is ever morally permissible to render dying patients unconscious in order to relieve their suffering. If so, under what conditions? Is this practice genuinely morally distinguishable from euthanasia? Can one ever aim directly at making a dying person unconscious, or is it only permissible to tolerate unconsciousness as an unintended side effect of treating specific symptoms? What role does the rule of double effect play in making such decisions? Does spiritual or psychological suffering ever justify sedation to unconsciousness? What are the theological and spiritual aspects of such care? This introduction describes how the authors in this special issue wrestle with such questions and shows how each essay relates to the author’s individual position on palliative sedation, as developed in greater detail within his contribution.     

Reaction time to a second stimulus as a function of intensity of the first stimulus

Reaction time (RT) to the second of two stimuli presented in rapid succession was examined as a function of the intensity of the first stimulus (S₁). It was found that the delay in RT₂ was greater following a dim first stimulus than following a bright first stimulus. The magnitude of this increase corresponded to the difference in RTs to the two intensity levels of S₁. These results support the prediction of a single channel model of response selection. Examination of mean first RTs revealed a general elevation in latency of RT. However, since this increase was not influenced by the inter-stimulus interval (ISI) or by the intensity of the second stimulus (S₂), and since the same increase was found on “catch trials“ where no S₂ was presented, this increase is considered to be a function of change in set in the double response situation.     

Shoulder joint position sense is not enhanced at end range in an unconstrained task

Shoulder joint position sense (JPS) is important for maintaining stability and contributing to coordinated movements. It is provided by afferent and centrally-derived signals interpreted and integrated by the central nervous system (CNS) for subsequent use. Shoulder JPS is enhanced as the joint approaches end range of motion (ROM) in studies involving internal and external rotation with the arm supported, but this finding has not been confirmed in unconstrained movements. To address this issue, the present study examined the effect of shoulder position in the horizontal plane on JPS at a constant elevation. Twenty-three healthy individuals were recruited from a university campus. Subjects attempted to actively replicate various target positions in both plane and elevation. Target positions consisted of five positions in the horizontal plane, normalized to individual horizontal abduction ROM, at 90° of arm elevation. All target positions were tested three times, and average absolute and variable errors were analyzed for each position. No differences in either absolute (p = .312) or variable (p = .185) errors were observed between positions. These results further support the contention that the muscle spindles are a dominant source of afferent feedback regarding shoulder JPS in unconstrained movements, even approaching end ROM, when the capsuloligamentous receptors are active.     

Running is the neurogenic and neurotrophic stimulus in environmental enrichment

Environmental enrichment (EE) increases dentate gyrus (DG) neurogenesis and brain-derived neurotrophic factor (BDNF) levels. However, running is considered an element of EE. To dissociate effects of physical activity and enrichment on hippocampal neurogenesis and BDNF levels, young female C57Bl/6 mice were housed under control, running, enrichment, or enrichment plus running conditions, and injected with bromodeoxyuridine. Cell genesis was assessed after 12 d and differentiation was analyzed 1 mo later. In addition, locomotor activity in the open field and hippocampal mature BDNF peptide levels were measured. Open-field adaptation was improved in all groups, compared to controls, but more so with running. New cell proliferation, survival, neuron number, and neurotrophin levels were enhanced only when running was accessible. We conclude that exercise is the critical factor mediating increased BDNF levels and adult hippocampal neurogenesis.