On ‘there is’

Philosophical Studies -     

Measuring the impact of informal caring

A factor-analysis of caregiving impact appraisals amongst a community-derived sample of informal carers of elderly people revealed two negative (care work strain and relationship dissatisfaction) and two positive (care work satisfaction and care lifestyle satisfaction) scales. Validity was assessed by means of concurrent correlations with levels of assistance with daily living tasks provided by carers and levels of behaviour problems exhibited by elderly dependents. Criterion validity was considered in relation to two important carer outcomes; willingness to care and a standardized measure of strain. Each of the four scales was significantly associated with concurrently assessed willingness to care. Care work strain and relationship dissatisfaction were associated with concurrently measured strain symptomology. Evidence of 6-month predictive validity was obtained for the care work strain scale.     

A logic of intentions and beliefs

Intentions are an important concept in Artificial Intelligence and Cognitive Science. We present a formal theory of intentions and beliefs based on Discourse Representation Theory that captures many of their important logical properties. Unlike possible worlds approaches, this theory does not assume that agents are perfect reasoners, and gives a realistic view of their internal architecture; unlike most representational approaches, it has anobjective semantics, and does not rely on anad hoc labeling of the internal states of agents. We describe a minimal logic for intentions and beliefs that is sound and complete relative to our semantics. We discuss several additional axioms, and the constraints on the models that validate them.     

The influence of perceptual and motor factors on bimanual coordination in a polyrhythmic tapping task

Summary In this study the role of perceptual and motor factors on the motor organization (integrated versus parallel) adopted by musically skilled and unskilled subjects in a polyrhythmic tapping task was investigated. Subjects tapped a 3:2 polyrhythm to match the timing of two isochronous tone trains, one tone train for each hand. Perceptual factors were examined by the manipulation of the frequency difference between the tone trains to produce either an integrated or a streamed percept. Motor factors were examined by comparison of performance on two versions of the 3:2 polyrhythm. In one (simultaneous) version, each cycle of the polyrhythm began with a simultaneous left- and right-hand tap. In the other (shifted) version a 100-ms interval was introduced between the initial left and right taps in each cycle. Examination of the pattern of variances and covariances among intertap intervals suggested that most of the subjects in this study adopted an integrated motor organization that involved interleaving the timing of the two hands. Further analysis revealed that a serial chained model described the pattern of covariances best for the simultaneous pattern, whereas a hierarchical organization described the pattern of covariances for the shifted pattern best. The finding that performance was more accurate with integrated tones than with streamed tones provides some support for a perceptual-motor facilitation hypothesis.     

Grading the ‘cultural literacy’ project

The essay examines the argument advanced by E.D. Hirsch, Jr., for instituting ‘cultural literacy’ as a fundamental priority of schools. A number of confusions and equivocations in Hirsch's reasoning are identified, and the propensity of his project to indoctrinate is exposed. Among the features of Hirsch's argument shown to be troubling are his shifting construal of ‘language’, his inconsistency about the requirements of cultural literacy, and his uncritical relation to traditional images of the American past and present. The upshot is to raise the question why Hirsch's project has elicited wide support and praise.     

The role of compliance in hypnotic and nonhypnotic analgesia

We modified the standard procedure for administering finger pressure pain in order to assess the extent to which subjects biased their reports of pain reduction when exposed to compliance-inducing instructions. Experiment 1 used only highly hypnotizable subjects and found that compliance-induced reductions in reported pain were about half as large as the reported reductions produced by hypnotic analgesia suggestions. Experiment 2 used low as well as high hypnotizables and administered hypnotic or nonhypnotic analgesia instructions and compliance instructions to the same subjects on separate pain trials. Reported pain reductions produced by hypnotic and nonhypnotic analgesia suggestions and those produced by compliance instructions were substantially and significantly correlated. Furthermore, hypnotizability correlated with compliance-induced reported pain reductions as highly as it correlated with the reported reductions produced by hypnotic analgesia suggestions. Among high hypnotizables (but not low hypnotizables) compliant responding was predicted by social desirability. The findings of both studies indicate that compliance strongly influences the reports of hypnotic and nonhypnotic analgesia proffered by high hypnotizables. The role of compliance in the pain reductions reported by low hypnotizables is less clear-cut.     

On the distinction between artifacts and information

Sperling, Landy, Dosher, and Perkins (1989) argued that all previous research on the kinetic depth effect has been contaminated by stimulus artifacts, and they developed a new task that they believe can successfully overcome this problem. The present discussion offers a counter-argument that artifacts are not as pervasive in previous research as Sperling et al. imply and that their proposed method is subject to precisely the same limitations as earlier studies. Also discussed are some general guidelines of experimental design in this type of research to minimize the possibility that subjects will adopt an inappropriate response strategy that does not truly reflect their visual perceptions of three-dimensional form.     

Visual perception of smoothly curved surfaces from double-projected contour patterns

This research was designed to examine how human observers are able to perceive the 3-dimensional structure of smoothly curved surfaces from projected patterns of surface contours. Displays were generated by using a method of double projection that made it possible to cover a surface with a wide range of contour patterns of varying geometric structure and to eliminate systematic variations of image shading. The compelling impression of 3-dimensional form from these patterns provides strong evidence that the ability of observers to perceptually interpret surface contours is considerably less restrictive than would be reasonable to expect on the basis of existing computational models. Results suggest that the perceptual analysis of surface contours is able to exploit statistical regularities of contour structure over appropriately large regions of visual space.