Recovery of 3-D shape from deforming contours

Three experiments were conducted to examine the accuracy of 3-D shape recovery from deforming-contour displays. The displays simulated silhouettes of ellipsoids rotating about a vertical axis. Subjects judged the horizontal cross-section of the ellipsoids. The shape of the ellipsoid, the position of the axis of rotation, and the type of projection were manipulated in Experiment 1. The results indicated relatively accurate shape recovery when the major axis of the ellipsoid was small. In Experiment 2, the shape of the ellipsoid and the velocity and curvature of the contour were manipulated. When the rate of deformation of curvature was decreased, more eccentric shapes were reported. In Experiment 3, the shape of the object and the amount of simulated rotation were manipulated. Subjects made both shape and extent of rotation judgments. The results showed that eccentricity of shape responses could be accurately predicted from rotation responses, suggesting that the recovery of 3-D shape from smooth, deforming contours is dependent on the perceived extent of rotation.     

Formant frequency characteristics of children, young adult, and aged female speakers

Previous literature indicates that a difference may exist between formant frequencies (F1 and F2) of children, young adult, and elderly speakers. The purpose of this study was to compare F1 and F2 of 3 young, 6 young adult, and 3 elderly female speakers for the /i/, /ae/, /u/, and /a/ vowels. Analysis indicates a trend towards vowel reduction across the life span. These findings support previous research regarding age-associated acoustic changes as well as support for the possible anatomical and physiological alterations which may influence such changes.     

The effect of training on visual alignment discrimination and grating resolution.

The effect of training on an observer's ability to detect the misalignment of three points, a hyperacuity, and to resolve a six-line grating was studied in a transfer-of-training design with observers (4 in each of two experiments) who were experienced in making psychophysical judgments of other visual stimuli. The transfer-of-training design enabled us to look for any training-based improvement. Long periods of training produced no statistically significant improvement in performance under any condition. There were small practice-based improvements, but the primary patterns indicated threshold fluctuation rather than improvement. We interpret the results to indicate that the neural mechanisms underlying three-point alignment and grating discrimination, like those for gap bisection (Klein & Levi, 1985), are not malleable to any significant extent.     

Development and evaluation of CHIPASAT, an attention test for children: II. Test-retest reliability and practice effect for a normal sample.

The CHIPASAT (Children's Paced Auditory Serial Addition Task), developed to assess auditory-verbal attention, was administered to a sample of 70 normal school children on two occasions separated by an interval of approximately 4 weeks. A significant practice effect was found, independent of age and sex, with performance improved by approximately 20% on retest. The test-retest reliability of .90 was significant, indicating task stability. The practice effect was consistent with that reported in the literature for the adult PASAT, and reasons for this effect are discussed. Initial test raw scores on WISC--R Arithmetic and Digit Span subtests yielded low but significant correlations of .38 and .35 with CHIPASAT scores.     

The Fraser illusion: complex figures

The cause of the Fraser illusion, which occurs when a line made up of tilted segments itself appears tilted, is examined further. In this series of experiments, we used figures that resembled the original Fraser illusion; they were more complex than those reported on in our previous paper (Stuart & Day, 1988). The figures were used to explore two theories of the Fraser illusion further: that it is the result of interactions between orientation selective units, and that it is a consequence of the local, distributed processing of orientation. The presence of background elements like those used in the original illusion led to an increase in the strength of the illusion, but the shape of these elements had no differential effect on illusion strength. There was a differential effect of the background on the assimilative and contrast illusions, owing respectively to small and large tilts of the inducing elements. The illusion was markedly reduced at small visual angles when the background was absent, but it was only slightly affected when the background was present. All these findings are difficult to explain in terms of interactions between single units, either at the same or at different scales in the image. The effects of luminance contrast and isoluminance on the illusion were not consistent with either theory, but they indicated that researchers need to consider the role of figure-ground organization in this illusion.     

Effects of media violence on viewers' aggression in unconstrained social interaction

This article provides a meta-analytic review of the experimental effects of media violence on viewers' aggression in unstructured social interaction. In the reviewed experiments, children or adolescents were exposed to violent or control presentations and their postexposure behavior was coded for aggression during spontaneous social interaction. Exposure to media violence significantly enhanced viewers' aggressive behavior when the findings were aggregated across studies, but the effect was not uniform across investigations. Only suggestive evidence was obtained concerning moderators of the effect: Marginally stronger relations were obtained in those studies using a cross-section of the normal population of children (vs. emotionally disturbed children) and in those studies conducted in laboratory settings (vs. other contexts).     

Autonomic determinism: the modes of autonomic control, the doctrine of autonomic space, and the laws of autonomic constraint.

Contemporary findings reveal that the multiple modes of autonomic control do not lie along a single continuum extending from parasympathetic to sympathetic dominance but rather distribute within a 2-dimensional space. The physiological origins and empirical documentation for the multiple modes of autonomic control are considered. Then a formal 2-dimensional conception of autonomic space is proposed, and a quantitative model for its translation into a functional output surface is derived. It is shown that this model (a) accounts for much of the error variance that has traditionally plagued psychophysiological studies, (b) subsumes psychophysiological principles such as the law of initial values, (c) gives rise to formal laws of autonomic constraint, and (d) has fundamental implications for the direction and interpretation of a wide array of psychophysiological studies.     

Spacing judgments as an index of integration from context-induced relational processing: Implications for the free recall of ambiguous prose passages

The effect of information integration on the recall of ambiguous prose passages was investigated. In Experiment 1, subjects read ambiguous passages that were difficult to comprehend without titles. In judging the relative positions in the passages of pairs of test sentences, subjects performed better when they read passages headed by a suitable title than when they read untitled passages or received a title at the time of testing. In Experiment 2, subjects provided with a title at encoding also better discriminated complete old sentences from foils composed of fragments of two different old sentences than did subjects provided with no titles or with titles at the time of testing. These two tests index the degree of inter- and intrasentence information integration, respectively. Two findings indicated that integration affected free recall of an ambiguous passage. First, when the degree of integration of the passage's propositions was controlled, free recall of the passage was no different for subjects who did or did not know the passage's title at encoding. Second, inducing subjects to comprehend the passage's sentences individually, without relating them to one another, reduced free recall of the passage.     

Somatic complaints in anxious children

Although stomachaches and headaches are considered characteristic of children with anxiety disorders, there is converging evidence that a broader range of somatic symptoms may be associated with children's expressions of anxiety. The purpose of this study was to determine the prevalence of somatic complaints in anxious children. The results indicated that children with anxiety disorders endorsed the presence of many different somatic complaints, and that contrary to clinical intuition, stomaches and headaches were not among the most commonly reported symptoms. In addition, the anxious children endorsed significantly more somatic complaints when compared to normal controls. Furthermore, the symptom pattern reported by anxious children indicated the presence of both the somatic and cognitive components usually associated with panic attacks, although none of the children met diagnostic criteria for panic disorder. The results are discussed in terms of the contribution of somatic symptoms to the understanding of anxiety disorders in children.     

Selective impairment of thematic role assignment in sentence processing

We report the performance of a brain-damaged subject showing a particularly pure dissociation between impairment in processing thematic roles and spared ability to process the morphological structure of sentences. The thematic role processing impairment was observed in both comprehension and production of active and passive reversible sentences, although it was more severe for the latter sentence type. This pattern of performance poses interesting challenges for current conceptions of the nature of language breakdown in aphasia and for models of normal sentence processing.