A human-centered approach for designing World-Wide Web browsers

Because the World-Wide Web has features that are not found in traditional information systems, it has some unique problems pertaining to human use, such as the difficulty of searching for specific information. This paper describes human cognitive limitations pertinent to the design of Web browsers and provides a conceptual model for human information processing on the Web. It also compares user strategies and use of browser functions for two tasks that differ in the specificity of the information that is to be retrieved. General principles and specific recommendations for the design of Web browsers are derived from these considerations.     

The perception of shape and curvedness from binocular stereopsis and structure from motion

The integration of binocular stereopsis and kinetic depth was measured for two distinct aspects of 3-Dstructure: (1)shape index, which is a measure of scale-independent structure, and (2)curvedness, which is a measure of scale-dependent structure. We found that motion contributes significantly more to judged shape index than it does to judged curvedness, and stereo contributes significantly more to judged curvedness than it does to judged shape index. This suggests that the differences in the relative contribution of motion and stereo reported here occurred because these two sources do not equally specify the scale-dependent and scale-independent aspects of surface structure. Furthermore, these results seem to be inconsistent with integration models in which the different visual cues all initially contribute to the same single representation of 3-Dstructure.     

Heading and path information from retinal flow in naturalistic environments

In four experiments, we explored the heading and path information available to observers as we simulated their locomotion through a cluttered environment while they fixated an object off to the side. Previously, we presented a theory about the information available and used in such situations. For such a theory to be valid, one must be sure of eye position, but we had been unable to monitor gaze systematically; in Experiment 1, we monitored eye position and found performance best when observers fixated the designated object at the center of the display. In Experiment 2, when we masked portions of the display, we found that performance generally matched the amount of display visible when scaled to retinal sensitivity. In Experiments 3 and 4, we then explored the metric of information about heading (nominal vs. absolute) available and found good nominal information but increasingly poor and biased absolute information as observers looked farther from the aimpoint. Part of the cause for this appears to be that some observers perceive that they have traversed a curved path even when taking a linear one. In all cases, we compared our results with those in the literature.     

Tic douloureux, Parkinson’s disease and the herpes connection

Several cases encountered in psychiatric practice are described in which herpetic involvement of the trigeminal nerve appeared to be crucial to the pathophysiology of the patients’s illness. A brief history of herpes is discussed in terms of the anatomy and physiology of the trigeminal nerve. Particular attention is given to the effects of intraneuronal herpes on gasserian ganglion and spinal nuclei discharge threshoolds, as well as viral pathways directly impacting the substantia nigra. Evidence characterizing Parkinson’s disease as one of several important manifestations of CNS herpes is covered. This article will be presented, by invitation, at the Neuroscience Seminar, Department of Medicine, University of Otago, Dunedin, New Zealand, on 19 August 1997.     

Set- and Element-Level Stimulus-Response Compatibility Effects for Different Manual Response Sets

In a previous study of two-choice reactions, pairings of spatial stimuli with bimanual presses made on a keyboard and verbal stimuli with unimanual aimed movements made on a display screen showed higher set-level compatibility than the opposite pairings; element-level compatibility (i.e., mapping) effects were also larger for the conditions with high set-level compatibility than for those whose set-level compatibility was low. In the 4 experiments described here, the relevant factors were isolated, allowing the determinants of those compatibility differences to be evaluated in more detail. Forty-eight students participated in Experiment 1, and 24 each in Experiments 2, 3, and 4. The primary determinant of the set-level compatibility variation was whether the response alternatives involved 1 or 2 effectors, but the differences in element-level compatibility effects were determined primarily by the distinction between responding on the screen as opposed to on the keyboard. Implications for models of stimulus-response compatibility are examined.     

Multiple Goals and Tactical Behaviors in Social Conflicts1

The hypotheses of a multiple goals theory of conflict were supported in a study in which 264 American students reported on a conflict that they had experienced. The results showed that 95% of subjects had more than 1 goal during the conflict; social goals were more strongly activated than resource goals; subjects' tactical behavior was determined by the social goals; and effects of personal and situational variables on tactical choice were mediated by activated goals. Factor analyses identified 6 goals and 4 types of tactics.     

Religious Coping and Heart Transplantation: From Threat to Health

Previous research has established the existence of homogeneous religious coping profiles in cardiac-transplantation candidates labeled as the deferring/collaborators, self-directors, and the eclectic religious copers. However, their prospective impact on outcome has not yet been established. This paper examines potential differences between pre-cardiac transplantation religious coping cluster groups on post-cardiac transplantation quality of life (physical functioning, mental health, and general health). Results indicated that the religious coping profiles of deferring/collaborators and self-directors had significantly better scores on mental health and general health than did the eclectics. Implications for religious-coping research and clinical practice are discussed.     

Perfectionism and Suicide Ideation in Adolescent Psychiatric Patients

This study was conducted to examine the relations between dimensions of perfectionism and suicide ideation in an adolescent psychiatric sample. A sample of 66 adolescents from an inpatient psychiatric facility completed the Child and Adolescent Perfectionism Scale, the Child's Hopelessness Scale, and the Suicide Ideation Questionnaire. Overall, the results indicated that socially prescribed perfectionism was associated with greater suicide ideation and that it, along with hopelessness, accounted for unique variance in suicide ideation scores. The findings are discussed in terms of their practical and theoretical significance as well as their consistency with similar research with adults.     

Conscience and conscientious actions in the context of MCOs

Managed care organizations can produce conflicts of obligation and conflicts of interest that may lead to problems of conscience for health care professionals. This paper provides a basis for understanding the notions of conscience and conscientious objection and offers a framework for clinicians to stake out positions grounded in personal conscience as a way for them to respond to unacceptable pressures from managers to limit services.     

Book reviews

Socializing Epistemology: The Social Dimensions of Knowledge, Frederick F. Schmitt, Ed., 1994. Lanham, MD, Rowman and Littlefield, ix + 315 pp., US$22.95, ISBN: 0847679594

A Dynamic Systems Approach to the Development of Cognition and Action, Esther Thelen & Linda B. Smith. Cambridge, MA, MIT Press, xxii + 376 pp., $50, ISBN 0–262–20095–3 cloth

From Kant to Hilbert: A Source Book in the Foundations of Mathematics, William B. Ewald, Ed., 1996. Oxford, Oxford University Press. xviii+ 1340 pp., £195.00, two volumes, ISBN 0–19–853271–7 (the set)