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Biomedical subjects

John M Kennedy

Publications and source records attributed to John M Kennedy.

15 recordsLinked to original sources
PubMed2006

Looking at perspective pictures from too far, too close, and just right.

A central problem for psychology is vision's reaction to perspective. In the present studies, observers looked at perspective pictures projected by square tiles on a ground plane. They judged the tile dimensions while positioned at the correct distance, farther or nearer. In some pictures, many tiles appeared too short to be squares, many too long, and many just right. The judgments were strongly affected by viewing from the wrong distance, eye height, and object orientation. The authors propose a 2-factor angles and ratios together (ART) theory, with the following factors: the ratio of the visual angles of the tile's sides and the angle between (a) the direction to the tile from the observer and (b) the perpendicular, from the picture plane to the observer, that passes through the central vanishing point.

Adolescent↗
PubMed2006

Foreshortening, convergence and drawings from a blind adult.

Esref is a congenitally totally blind man, practiced in drawing. He was asked to draw solid and wire cubes situated in several places around his vantage point. He used foreshortening of receding sides and convergence of obliques, in approximate one-point perspective. We note that haptics provides information about the direction of objects--the basis of perspective.

Blindness↗
PubMed2006

Viewpoint and orientation influence picture recognition in the blind.

In the first three experiments, subjects felt solid geometrical forms and matched raised-line pictures to the objects. Performance was best in experiment 1 for top views, with shorter response latencies than for side views, front views, or 3-D views with foreshortening. In a second experiment with blind participants, matching accuracy was not significantly affected by prior visual experience, but speed advantages were found for top views, with 3-D views also yielding better matching accuracy than side views. There were no performance advantages for pictures of objects with a constant cross section in the vertical axis. The early-blind participants had lower performance for side and frontal views. The objects were rotated to oblique orientations in experiment 3. Early-blind subjects performed worse than the other subjects given object rotation. Visual experience with pictures of objects at many angles could facilitate identification at oblique orientations. In experiment 5 with blindfolded sighted subjects, tangible pictures were used as targets and as choices. The results yielded superior overall performance for 3-D views (mean, M = 74% correct) and much lower matching accuracy for top views as targets (M = 58% correct). Performance was highest when the target and matching viewpoint were identical, but 3-D views (M = 96% correct) were still far better than top views. The accuracy advantage of the top views also disappeared when more complex objects were tested in experiment 6. Alternative theoretical implications of the results are discussed.

Adult↗
PubMed2006

Similes on the Internet have explanations.

We searched the Internet for expressions linking topics, such as crime, and vehicles, such as disease, as similes (crime is like a disease) and as metaphors (crime is a disease). We counted the number of times the expressions were accompanied by explanations (crime is like a disease because it spreads by direct personal influence). Similes were more likely than metaphors to be accompanied by explanations. Similes may be preferred if a writer wants to express an out-of-the-ordinary relation between the topic and the vehicle.

Concept Formation↗
PubMed2006

Blind man draws using diminution in three dimensions.

Can the principle of convergence in three spatial dimensions be reflected in drawings by the congenitally blind? A man who had been totally blind since birth was asked to draw scenes such as a tabletop with three cubes receding to the observer's left side. He used converging lines to show the tops of the cubes receding in depth. He drew the cubes to the left smaller than the cube in front of the observer. He drew faces of cubes to the left with tilted lines, pointing to below the front face of the cube in front. The result approximates three-point perspective. We note that the directions of objects from a vantage point in touch converge much as they do in vision.

Blindness↗
PubMed2004

Line at shape-from-shadow border tested with stereo.

Kennedy and Bai (2000 Perception 29 399-408) argued incorrect border polarity blocked perception of faces in shape-from-shadow 'Mooney faces' with dark lines at the contour, a display inspired by Hering. Their hypothesis was tested with several displays, notably binocular gratings made of lines of dots. The stereo-induced depth involved a shadow falling on two surface planes. Most of a dark-dotted (shadow) region appeared to be on one surface, but a strip of dark dots at the shadow's border appeared to be on another-to the fore or rear. Control conditions involved 'negative' images (white dots). Subjects saw the shadowed object as easily in dark-dotted images with stereo depth as in an image with uniform depth for all the dots, and more readily than in the negatives. Our results favour the border-polarity hypothesis.

Adult↗
PubMed2003

Establishing an ethical climate in support of research integrity: efforts and activities of the American Sociological Association.

The article provides an overview of the recent efforts and activities of the American Sociological Association (ASA) to keep its Code of Ethics visible and relevant to its membership. The development process and challenges associated with the most recent revision of the ASA's code are reviewed, the current education and support activities are described, and other strategies for taking a proactive and leadership role in establishing an ethical climate are proposed. In conclusion, while the ASA has made significant progress in this area, it recognizes that a lot of work remains.

Codes of Ethics↗
PubMed2003

Haptics and projection: drawings by Tracy, a blind adult.

Outline drawings in a raised form were made by a blind woman, Tracy, who has been blind from very early in life. Highly practiced in drawing, she reports she is largely self-taught. To invoke matters of projection, she was asked to represent an object with faces slanting away from the observer, a fixed array from different vantage points, and sets of objects in depth. In particular, she drew a cube balanced on a vertex, three objects from different vantage points, receding rows of glasses, and a house. Her drawings included features of parallel and polar projection. Her use of these features may reflect an appreciation of direction from a vantage point, which observers deal with via haptics in everyday tasks. Tracy may have advanced drawing-development skills common to the blind and the sighted.

Adult↗
PubMed2003

Drawings from Gaia, a blind girl.

Gaia, a totally blind girl, was asked to make raised-line drawings. Gaia's vision at best was peripheral. She draws out of interest, and has drawn since preschool with encouragement from her mother. She was asked to draw objects and scenes involving depth from a vantage point, eg a table from below, two cars (one behind the other), and two parallel rows of apples (receding from her, on a table top). Gaia represented space in her drawings using T-junctions for overlap, height in the picture plane, parallel projection, and inverse projection. That is, Gaia uses features of systems common in sighted children's drawings. The development of drawing in blind and sighted children may be similar in good measure because haptics provides access to many of the same spatial principles as vision.

Adolescent↗
PubMed2002

Progressive failure analysis of laminated composite femoral prostheses for total hip arthroplasty.

In this research program, a numerical method was developed to predict the progressive failure of a thick laminated composite femoral component for total hip arthroplasty. A 3-D global/local technique was used to capture the overall structural response of this system while also enabling the 3-D ply level stress state to be determined efficiently and accurately. Different failure criteria and different material degradation models were incorporated as individual subroutines in the numerical method, giving it the flexibility to model a wide range of materials and structures. Numerical modeling was also conducted to design experimental test methods for component fatigue testing that closely simulate in vivo loading conditions. Parametric studies were then conducted with the numerical model of the experimental system and the results were compared to the actual experimentally determined damage behavior of fabricated laminated composite femoral component to assess which parameter set most accurately predicted the actual damage development behavior. The best fitting parameter set was then applied to the failure problem of the composite hip prosthesis implanted in an anatomically modeled femur to predict in vivo performance. This work provides a ply level understanding of the damage behavior of laminated composite femoral components and a numerical tool which can serve as a guide for the design of fatigue resistant implants made from composite material for this and other implant applications.

Arthroplasty, Replacement, Hip↗
PubMed2002

Haptic pictures: fit judgments predict identification, recognition memory, and confidence.

DAngiulli et al (1998 Scandinavian Journal of Psychology 39 187-190) found blind and sighted (blindfolded) children identified common objects in raised-outline drawings explored haptically, and corrected themselves without feedback. The self-correction suggests that participants can assess the extent to which the referents they suggest as possible identifications fit the haptic pictures. Indeed, when we asked subjects to identify haptic pictures, and to judge how well the referents they mentioned fitted the pictures, their fit judgments predicted the accuracy of their suggestions. Also, when one group of subjects offered the suggestions and another group assessed the fit of the suggestions to the pictures, the fit judgments predicted the accuracy of the suggestions. Further, good fit predicted successful recognition memory. In addition, both high and low fit judgments were made confidently, so the range of confidence judgments was smaller than the range of fit judgments. Finally, visual judgments of fit by one group predicted the level of success of the suggestions from another (haptic) group. In sum, subjects assess their suggested identifications appropriately, most likely on the basis of object shape criteria, outlined surface edges, and use of a vantage point.

Blindness↗
PubMedDate not supplied

Clinical case of the month. Severe progressive weakness in a 58-year-old man. Myasthenia gravis.

Myasthenia gravis historically has been associated with significant morbidity and mortality rates, and most of those afflicted either died of the disease or became greatly disabled. However, modern understanding of the pathogenesis of this disorder has led to several effective treatments which have transformed the prognosis of this disease greatly.

Diagnosis, Differential↗
PubMedDate not supplied

Failure analysis of composite femoral components for hip arthroplasty.

In this research, a numerical method was developed for predicting the progressive failure of thick laminated composite femoral components. A three-dimensional (3-D) global/ 3-D local technique was developed to capture the overall structural response of this system, while also enabling the 3-D ply-level stress state to be determined efficiently and accurately. Different failure criteria and material degradation models were incorporated in the method, giving it the flexibility to model a wide range of materials and structures. Numerical modeling was also conducted to design experimental test methods to simulate in vivo loading conditions for component fatigue tests. Parametric studies were then conducted with the numerical model of the experimental system. Next, we compared the results to the damage behavior of the experimentally determined laminated composite femoral component to assess which parameter set most accurately predicted the actual damage development behavior. We then applied the best-fitting parameter set to analyze simulated in situ composite femoral components. Results showed that this methodology efficiently and accurately predicted damage initiation and propagation. This research demonstrates how analytical and numerical models may be used before conducting extensive experimental tests as initial tools to evaluate components for the design of composite hip implants that possess a high level of damage resistance and damage tolerance.

Equipment Failure Analysis↗