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At least 55 records · Page 3Linked to original sources
PubMed1993

Comparison of fixation disparity measurements obtained with the Wesson Fixation Disparity Card and the Sheedy Disparometer.

We compared the fixation disparity measurements obtained with the Disparometer to those of the Wesson Card. Previous studies suggest that the measurements obtained by these two instruments gave different results. The results of previous studies were based on the analysis of pooled data, which may have led to spurious results. Analysis of our data done in this manner (pooled data) revealed the same findings. However, after analysis of the data based on the separation of subjects according to phoria (exophoria/esophoria), no statistically significant difference was found between the measurements obtained with the Wesson Card and those with the Disparometer.

Adult↗
PubMedDate not supplied

Damage compounded: disparities, distrust, and disparate impact in end-of-life conflict resolution policies.

For a little more than a decade, professional organizations and healthcare institutions have attempted to develop guidelines and policies to deal with seemingly intractable conflicts that arise between clinicians and patients (or their proxies) over appropriate use of aggressive life-sustaining therapies in the face of low expectations of medical benefit. This article suggests that, although such efforts at conflict resolution are commendable on many levels, inadequate attention has been given to their potential negative effects upon particular groups of patients/proxies. Based on the well-documented tendency among many African Americans to prefer more aggressive end-of-life medical interventions, it is proposed that the use of institutional policy to break decision making impasse in cases for which aggressive treatment is deemed "medically inappropriate" will fall disproportionately on that group. Finally, it is suggested that the development and application of institutional conflict-resolution policies should be evaluated in the context of historical and current experiences of marginalization and disempowerment, lest such policies exacerbate that experience.

Black or African American↗
PubMed2004

Disparate systems, disparate data: integration, interfaces, and standards in emergency medicine information technology.

As part of the broader informatics consensus initiative sponsored by Academic Emergency Medicine, this report addresses the issues of integration, interfaces, and data standards and how they are relevant to information management in emergency medicine. The purpose of this report, and the workgroup that contributed to its content, is to provide emergency physicians and other stakeholders in the emergency informatics community a sense of direction as they design, build, and/or choose systems. Problems are identified, strategies to address these problems are discussed, and consensus recommendations are provided.

Emergency Medicine↗
PubMed1997

Types of size disparity and the perception of surface slant.

We examined (i) perceived slant of a textured surface about a vertical axis as a function of disparity magnitude for horizontal-size disparity, vertical-size disparity, and overall-size disparity; and (ii) interactions between patterns with various types and magnitudes of size disparity and superimposed or adjacent zero-disparity stimuli. Horizontal-size disparity produced slant which increased with increasing disparity, was enhanced by superimposed zero-disparity stimuli, and induced contrasting slant in superimposed or adjacent zero-disparity stimuli. Vertical-size disparity produced opposite slant (induced effect) which was reduced to near zero by a superimposed zero-disparity pattern and both patterns appeared as one surface. Adjacent vertical-size-disparity and zero-disparity patterns appeared as separate surfaces with a wide curved boundary. Overall-size disparity produced slant which was enhanced by a superimposed zero-disparity pattern and less so by a zero-disparity line, and induced more slant in a zero-disparity line than in a zero-disparity pattern. The results are discussed in terms of depth underestimation of isolated surfaces, depth enhancement, depth contrast, and the processing of deformation disparity.

Adult↗
PubMed1998

Types of shear disparity and the perception of surface inclination.

A study is reported of (i) the perceived inclination of a textured surface in depth about a horizontal axis as a function of disparity magnitude for horizontal-shear disparity, vertical-shear disparity, and rotation disparity; and (ii) interactions between patterns with shear or rotation disparity and superimposed or adjacent patterns or lines with zero disparity. Horizontal-shear disparity produced strong inclination which was enhanced by superimposed or adjacent zero-disparity stimuli. It produced little or no inclination contrast in superimposed or adjacent zero-disparity stimuli. Vertical-shear disparity produced inclination in the opposite direction (induced effect) which was reduced to near zero by a superimposed zero-disparity pattern. Adjacent vertical-shear and zero-disparity patterns appeared inclined at slightly different angles with a wide curved boundary. This suggests that vertical-shear disparities are averaged over a wide area. Rotation disparity produced minimal inclination. A superimposed or adjacent zero-disparity line appeared strongly inclined. A superimposed or adjacent zero-disparity pattern appeared vertical and caused the pattern with rotation disparity to appear inclined. Four mechanisms are proposed to account for the results: depth contrast, depth enhancement, deformation-disparity processing, and disparity transfer arising from cyclovergence.

Computers↗
PubMed1987

Adaptation of ocular vergence to stimulation with large disparities.

Ocular vergence movements were measured with a scleral coil technique under stabilized viewing conditions for disparity. Crossed disparity steps, ranging between 0.25 and 10 deg, of three different targets were imposed. Ocular vergence responses consisted of converging movements with an initially constant velocity. This velocity increased with the magnitude of disparity up to about 4 deg and decreased for larger disparities. For disparities up to 2 deg the responses saturated at the limit of convergence. For larger disparities responses were transient, i.e. after large converging movements the angle of convergence gradually declined to about its initial value. For disparities larger than 5 deg amplitudes of the transient responses decreased and occasionally responses were completely absent. The transient character of responses was apparently due to adaptation of the vergence system to a specific disparity, since responses to different disparities could still be induced. Probing of the vergence system with two successive disparity steps of different magnitudes showed that adaptation was selective for a limited range of disparities around the adapting disparity stimulus. Stabilized disparity pulses with durations ranging from 100 to 800 ms induced ocular vergence movements following the time integral of disparity rather than momentary disparity. This indicated that the part of the vergence system sensitive to disparity has mainly integrative properties for large as well as small disparities. Stimulation with trains of shortlasting disparity pulses showed that adaptation also occurred under normal viewing conditions. They further revealed that adaptation is erased during a short period after each blink.

Adaptation, Ocular↗
PubMed2004

[An event-related potential study the on information processing of binocular disparity in random-dot stereogram].

OBJECTIVE: To study the effects of discontinuous-continuous disparity gradient, uncrossed-crossed disparity and small-large disparity in random-dot stereogram (RDS) on the event-related potentials (ERPs). METHOD: Behavioral data and ERP were recorded when 16 healthy participants (8 males and 8 females) with normal depth perception were performing the task, in which the stereopsis were generated by red-blue glasses. RESULT: 1) The accuracy in discontinuous disparity gradient was higher than that in continuous disparity gradient, and the accuracy in large disparity was higher than that in small one. 2) Discontinuous disparity gradient elicited shorter N160 latency and larger N350 amplitude than continuous disparity gradient did. Compared with uncrossed disparity, crossed disparity elicited shorter N350 latency. In addition, large disparity elicited shorter N160 latency and larger P280 amplitude than small disparity did. CONCLUSION: The effect of disparity gradient on disparity information processing is significant, and the discontinuous disparity gradient has its processing advantage. Latency of N160 and amplitude of P280 is correlated with the information processing of the size of disparity. N350 component is correlated with the information processing of the uncrossed-crossed information of disparity.

Adult↗
PubMed2003

Detecting disparity in two-dimensional patterns.

One can measure the disparities between two retinal images in several different ways. Experiments were conducted to identify the measure that is invariant at the threshold for detecting the disparity of two-dimensional patterns. The patterns used were stereo plaids, which permit a partial dissociation between the disparity of the pattern and the disparities of its one-dimensional components. For plaids with near-horizontal disparities, thresholds are limited by a disparity phase shift equal to the threshold phase shift for single gratings. For non-horizontal disparities, thresholds are elevated, yet are still phase-limited. In no disparity direction are thresholds for detecting disparity determined by the spatial extent of the plaids' disparity. Effects of the number and the orientation of components with task-relevant disparities indicate that plaid thresholds are limited by the disparity of the plaid's one-dimensional components. No evidence was found that these components form any higher-order pattern that can be used in detecting disparity. Oblique and near-vertical disparities generate elevated thresholds at a stage beyond component disparity detection. This second stage combines component disparities, which are ambiguous about depth, into pattern disparities capable of supporting veridical depth perception.

Humans↗