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Biomedical subjects

R Kimchi

Publications and source records attributed to R Kimchi.

At least 19 recordsLinked to original sources
PubMed2000

The perceptual organization of visual objects: a microgenetic analysis.

Primed matching was used to examine the microgenesis of perceptual organization for line configurations that vary in the connectedness between their four line components, and for hierarchical patterns composed of four outline closed figures. The results for the line configurations showed that the configural organization of the disconnected line segments was available for priming very early, and its effect outweighed possible effects of the line components. An early relative dominance of the components was observed for the stimuli whose components were closed figures. These results suggest that uniform connectedness is not necessary for the designation of entry-level units. Disconnected line segments are rapidly organized into configurations, provided the presence of collinearity and/or closure. Closed figural elements are individuated early and are grouped into higher-level units with time.

Adolescent↗
PubMed2000

Relative judgment seems to be the key: revisiting the Beck effect.

In multiple-stimulus presentation, orientation disparity has been known to be more discriminable than disparity in line arrangement (e.g., J. Beck, 1972). The source of the effect and its locus were studied in 7 experiments. In different experiments a discrimination between an upright T and either a tilted T or an L, or a discrimination between a tilted T and an L, was required, either in a single stimulus presentation or in the context of upright Ts. Number of stimuli, location uncertainty, and adjacency between stimuli were manipulated. The results indicated that the effect is insensitive to these factors, which is incommensurate with predictions from several accounts of the effect. All the effect requires is that disparate stimuli are simultaneously presented, suggesting that relative judgment is a necessary condition for its manifestation. The effect surfaces when the task calls for procedures based on perception of homogeneity or salience.

Adult↗
PubMed2000

Guardianship for the severely mentally ill.

The process of appointing a guardian in the mental health field is a complex and important one. The guardian's duty is to protect a patient who is incompetent in making his own decisions. The guardian's role can be to correct past mistakes made by the patient (i.e. loss of property), manage the patient's present affairs and prevent future undesirable consequences. Characteristics of patients who are in need of guardianship have not previously been studied in Israel. We examined the characteristics of 60 hospitalized patients for whom a guardian was appointed, comparing them with another group of patients. Variables relating to disease severity such as diagnosis, duration of illness and employment status contrasted the groups. We may tentatively conclude that patients in need of legal guardianship are more severely ill than other mentally ill.

Adult↗
PubMed1997

Insight and competence to consent to psychiatric hospitalization.

Informed consent and insight are among the most important issues in medical treatment, especially for psychiatric patients. In this study, we examined the competence to consent to psychiatric hospitalization of 113 psychiatric patients who were voluntarily admitted to a mental hospital in various psychotic states and compared it with their insight. We found a significant correlation between the patients' competence and insight into their illnesses. There is a discussion of the problematic issues of informed consent, competence and psychosis and the importance of insight in the context of mental illness.

Adult↗
PubMed1994

[Attitudes of courts, physicians and psychiatric committees to court-ordered psychiatric hospitalization].

Legal responsibility for the mentally ill has long been a dilemma. Public opinion with regard to the current law, which holds that the mentally ill are not responsible for their actions, is divided. We assessed 30 cases of psychiatric patients committed by court order following a criminal act. No relation was found between the nature of the transgression and the nature or seriousness of the psychiatric disorder. Interestingly, those who committed the more serious crimes, such as murder, usually had committed fewer criminal acts in the past. The functioning of the psychiatric committees in charge of releasing patients committed by court order has improved substantially under the new law for the treatment of the mentally ill. They now assess patients with considerably greater frequency. The reports to the courts of examining physicians tend to be general, with little attempt to differentiate ability to stand trial and responsibility for actions. On the other hand, treating physicians relate mainly to the patient's illness, rather than to the crime for which he was committed.

Attitude↗
PubMed1994

The role of wholistic/configural properties versus global properties in visual form perception.

A distinction has previously been proposed between global properties, defined by their position in the hierarchical structure of the stimulus, and wholistic/configural properties defined as a function of interrelations among component parts. The processing consequences of this distinction were examined in five experiments. In experiments 1-4 configural properties (closure and intersection) were pitted against component properties (line orientation and direction of curvature) and the results showed that discrimination and classification performance was dominated by the configural properties. In experiment 5 the relative perceptual dominance of type of property (configural/nonconfigural) and level of pattern structure (global/local) was examined. The results showed that classifications based on the configural property of closure were not affected at all by the level of globality at which this property varied. Global advantage was observed only with classifications based on line orientation. Taken together, the present results suggest that configural properties dominate discrimination and classification of visual forms, whereas the perceptual advantage of the global level of structure depends critically on the type of properties present at the global and local levels. These findings are also discussed in relation to findings on texture perception, and it is suggested that the perceptual system may be characterized by a predisposition for configural properties.

Adult↗
PubMed1993

Performance under dichoptic versus binocular viewing conditions: effects of attention and task requirements.

Three experiments investigated subjects' ability to allocate attention and cope with task requirements under dichoptic versus binocular viewing conditions. Experiments 1 and 2 employed a target detection task in compound and noncompound stimuli, and Experiment 3 employed a relative-proximity judgment task. The tasks were performed in a focused attention condition in which subjects had to attend to the stimulus presented to one eye or field (under dichoptic and binocular viewing conditions, respectively) while ignoring the stimulus presented to the other eye or field, and in a divided attention condition in which subjects had to attend the stimuli presented to both eyes or fields. Subjects' performance was affected by the interaction of attention conditions with task requirements, but it was generally the same under dichoptic and binocular viewing conditions. The more dependent the task was on finer discrimination, the more performance was impaired by divided attention. These results suggest that at least with discrete tasks and relatively short exposure durations, performance when each eye is presented with a separate stimulus is the same as when the entire field of stimulation is viewed by both eyes.

Adult↗
PubMed1992

Primacy of wholistic processing and global/local paradigm: a critical review.

The question of whether perception is analytic or wholistic is an enduring issue in psychology. The global-precedence hypothesis, considered by many as a modern version of the Gestaltist claim about the perceptual primacy of wholes, has generated a large body of research, but the debate still remains very active. This article reviews the research within the global/local paradigm, and critically analyzes the assumptions underlying this paradigm. The extent to which this line of research contributes to understanding the role of wholistic processing in object perception is discussed. It is concluded that one should be very cautious in making inferences about wholistic processing from the processing advantage of the global level of stimulus structure. A distinction is proposed between global properties, defined by their position in the hierarchical structure of the stimulus, and wholistic properties, defined as a function of interrelations among component parts. It is suggested that a direct comparison between processing of wholistic and component properties is needed to support the hypothesis about the perceptual primacy of wholistic processing.

Attention↗
PubMed1991

Hemispheric processing of global form, local form, and texture.

Hemispheric processing of global form, local form, and texture of hierarchical patterns composed of many, relatively small elements and patterns composed of few, relatively large elements was examined in two experiments, employing a Stroop-type paradigm. In experiment 1 subjects were instructed to attend either to the global or the local level of the pattern and to identify the form at the designated level. In experiment 2 subjects were to identify the global form or the texture. A right visual field (left hemisphere) advantage was obtained for detection of local form, and a left visual field (right hemisphere) advantage was obtained for detection of global form. When many-element patterns were processed in terms of global form and texture, the results failed to show reliable hemispheric differences. The results suggest that the hemispheres differ in their sensitivity to the relatively more global versus the relatively more local aspects of visual patterns which require focused attention (as in global/local form detection). When the task involved distributed attention (as in texture detection) no lateralized effects were observed.

Adolescent↗
PubMed1991

Recognition of rotated letters: extracting invariance across successive and simultaneous stimuli.

Response time (RT) for identifying single letters is usually indifferent to disorientation, but in Experiment 1 RT increased with the angular deviation from that of the preceding letter (ADP). This occurs only when the same letter is repeated, which suggests a process of backward alignment. RT again increased with ADP when the same letter was repeated in the same format (normal or mirror-reflected: Experiment 2). These findings were replicated for a same-different task by using 2 simultaneously presented letters (Experiment 3). Experiments 4 and 5 focused on stimuli that are related by a rotation in depth and suggested that transformation in the depth plane may facilitate judgments of sameness and that backward alignment can occur for different views of the same three-dimensional shape. The results suggest the operation of a pattern-recognition mechanism that relies on the extraction of invariance over temporally or spatially contiguous events.

Adult↗
PubMed1985

Separability and integrality of global and local levels of hierarchical patterns.

We used a constrained classification task to examine the perceptual relations between global and local levels in hierarchical patterns composed of many, relatively small elements and those composed of few, relatively large elements. In Experiments 1 and 3 subjects were asked to make classifications based on "form" or "texture." In Experiments 2 and 4 they were asked to classify according to the "shape" of the configuration or the elements. The results indicate that configural and elemental levels are perceptually separable for many-element patterns when processed as form and texture: Subjects could attend to either level without being affected by variation along the irrelevant dimension. However, when the same many-element patterns were processed for global and local shape, subjects could not selectively attend to either level. For few-element patterns, global configuration and local elements appeared to be perceptually integral dimensions. These results are relevant to two issues: the global precedence hypothesis and the explanations of integral and separable dimensions.

Adolescent↗
PubMed1983

Effect of interferon on the formation and release of intracellular virions in NIH/3T3 cells chronically infected with Moloney murine leukemia virus.

Using transmission electron microscopy, we demonstrate in this study the existence of intracellular Moloney murine leukemia virus particles in cytoplasmic vacuoles of chronically infected NIH/3T3 cells. Interferon (IFN) treatment for 48 h resulted in a 3-fold higher accumulation of these vacuolar virions. Intracellular virions and their accumulation in IFN-treated cells could also be shown by radioactive labeling of the cells for 48 h and isolation of labeled virus particles from the cytoplasmic fraction of the cells by banding in sucrose gradient. These virions contained typical viral RNA, proteins and glycoproteins, as determined by gel-electrophoresis. Despite their higher accumulation, the formation rate of the intracellular virions, as measured by their pulse labeling for 1 h with S35-methionine, was found to be remarkably lower in IFN-treated cells. In order to elucidate this discrepancy, we followed the kinetics of the intracellular and extracellular virus appearance. We found that the inhibitory effect of IFN on the release of virus particles to the culture medium was much stronger than its effect on the formation of the intracellular virions. This finding can explain the accumulation of intracellular virus particles in IFN-treated cells despite their reduced formation rate.

Animals↗
PubMed1982

Form and texture in hierarchically constructed patterns.

Perceived organization of hierarchically constructed patterns was investigated through similarity judgments and a verbal description task. The number of elements and their sizes relative to the configuration were varied in a series of five experiments. The results show that in patterns composed of a few relatively large elements, the elements are perceived as individual parts of the overall form and are perceptually salient. Increasing the number of elements and/or decreasing their size results in a perceived unified form associated with texture, representing the structural properties of the elements as a group. In the latter case, the perceptual salience of the individual element decreases and the global form (or sometimes the texture) dominates perception. These findings suggest that the perceptual levels arising from global configuration of local elements may not correspond directly to these two geometrical levels in the stimulus domain as much previous work on "global versus local" processing has assumed. Rather, the mapping of the two independent geometrical levels into meaningful perceptual levels depends critically on the number and relative size of the elements, thus changing the perceived organization of the whole pattern.

Adult↗