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R Kimchi

Publications and source records attributed to R Kimchi.

9 recordsLinked to original sources
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↗
PubMed1981

Intracellular production of virus particles and viral components in NIH/3T3 cells chronically infected with Moloney murine leukemia virus: effect of interferon.

The effect of interferon on the biochemical properties and the maturation process of intracellular viral particles isolated from the cytoplasmic fraction of NIH/3T3 cells chronically infected with Moloney murine leukemia virus was investigated. By labeling these virions with either [35S]methionine or [3H]glucosamine, we demonstrated that they contain the same viral proteins and glycoproteins found in extracellular virions. Interferon treatment was found to reduce the rate of intracellular virus assembly. This effect was not a consequence of an interferon inhibition of viral RNA synthesis or its translation or a consequence of an interference with the posttranslational cleavage processing of viral precursor proteins, since all of these steps were not affected by interferon. However, the reduced rate of virus assembly could be attributed to the inhibition of viral protein glycosylation observed in interferon-treated cells. Nevertheless, despite this reduced rate, virus particles accumulated in interferon-treated cells. This accumulation was probably due to the strong inhibition of their final release from such cells.

Animals↗