SEARCH · Search PubMed

Results for “Perceptual Closure”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

SourceResearch connectionFrom yearThrough year

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 19 recordsLinked to original sources

PubMed1990

Priming effects in picture fragment completion: support for the perceptual closure hypothesis.

The perceptual closure hypothesis says that priming will be optimum when just enough information is available in the prime to support closure. Across 5 experiments, a moderately complete fragmented image (Level 4) produced more priming than an almost complete (Level 7) or a very incomplete (Level 1) fragmented image. Only Level 4 priming was improved by increases in prime duration and by showing the prime again after Ss attempted to identify it. Explicit memory played little role in primed fragment completion except for Level 1 priming, in which specific fragment memory was responsible for the entire effect. In contrast, true perceptual learning was shown to be responsible for Level 4 and Level 7 priming. These priming effects cannot be accounted for by the transfer-appropriate procedures approach of Roediger and his colleagues because Level 1 priming produced less transfer to Level 1 identification at test than Level 4 priming did.

Adult↗

PubMed1988

Effects of aging on perceptual closure.

Two research strategies were employed to investigate reasons for the poorer performance associated with increased age on perceptual closure tasks involving the integration and identification of incomplete pictures. One strategy consisted of examining age differences in measures designed to reflect the proficiency of processing components presumed to be involved in the closure task. The performance of older adults was significantly worse than that of young adults on each measure, suggesting that the age differences in the criterion task could not be localized in a single specific component. The second strategy involved determining whether young and old adults differed in the effects of practice or in the amount of specific and general transfer resulting from that practice. No age differences other than those in the overall level of performance were discovered, indicating that the age-associated problem may be independent of the processes contributing to the acquisition and transfer of new information. It was suggested that the age differences in perceptual closure tasks originate because of a general inefficiency in information processing due to a reduction in some type of general-purpose processing resource, and not because of a limitation in a single specific process.

Adolescent↗

PubMed1992

Perceptual closure and object identification: electrophysiological responses to incomplete pictures.

Event-related potentials were recorded during the naming of pictures of concrete objects. The pictures were presented at three levels of completeness: 10, 30, and 60%. The ERP waveforms were evaluated according to the level of picture completeness and the correctness of naming. A negative wave in the latency range of 250-550 ms was significantly more negative when the pictures were more incomplete, regardless of the correctness of response. This N400 wave is proposed as being related to hypotheses about the identity of the object. A late positive wave in the latency range of 550-650 ms followed the negativity, but only when the response was correct. This may reflect the subject's certainty about the perceptual analysis, a verification of the identity of the object. A slow parietal negativity lasting up to 2 sec was largest for the least complete picture. This therefore varied with the perceptual difficulty.

Adult↗

PubMed1987

In search of closure: subjective contour illusions, Gestalt completion tests, and implications.

This study investigates the construct validity of perceptual closure tests (CTs), and isolates a common processing demand from the right-hemisphere. Sixty-seven patients with focal unilateral lesions (34 right side, 33 left side), and 80 control subjects participated. Multivariate analyses indicated that there was substantial age-related variance in all CTs, while sex was variably significant; CTs are not uniform in their discriminating ability, and hence factorially complex; and their specifically right hemisphere-sensitive dimension was subjective contour illusions, and interestingly unrelated to facial discrimination ability. The methodological and theoretical implications are discussed.

Brain Damage, Chronic↗

PubMed1992

[Visual and motor functions in schizophrenic patients].

In the present work, visual and motor functions have been explored in 26 chronic schizophrenic patients, and 7 acute schizophrenic patients, compared with 26 normal controls, by means of the Bender-Gestalt Test. Parameters under consideration were: Form distortion, rotation, integration, perseveration, use of space, subtle motricity, score (global parameter), and time employed. As regards distortion and rotation there have been highly significant differences between chronic patients and control group. Among acute patients, it was observed that perseveration was also highly significant. Conversely, integration and use of space did not differ significantly among the three groups involved. The global score, resulting from all the above mentioned parameters showed important differences between both patient groups on the one hand, and control group on the other hand. Taking into account that patients were being administered neuroleptic drugs, it can safely be said, however, that the Bender-Gestalt Test allows to recognize alteration in perceptual closure consistent with a loss of the objective structure of perceived phenomena, in both chronic and acute patients.

Adult↗

PubMedDate not supplied

Age cohort differences in the ability to perform closure on degraded figures.

Young (17-26) and old (60-80) men and women performed a perceptual closure task for degraded line drawings under three conditions of prior picture knowledge (exact, similar, no prior knowledge) and two conditions of perceptual noise (contour or detail drawings) resulting in six levels of task difficulty. Young and old subjects took equal advantage prior knowledge conditions, however, old subjects required a greater percentage of picture and more time to make closure under all conditions when compared to young subjects. To test the perceptual slowing hypothesis, old subject performance was regressed on that of young across three levels of task difficulty. The slope of these regression equations supported the notion of a perceptual slowing hypothesis to explain age cohort differences.

Adolescent↗

PubMed1986

Flupentixolhydrochloride in low dosages: effects on perceptual and psychomotor performance in emotionally stable and emotionally labile healthy subjects.

Effects of flupentixol on performance were evaluated in a double-blind study with 107 healthy male subjects. Experimental factors were dosage (0, 1, and 2 mg Fluanxol 0.5/day), the trait variable 'neuroticism' (high vs. low score on a questionnaire scale), and time of measurement (before and after 4 days of treatment). Drug effects were measured by means of seven paper-and-pencil tests and eight apparatus tests covering the following cognitive functions: endurance in attention, spacial orientation, flexibility and speed of closure, perceptual speed, response speed, psychomotor coordination, knowledge of traffic rules, and basic motoric tempo. Univariate and multivariate ANOVAs disclosed that flupentixol has detrimental effects on perceptual and psychomotor functions, in particular when administered in a dosage of 2 mg/day. These treatment effects did not interact with the trait variable neuroticism. Nevertheless, there were substantial differences between emotionally stable and emotionally labile subjects in both absolute performance level and change of performance over time.

Adult↗

PubMed1976

Differential diagnosis of psychiatric patients with the Minnesota Percepto-Diagnostic Test.

This study investigated whether normals, personality disorders, psychotics and organics could be differentiated by the Minnesota Percepto-Diagnostic Test. There were significant differences between all the groups except the psychotics and personality disorders. It appears that, in general, perceptual disturbance lies along a pathological continuum. Similar performances of psychotics and personality disorders were discussed.

Diagnosis, Differential↗

PubMed1975

[Experiments on perception in schizophrenia (author's transl)].

Acute and chronic schizophrenic subjects were tested with 6 simple experimental tasks of visual stimulus selection. The 2 control groups were a group of non-psychiatric subjects and one of patients with other psychiatric diagnoses. The 6 experimental tasks represented three different types of attention: 1) differentiation between "figure" and "background", 2) concentration; 3) visual integration (Gestalt completion). The main result was that the acute group with paranoidal psychosis and hallucinations made significantly more mistakes in figure-background differentiation (grouping of patterns). But there was no difference between this group and the other patients in the concentration tasks. Both schizophrenic groups performed more poorly in the Gestalt completion task. The results are discussed in light of the information theory (breakdown of a hypothetical filter mechanism) and Sokolow's psychophysiological model of stimulus selection. The hypothesis is put forward that in the acute schizophrenic group a disturbance in an arousal-modulation system is responsible for attenuation of irrelevant input.

Acute Disease↗

PubMed1992

A good-continuation model of some occlusion phenomena.

Occlusion phenomena raise two questions: (1) When will an occluding and a partly occluded object be seen, as opposed to several nonoverlapping objects? (2) What is seen behind the occluding object? Available theories give no satisfactory description of occlusion data. In our view, this situation is at least partially due to the fact that patterns used in occlusion studies are always regular, whereas it is almost unknown which regularities are actually perceived in occlusion patterns. We have therefore collected a complete set of data for a restricted domain of patterns with minimal regularity. Starting from these data, we have developed a model of the perceptual organization of this class of patterns and tested it in a second experiment. The model is a specification of the Gestalt law of good continuation. It assumes that there is a tendency to describe a pattern by the smallest possible number of contour elements and with the smallest possible changes of direction within and between necessary contour elements. The results fit in well with the predictions of the model. It is further demonstrated that the model also describes the preferred interpretations of many regular patterns, published in other studies.

Adult↗

PubMed1989

The effects of kinetic occlusion and categorization on amodal completion. A comment on Gerbino and Salmaso (1987).

The experimental study of Gerbino and Salmaso (1987) focused on the process of amodal completion, i.e. the process that leads to the impression of a total pattern in the absence of information about all parts of the pattern. One of the questions that they have attempted to answer with respect to this process is whether or not it depends on the categorization of the modal part (i.e. the part about which visual information is present) as a modification of a complete prototype. The major conclusion of their experiments is that amodal completion does not depend upon categorization. Furthermore, they interpret their results as indicating that neither the truncated form of the occluded part nor the unification/segregation of contour segments are phenomenally real. We designed some variants of the tunnel effect to demonstrate (1) that the explicit categorization of some parts of the input can have an influence on amodal completion and (2) that the truncated form of a pattern can be phenomenally real. Our results corroborate these hypotheses and can, therefore, interpreted as refuting two rather central claims of Gerbino and Salmaso (1987). The conclusion of our experiment must be that amodal completion is not as primary as they have supposed but can be influenced by kinetic occlusion and categorization stored in visual memory.

Adult↗

PubMed1990

Object superiority: a comparison of complete and part probes.

Previous research on object superiority effects has shown that certain contexts enhance the recognition of an object part. However, those contexts would not normally be called objects. The present study discusses object superiority within more general issues of object recognition. By using what we call 'complete' probes, superiority effects were extended to exposure durations much longer than those used in previous research. Experiments 1 and 2 found that complete probes gave stable superiorities at 250 msec and even 2-sec stimulus exposures. These object superiority effects were found for both objects (faces and chairs) investigated. Experiment 3 showed that object superiorities established with complete probes were not necessarily greater than those for part probes. The experiments stress the role of spatial arrangement of object parts in accessing stored information. It is argued that a successful match of a structural description to a representation in long-term memory influences stimulus processing by allowing the formation of higher level features.

Adult↗

PubMed1992

Global shape cannot be attended without object identification.

Whether the global shape of objects can be processed without accessing semantic or identity information was tested. Ss judged which of 2 fragmented forms had the same global shape as a reference stimulus. Matching stimuli could be physically identical, semantically related, or unrelated. The reference stimulus and nonmatching (distractor) form could be semantically related or unrelated. Similarity effects in the related condition were unconfounded with matches nameable and nonnameable forms. For nameable forms, related matching forms facilitated performance; a related distractor disrupted performance. Semantic interference was eliminated when nameable distractors were replaced with nonnameable partners; semantic similarity effects on matching were eliminated with a nonnameable reference stimulus and with inverted targets and distractors. Access to information concerning global shape does not normally occur without object identification.

Adult↗

PubMed1978

Perception and masking of wholes and parts.

These exerpiments show that the effects of masking on reports of target lines depend on the context in which the target lines appear. Subjects viewed brief presentations of target lines either alone or in drawings of three-dimensional objects, and each target display was preceded and followed by one of several different mask stimuli. There were two main findings: (a) A mask containing a haphazard array of lines interfered more with single lines than it did with lines in objects. (b) A mask containing drawings of the object displays interfered more with lines in objects than did either of two control masks containing relatively flat, less coherent patterns. In a control condition, the object mask interfered slightly less with reports of single lines than either of the control masks did. The discussion considers how the effects obtained here bear on models of the processing of wholistic stimuli and their component parts.

Discrimination, Psychological↗

PubMed1990

Sensitivity to the displacement of facial features in negative and inverted images.

Subjects have previously been reported to show difficulties in recognising faces which are either inverted or in photographic negative. Experiments are reported in which a two-alternative forced-choice technique was used to measure sensitivity for distinguishing faces which have been modified by having the eyes moved vertically or horizontally. Subjects were less sensitive to such changes for inverted faces or negative faces, and were even less sensitive for faces that were both inverted and negative. No such effects were found for a control stimulus consisting simply of three solid circles in the same positions as the eyes and mouth of a face. When the stimuli consisted of eyes, nose, and mouth, but without a surround, no evidence of inversion or negation effects was found, which suggests that a facial surround is necessary. When the stimulus consisted of a facial surround with the eyes, nose, and mouth replaced by solid circles, effects of negation were found, but no effects of inversion. This dissociation of the effects of negation and inversion may suggest that they are the result of different underlying mechanisms.

Adult↗

PubMed1979

The influence of stroke on visual illusion magnitude.

In an attempt to resolve contradictory reports about the effect of right-versus left-hemisphere damage on perception of the Mueller-Lyer illusion, the present study examined judgments of stroke patients using this and several other visual illusions. The results provide some indication of abnormal perception of the Mueller-Lyer by patients with left-hemisphere damage. But the overall magnitude of illusion was normal in both groups of patients. It is possible that stroke damage did not affect the brain areas that are responsible for "gestalt" synthesis. However other recent studies using the Mueller-Lyer suggest that actual or incipient eye movements play an important role in the perception of this illusion, and under some conditions of testing, it is the activity of the left hemisphere that determines illusion magnitude.

Brain Mapping↗

PubMedDate not supplied

Object recognition by component features: are there age differences.

This study extended aspects of Biederman's (1987) recognition-by-components (RBC) theory to the analysis of age differences in the recognition of incomplete visually-presented objects. RBC theory predicts that objects are recognizable or recoverable under conditions of fragmentation if a sufficient amount of essential structural information remains available. Objects are rendered nonrecoverable by the omission or obstruction of essential structural features at vertices and areas of concavity. Fifteen young adults and 15 older adults participated in a study of the effects of amount (25%, 45%, 65%) and type of fragmentation (recoverable, nonrecoverable) on object naming. Age-related declines in recognizing incomplete objects were associated with the amount of fragmentation, but type of fragmentation did not affect the performance of older adults. For the young adults, accuracy of performance was affected by both amount and type of fragmentation, consistent with Biederman's RBC theory. These results were interpreted as suggesting that age-related declines in perceptual closure performance have to do with non-structural factors such as the ability to inferentially augment degraded or missing visual information.

Adolescent↗

PubMed1975

Psychopathology scale of the Hutt adaptation of the Bender-Gestalt Test: reliability.

The test-retest reliability of the Hutt Adaptation of the Bender-Gestalt test was explored with a population of 40 process schizophrenics over a two-week interval. The total Psychopathology Scale Score was found to have high retest reliability for both male and female patients (rho = .87 for males and .83 for females). Moreover the three major components for the Scale were found to have high reliability, and fairly high reliabilities were obtained for patients scoring high as well as low on the Scale. Interjudge reliability was also found to be very high (rho = .895), confirming previous studies in this respect. On these grounds, the Scale offers promise both for clinical and research purposes.

Adult↗