A factor analytic study of the Frosting Developmental Test of Visual Perception.
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Factor Analysis, Statistical↗
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Perception-action coupling during bimanual coordination: the role of visual perception in the coalition of constraints that govern bimanual action.
Constraints pertaining to interlimb coordination have been studied extensively in the past decades. In this debate, F. Mechsner (2004) has taken a provocative position by putting primary emphasis on perceptual principles that mediate coordinative stability. Whereas the present authors agree that the role of perceptual principles is of critical importance during coordination, they take issue with Mechsner's extreme position and with the evidence forwarded to support a purely perceptual-cognitive approach to bimanual coordination. More specifically, the authors emphasize that current knowledge about brain function argues against a dualism between perception and action, criticize the presented evidence that posture manipulations during coordination provide decisive evidence against motoric and muscular constraints, and report on potential pitfalls associated with the use of visual transformation procedures to support complex coordination patterns.
Hand↗
[Interhemispheric relations in the process of visual perception in schizophrenic patients].
The purpose of the performed study was to compare the time of visual stimuli perception for different hemispheres in normals and in schizophrenic patients. In normals there was a certain asymmetry in the speed of perception of letter stimuli between the right and left hemispheres. It was established, that in the right hemisphere there was a more rapid perception of the letters as compared to the left one. In schizophrenic patients there is no interhemispheric differences in the time of perception, owing to the fact that the right hemisphere loses the advantage in speed of processing visual information. The author makes an assumption of the possible role of disturbed activity of the right hemisphere in the psychopathological symptomatology.
Adolescent↗
Abnormal psychophysical visual perception in Parkinson's disease patients.
Several visual dysfunctions in Parkinson's disease (PD) are described. Most of them are subtle or only demonstrated by stimulus-specific electrophysiologic or psychophysical testing. However, these minor deficits are thought to be of clinical relevance as they are related to direct or indirect complaints. Special emphasis is laid on visual hallucinations. These are most likely of multifactorial origin. The relation between hallucinations in PD and in dementia with Lewy bodies has to be elaborated further. Visual loss, as a possible and reversible cause of visual hallucinations should be actively sought and corrected as far as possible. An underlying role of dopaminergic retinal cells in visual dysfunction of PD patients is widely recognised. However, whether the basic abnormality resides also in the visual cortex remains to be elucidated. Other neurotransmitters may also be involved. It has not been answered whether visual dysfunction might distinguish PD from other forms of parkinsonism.
Animals↗
Relativistic effects in visual perception of real and apparent motion.
Timing in the visual field is regarded as an additive conjoint measurement structure, psychophysical extension of stimulus path as an extensive measurement structure. These two sets of postulates lead to the derivation of an essential maximum for velocity perception. Apparent phi motion perception under strictly stationary stimulus conditions is described as relative motion of the first stimulus' psychophysical mapping with respect to a moving perceptual subsystem. The essential maximum of velocity modifies the relative motion postulate: relativistic dilatation of seen length of path is predicted. Testable properties of the model, comparison with experimental data from "real" motion and apparent phi motion perception are discussed.
Humans↗
Activation of area V5 by visual perception of motion demonstrated with echoplanar MR imaging.
Cortical activation in visual association areas known to be responsible for the perception of motion was investigated in two volunteers who viewed a projected animated cartoon periodically "run" and "frozen" during collection of echoplanar MR images. Ten axial, contiguous, 5 mm thick, T2-weighted, gradient-echo images (TE 40 ms, TR 3000 ms) depicting BOLD contrast were acquired through the occipital lobe using a GE Signa 1.5 T system with an advanced NMR operating console. Images were analysed by time series regression modelling estimating power in the MR signal at the ON-OFF frequency of motion. Highly significant activation in response to motion perception was identified in both subjects bilaterally in area V5.
Echo-Planar Imaging↗
[Central disorders of visual perception].
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Central Nervous System Diseases↗
Pattern evoked average EEG potentials and dichoptic visual percepts.
Monocular xenon flashes were used to evoke average EEG potentials while blank, dot or grid targets were shown simmultaneously in ten dichoptic stimulus conditions, either continuously illuminated (added to the flashes, or contraocularly), or presented only by the flashes. Mean evoked-EEG-potential waveforms over repeated conditions were computed from average evoked potentials (EPs) for each stimulus condition and each hemisphere. Correlation coefficients were computed between mena-EP waveforms of all stimulus condition for each subject. Mean correlation coefficients over subjects were treated in a cluster analysis to diagnose conditions associated with similar EP waveforms. Data from the two hemispheres yielded identical cluster results. Presence or absence of continuous target illumination for the flashed eye was the most powerful descriptor. Next important was continuously visible structure (regardless whether seen by the flashed or the nonflashed eye) in conditions with continuous illumination seen by the flashed eye, and flashed structure in conditions without continuous illumination for the flashed eye. It was concluded that a visual percept which enters the processor as non-EP-evoking information nevertheless is reflected by the EP waveform. However, the waveforms are different if the flashes carry the perceptual information exclusively. More powerful than visual structure is the mode of flash presentation (with or withoug continuous target illumination) for the EP waveform.
Adult↗
THE TIME-INTENSITY RELATION IN VISUAL PERCEPTION AS A FUNCTION OF OBSERVER'S TASK.
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Humans↗
Mechanisms and asymmetries in visual perception of simultaneity and temporal order.
Temporally overlapping, spatially separated visual stimuli were used for studying perception of simultaneity and temporal order. Pairs of flashes each of 100 ms duration were presented with stimulus onset asynchronies of 0, 30, 50, and 70 ms. Three spatial arrangements of flash presentation were tested: both flashes were presented foveally; one flash was presented foveally and the other at 8 deg in the left visual hemifield; one flash was presented foveally and the other at 8 deg in the right visual hemifield. Onset asynchronies of 30 and 50 ms were not sufficient for correct identification of temporal order although the flashes were not perceived as simultaneous. Analysis of the response distributions suggests the existence of two-independent mechanisms for evaluating temporal interrelations: one for detecting simultaneity and the other for identifying temporal order. A better detection of simultaneity was found when synchronous flashes were presented together with pairs of flashes separated by larger onset asynchronies. Reading habits may explain only part of the left-right asymmetries of the response distributions. The possible lateralization of the two suggested mechanisms within the cerebral hemispheres is discussed.
Adult↗
Behavioral evidence for visual perception of 3-dimensional surface structures in monkeys.
Human subjects perceive two crossing bars, one in front of the other, when shown a cross with disparity added to its horizontal limbs, and they also perceive neon-color spreading when shown a stereoscopic Redies-Spillmann figure. It has thus been hypothesized that the human visual system follows the principle of generic image sampling in reconstructing 3-dimensional (3-D) surface structures. Here we examine whether monkeys also perceive these surface structures. The results indicate that monkeys, like humans, perceive two crossing bars and neon-color spreading and suggest that the principle of generic image sampling may also be applied to visual perception in monkeys.
Animals↗
[Cognition for visual perception of a student apprentice of dental hygiene to the presence of a parent beside the dental chair for dental treatment. The study of cognitive style and personality traits].
With a view to knowing how the dental hygienist looks at and makes cognition of a mother who is kept standing by her child just receiving his dental treatment, cognition from visual perception was examined, by dental hygienist apprentice. Possible difference in scene cognition process according to different cognition style of these subjects was also analyzed from the elements of eye-movement. On the basis of the results of a YG character test performed together, cognition styles and personality traits were examined additionally. The results obtained were as follows: 1. From the number of total scanned sites upon the observation of test movie, 9 and 6 subjects having reflective cognition style and impulsive cognition style, respectively could be divided out of all 43 subjects. 2. When the mother's countenance turned from calmness to uneasiness, the reflective style-group showed increased gaze at the mother's face. 3. When the mother's countenance turned from calmness to uneasiness, the impulsive style-group showed especially increased gaze at the child's face, with a tendency to gazing obviously biased toward his face. 4. The reflective style-group tended to have visual scanning strategies by which it observes each of the sites under test movie, while always contrasting them. 5. The impulsive style-group tended to have visual scanning strategies by which it observes one of the sites under test movie and then the other. 6. Compared with the reflective style-group, the impulsive style-group showed personality traits such as less depression, low general activity and weak initiative. 7. The above results revealed that a subject having impulsive cognition style found a difficulty in taking a wide view of the situation in which its mother is just present in the treating room and was easily put under visual influence of any change in its mother's countenance.
Adult↗
Cognitive evoked potentials related to visual perception of motion in human subjects.
A method was tested for simultaneous recordings of evoked potentials from the secondary visual cortex (mediotemporal) and from the brain cognitive areas (fronto-central). Visual moving stimulations with cognitive tasks seem to be suitable for combined examination of visual motion perception and cognitive processes based on the magnocellular system activity. This arrangement enhances the analysis of visual information processing and evaluation of central nervous system functions.
Adult↗
VARIANCE COMPONENTS IN THE DEVELOPMENTAL TEST OF VISUAL PERCEPTION.
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Child↗
The influence of a stationary single line in darkness on the visual perception of eye level.
The angle of pitch of a visual field consisting of only a single vertical, 64 degrees-long, eccentrically-located line in otherwise total darkness influences the elevation of a target set to appear at eye level (VPEL). The influence changes linearly with the magnitude of pitch over the range from -30 degrees to +20 degrees. The average slope of the VPEL-vs-pitch function is +0.53. The influence on VPEL of a pitched visual field consisting of two parallel vertical lines is slightly greater (slope = +0.56), and the influence of the pitch of a complexly-structured well-illuminated pitched room is slightly greater yet (slope = +0.63). The pitch of a frontoparallel plane containing one horizontal line has a small influence on VPEL (slope = +0.08); the influence with two horizontal lines is slightly greater (slope = +0.18). The slope of the VPEL-vs-pitch function differs among individual subjects but is linear for each of the eight subjects. A great deal of consistency is manifested by individual subjects across all of the visual fields: an individual with a steep slope with one visual field tends to have a steep slope with all visual fields. The individual's characteristic response in total darkness is strongly correlated with the response to an erect well-illuminated visual field. The significant aspect of the pitched-from-vertical line stimulus is the change in orientation of its retinal image. An additional experiment with a small pupil (pilocarpine) indicates that cues related to other retinal gradients or to accommodation play no role in the influence of the visual field on VPEL. The experiments provide support for treating the visual influence on VPEL by means of the Great Circle Model.
Convergence, Ocular↗
Spatio-temporal disintegration of visual perception in schizophrenia as revealed by a novel cognitive task, the Searchlight Test.
We developed a novel computer-assisted psychological test (the Searchlight Test) in order to explore 'cognitive fragmentation' and its relation to thought disorder in schizophrenic patients. Participants were instructed to search geometric figures through a small hole (3 cm in diameter) on a display monitor by moving a mouse device and to reconstruct an image of the whole from the temporally and spatially fragmented visual stimuli.The cognitive function measures in 24 schizophrenic patients and 14 normal controls showed that the error rates of the recall task (drawing the figure from memory) and the recognition task (selecting the correct figure from several similar figures) were significantly higher in schizophrenic patients than in normal controls. The error rates of both tasks significantly correlated with disorganization syndrome in schizophrenia, but not with reality distortion or with psychomotor poverty syndrome.The present data obtained with the Searchlight Test suggest the spatio-temporal disintegration of visual perception in schizophrenia and its correlation with disorganization. This test appears to provide a useful tool for studying the pathophysiology of disorganization syndrome, thought disorder and the related cognitive dysfunction of schizophrenia.
Adult↗
Auditory, visual, and auditory-visual perception of vowels by hearing-impaired children.
The vowels (foreign letters in text) were presented through auditory, visual, and combined auditory-visual modalities to hearing-impaired children having good, intermediate, and poor auditory work-recognition skills. When they received acoustic information only, children with good word-recognition skills confused neighboring vowels (i.e., those having similar formant frequencies). Children with intermediate work-recognition skills demonstrated this same difficulty and confused front and back vowels. Children with poor word-recognition skills identified vowels mainly on the basis of temporal and intensity cues. Through lipreading alone, all three groups distinguished spread from rounded vowels but could not reliably identify vowels within the categories. The first two groups exhibited only moderate difficulty in identifying vowels audiovisually. The third group, although showing a small amount of improvement over lipreading alone, still experienced difficulty in identifying vowels through combined auditory and visual modes.
Adolescent↗
Op art and visual perception.
An attempt is made to list the visual phenomena exploited in op art. These include moire frinlude moiré fringes, afterimages, Hermann grid effects, Gestalt grouping principles, blurring and movement due to astigmatic fluctuations in accommodation, scintillation and streaming possibly due to eye movements, and visual persistence. The historical origins of these phenomena are also noted.
Afterimage↗