Duration of the Motion Aftereffect as a Function of Retinal Locus and Visual Field

1979 ◽  
Vol 48 (1) ◽  
pp. 143-146 ◽  
Author(s):  
Alan A. Beaton
Keyword(s):  
Visual Field ◽  
Motion Aftereffect ◽  
Cerebral Hemispheres ◽  
New Method ◽  
Retinal Locus ◽  
Rotating Disc ◽  
Left And Right ◽  
Method Of Measurement ◽  
The Right

The duration of the aftereffect induced by viewing a rotating disc was recorded separately for the four hemiretinae of the left and right eyes using a new method of measurement. The results showed duration of aftereffect to differ between nasal and temporal hemiretinae of the right eye and between left and right cerebral hemispheres.

scholarly journals Visual Pattern Recognition in the Cerebral Hemispheres: The Role of Spatial Filtering

1982 ◽  
Vol 55 (3_suppl) ◽  
pp. 1319-1326 ◽  
Author(s):  
Fred H. Previc
Keyword(s):  
Pattern Recognition ◽  
Visual Field ◽  
High Frequency ◽  
Spatial Filtering ◽  
Cerebral Hemispheres ◽  
Visual Pattern ◽  
Right Visual Field ◽  
Visual Pattern Recognition ◽  
Left And Right ◽  
The Right

The differences between the left and right cerebral hemispheres in terms of visual pattern recognition were examined within the context of the spatial filtering model of visual perception. On the basis of a wide range of evidence, it was hypothesized that the right hemisphere's predominant role in Gestalt perception may be related to its superiority in processing low spatial frequency information, while the left hemisphere may be more highly involved in an analysis of high frequency information contained in the visual environment. The spatial filtering capabilities of the left and right hemispheres were assessed by presenting square-wave gratings to the left and right visual fields, which project to the primary visual cortical areas of the contralateral hemispheres. 24 right-handed adult males were required to identify the orientation of each of six gratings varying in fundamental spatial frequency and level of contrast. Analyses of variance indicated that identification performance was superior over-all in the right visual field. The magnitude of the advantage of the right visual field latency was greater for the high frequency gratings, although this predicted trend did not attain significance. Results were discussed in relation to the spatial filtering theory and others concerning hemispheric differences in visual pattern recognition.

Left and Right Visual Field Superiority for Letter Classification

1979 ◽  
Vol 31 (3) ◽  
pp. 423-439 ◽  
Author(s):  
John Jonides
Keyword(s):  
Visual Field ◽  
Task Demands ◽  
Perceptual Processing ◽  
Right Visual Field ◽  
Left And Right ◽  
The Right ◽  
Visual Field Superiority

Two letter classification experiments examine the hypothesis that lateral asymmetries in perceptual processing are sensitive to subtle changes in task demands. The first experiment reports a right visual field superiority for an easy letter classification, but a left field superiority for a difficult classification using the same population of stimuli. Experiment II demonstrates that the right field superiority can be reversed if the easy classification trials are embedded among more difficult trials. The implications of these results for theories of hemispheric localization are discussed.

Cerebral Lateralization of Global-Local Processing in Left- and Right-Handed People

2005 ◽  
Vol 100 (3) ◽  
pp. 734-742 ◽  
Author(s):  
Mohammad Ali Goodarzi ◽  
Mohammad Reza Taghavi ◽  
Mohammad Reza Zoughi
Keyword(s):  
Visual Field ◽  
Left Visual Field ◽  
Right Hemisphere ◽  
Local Processing ◽  
Cerebral Lateralization ◽  
Left Handed ◽  
Left And Right ◽  
The Right ◽  
Paradigm Analysis ◽  
Local Superiority

Cerebral lateralization of global-local processing of 70 left-handed and 70 right-handed students was compared using a computerized global-local task in a half-visual field paradigm. Analysis showed that left-handed individuals were slower than right-handed individuals in processing Globally Directed stimuli presented to the left visual field (right hemisphere). In addition, left-handed individuals showed smaller local superiority in the left hemisphere to the right-handed individuals. These findings are more consistent with Levy's prediction of spatial inferiority of left-handed individuals than Geschwind and Galaburda's or Annett's hypotheses.

Concept and Verbal Ability as Related to the Cerebral Hemispheres

1977 ◽  
Vol 45 (2) ◽  
pp. 555-566 ◽  
Author(s):  
Norman D. Cook
Keyword(s):  
Right Hemisphere ◽  
Verbal Ability ◽  
Cerebral Hemispheres ◽  
Cooperative Interaction ◽  
Goal State ◽  
Error Detector ◽  
Left And Right ◽  
The Right ◽  
The Relationship ◽  
State Functions

A new theory of human brain function is outlined in terms of the cooperative interaction of the cerebral hemispheres. The well-established verbal, symbolic functions of the left hemisphere and the wholistic, spatial functions of the right hemisphere are seen as separate and independent manifestations of the normally integrated verbal-analytic (or “error detector”) and conceptual (or “goal state”) functions of the left and right, respectively. The relationship between the hemispheres is described in terms of the “goal-directed” system of cybernetics and then compared with related ideas previously presented by Dimond, Penfield, and Piaget.

Bias for the Left Visual Field in Rapid Serial Visual Presentation: Effects of Additional Salient Cues Suggest a Critical Role of Attention

2015 ◽  
Vol 27 (2) ◽  
pp. 266-279 ◽  
Author(s):  
Kamila Śmigasiewicz ◽  
Dariusz Asanowicz ◽  
Nicole Westphal ◽  
Rolf Verleger
Keyword(s):  
Visual Field ◽  
Left Visual Field ◽  
Right Hemisphere ◽  
Critical Role ◽  
Visual Presentation ◽  
The Other ◽  
Early Posterior Negativity ◽  
Left And Right ◽  
The Right

Everyday experience suggests that people are equally aware of stimuli in both hemifields. However, when two streams of stimuli are rapidly presented left and right, the second target (T2) is better identified in the left hemifield than in the right hemifield. This left visual field (LVF) advantage may result from differences between hemifields in attracting attention. Therefore, we introduced a visual cue shortly before T2 onset to draw attention to one stream. Thus, to identify T2, attention was correctly positioned with valid cues but had to be redirected to the other stream with invalid ones. If the LVF advantage is caused by differences between hemifields in attracting attention, invalid cues should increase, and valid cues should reduce the LVF advantage as compared with neutral cues. This prediction was confirmed. ERP analysis revealed that cues evoked an early posterior negativity, confirming that attention was attracted by the cue. This negativity was earlier with cues in the LVF, which suggests that responses to salient events are faster in the right hemisphere than in the left hemisphere. Valid cues speeded up, and invalid cues delayed T2-evoked N2pc; in addition, valid cues enlarged T2-evoked P3. After N2pc, right-side T2 evoked more sustained contralateral negativity than left T2, least long-lasting after valid cues. Difficulties in identifying invalidly cued right T2 were reflected in prematurely ending P3 waveforms. Overall, these data provide evidence that the LVF advantage is because of different abilities of the hemispheres in shifting attention to relevant events in their contralateral hemifield.

The Lateralizer: a tool for students to explore the divided brain

2012 ◽  
Vol 36 (3) ◽  
pp. 220-225 ◽  
Author(s):  
Benjamin A. Motz ◽  
Karin H. James ◽  
Thomas A. Busey
Keyword(s):  
Visual Field ◽  
Undergraduate Students ◽  
Visual Fields ◽  
Cerebral Hemispheres ◽  
Brain Anatomy ◽  
Skill Sets ◽  
Divided Visual Field ◽  
Field Technique ◽  
Left And Right ◽  
And Function

Despite a profusion of popular misinformation about the left brain and right brain, there are functional differences between the left and right cerebral hemispheres in humans. Evidence from split-brain patients, individuals with unilateral brain damage, and neuroimaging studies suggest that each hemisphere may be specialized for certain cognitive processes. One way to easily explore these hemispheric asymmetries is with the divided visual field technique, where visual stimuli are presented on either the left or right side of the visual field and task performance is compared between these two conditions; any behavioral differences between the left and right visual fields may be interpreted as evidence for functional asymmetries between the left and right cerebral hemispheres. We developed a simple software package that implements the divided visual field technique, called the Lateralizer, and introduced this experimental approach as a problem-based learning module in a lower-division research methods course. Second-year undergraduate students used the Lateralizer to experimentally challenge and explore theories of the differences between the left and right cerebral hemispheres. Measured learning outcomes after active exploration with the Lateralizer, including new knowledge of brain anatomy and connectivity, were on par with those observed in an upper-division lecture course. Moreover, the project added to the students' research skill sets and seemed to foster an appreciation of the link between brain anatomy and function.

Models of Response Time to Peripheral Stimuli

1974 ◽  
Vol 18 (5) ◽  
pp. 533-533
Author(s):  
D.S. Kochhar ◽  
T.M. Fraser
Keyword(s):  
Visual Field ◽  
Response Time ◽  
Visual Fields ◽  
Stimulus Location ◽  
Stimulus Size ◽  
Tracking Task ◽  
Right Visual Field ◽  
Simulated Driving ◽  
Left And Right ◽  
The Right

The variable contribution of peripherally presented stimuli in a A sensory motor task has been explored in terms of stimulus and environmental variables. A simulated driving task was chosen as being a representative compensatory tracking task. Empirical models have been developed using response surface methodology, statistical design and data collected on a simulator with a 240° wrap-around screen and projection systems very much like cinerama. In this research, seven factors were isolated for a study of their effects on detection latency to peripherally presented stimuli when the subject was ‘driving’. These factors were stimulus size (circular stimuli between 18′ and 60′), stimulus color (red, white and green), stimulus-background contrast (background luminance 1ft.L and stimulus luminance of 30, 60 and 90 ft.L), stimulus location along the horizontal (between ± 90°) and vertical meridians (between ± 26°), intensity of continuous white noise (between 52 and 100 dbA), and complexity of the continuous central tracking task measured in terms of the simulated driving speed. Three levels of each variable were selected in a 7 factor Box-Behnken design. Twenty undergraduates between the ages 19 and 26 participated in the experiment. It was found that, in this multivariable environment when all seven factors were simultaneously varied, the effects of noise, stimulus location in the visual field and stimulus size were the more important determinants of response latency. In addition, marked differences for the left and right visual fields were observed for the right-handed subject population. Four models have been developed: two for the left visual field, with and without the continuous central task (CCT), and two for the right visual field for the same conditions. The response was found to be of the form 1/Yr = f (xi); i= 1,2,… 7 for both the left and right visual fields in the presence of the CCT. In the absence of the CCT the model was of the form Yr = f (xr) for the left and 1/2 = f (xi) for the right visual field where Yr = response time in millisec. and Yr xi = variables in equations. Response curves have been presented to illustrate the variation of response time with each of the seven variables for regions where response time may be expected to be a minimum. The implications of these curves and the models on which they are based have been examined from the design point of view.

Depth perception and evoked brain activity: The influence of horizontal disparity and visual field location

1997 ◽  
Vol 14 (3) ◽  
pp. 527-532 ◽  
Author(s):  
Wolfgang Skrandies
Keyword(s):  
Visual Field ◽  
Visual Information ◽  
Evoked Potential ◽  
Brain Activity ◽  
Right Visual Field ◽  
Functional Difference ◽  
Horizontal Disparity ◽  
Random Dot Stereograms ◽  
Left And Right ◽  
The Right

AbstractThe perception of dynamic random-dot stereograms (RDS) depends on the physiological fusion of horizontally disparate binocular visual input. Thus, the use of RDS offers the possibility to study selectively cortical processing of visual information in man. We investigated the influence of horizontal disparity on the scalp topography of RDS evoked brain activity in 33 healthy subjects. Stereoscopic checkerboard patterns were presented in the center or lateralized in the left or right visual field with horizontal disparities changing at temporal frequencies of six or eight depth reversals/s using different disparity values ranging from 3.5 to 28 min of arc. In 11 subjects evoked potential fields were recorded from 16 electrodes, and 21 subjects participated in 30-channel recordings with electrodes located over the parietal and occipital brain areas. Stimulation frequency-related brain activity was obtained with all disparity values; however, with large or small disparities the potential field strength decreased significantly while largest responses were obtained with intermediate disparities. Significant differences were observed in RDS evoked brain activity when central and lateralized stimulus locations were compared. With lateral stimuli (extending from the fovea to 17.1-deg eccentricity) maximal amplitudes were obtained at larger disparities than with central stimuli. In addition there were pronounced differences between brain activity evoked with stimuli presented in the left or right visual field; however, there were very similar evoked potential signals recorded from electrodes located over the left and right hemispheres. Our findings indicate that the processing of disparity information with lateralized stimuli is different from the processing in the center of the visual field. In addition, lateralized stimulation yields a significant disparity tuning mainly with stereoscopic targets occurring to the right from the fixation point (but not with stimuli to the left) suggesting a functional difference between the visual half-fields.

Lateralized Visual-Field Inattention in Schizophrenia

1994 ◽  
Vol 79 (1) ◽  
pp. 699-702 ◽  
Author(s):  
Daniel S. Lobel ◽  
Rex M. Swanda ◽  
Miklos F. Losonczy
Keyword(s):  
Visual Field ◽  
Cerebral Hemisphere ◽  
Right Visual Field ◽  
Verbal Processing ◽  
Cognitive Research ◽  
Schizophrenic Patients ◽  
Hemispheric Functioning ◽  
Left And Right ◽  
Verbal Functioning ◽  
The Right

Numerous studies have shown impaired verbal functioning in schizophrenic patients as compared with normals. The verbal deficits are generally attributed to damage of the left cerebral hemisphere. This attribution is based on literature which suggests that verbal processing is primarily mediated by the left hemisphere in right-handed humans. This study explored left-hemispheric integrity directly by assessing sustained attention in both the left and right hemispheres of 40 schizophrenic patients with the Weintraub Cancellation Tasks. Patients made significantly more errors of omission on the right visual field than on the left. These results are consistent with cognitive research in schizophrenia by demonstrating selective left-hemispheric impairment relative to right-hemispheric functioning.

scholarly journals Post-stroke Visual Impairment Treated with Korean Medical Treatment: A Case Series

2021 ◽  
Vol 42 (5) ◽  
pp. 1035-1044
Author(s):  
Young-ung Lee ◽  
Geonhui Kang ◽  
Kwangho Kim ◽  
Cheol-hyun Kim ◽  
Sunny Kang ◽  
...  
Keyword(s):  
Visual Field ◽  
Herbal Medicine ◽  
Medical Treatment ◽  
Visual Impairment ◽  
Parietal Lobe ◽  
Posterior Cerebral Artery ◽  
Case Series ◽  
Left And Right ◽  
The Mean ◽  
The Right

Objective: This study investigated two cases of Korean medical treatment for visual field impairment after stroke: Case 1, a 56-year-old male with a posterior cerebral artery infarction and right homonymous hemianopsia, and Case 2, a 46-year-old male with an intracerebral hemorrhage in the left parietal lobe and right homonymous hemianopsia.Methods: Case 1 was treated with acupuncture, electroacupuncture, and herbal medicine (Mangeum-tang) for two months, and Case 2 was treated with acupuncture, electroacupuncture, and herbal medicine (Oryeong-san) for 40 days.Results: Following treatment, for Case 1, the Humphrey visual field test showed improvement. The visual field indexes (VFIs) for the left and right eyes improved from 44% to 55% and 49% to 64% respectively, and the mean deviations (MDs) for the left and right eyes improved from -21.11 dB to -19.91 dB and -17.45 dB to -13.89 dB, respectively. The mean visual sensitivities (MVSs) of the left and right eyes also improved from 8.67 dB to 11.33 dB and 1.67 dB to 9.67 dB, respectively, with no side effects. For Case 2, the VFI for the left eye improved from 36% to 64% and that for the right eye remained unchanged. The MDs for the left and right eyes also improved from -22.02 dB to -14.47dB and -22.11 dB to -21.34 dB, respectively, with no side effects.Conclusions: This study suggests that Korean medical treatment may improve visual impairment after stroke, but further research is needed.

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