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.

Categorical and Metric Spatial Processes Distinguished by Task Demands and Practice

1999 ◽  
Vol 11 (2) ◽  
pp. 153-166 ◽  
Author(s):  
Marie T. Banich ◽  
Kara D. Federmeier
Keyword(s):  
Visual Field ◽  
Right Hemisphere ◽  
Receptive Fields ◽  
Spatial Relations ◽  
Task Demands ◽  
Spatial Processing ◽  
Right Visual Field ◽  
Metric Distance ◽  
The Right ◽  
Categorical Spatial Relations

In this study we examined Kosslyn's (1987) claim that the right hemisphere exhibits a relative superiority for processing metric spatial relations, whereas the left hemisphere exhibits a relative superiority for processing categorical spatial relations. In particular, we examined whether some failures to observe strong visual field (VF) advantages in previous studies might be due to practice effects that allowed individuals to process tasks in alternative manners (e.g., to process a metric task using a categorical strategy). We used two versions of a task previously employed by Hellige and Michimata (1989) in which individuals judge the metric (distance) or categorical (above/below) spatial relations between a bar and a dot. In one version, the position of the bar was held static. In another, the bar's position varied. This manipulation prevented participants from using the computer screen as a reference frame, forcing them to compute the spatial relationships on the basis of the relevant items only (i.e., the bar and the dot). In the latter, but not the former version of the task we obtained evidence supporting Kosslyn's hypothesis, namely, a significant right visual field (RVF) advantage for categorical spatial processing and a trend toward a left visual field (LVF) advantage for metric spatial processing. Furthermore, the pattern of results for trials on which information was presented centrally (CVF trials) was similar to that observed on RVF trials, whereas the pattern for trials in which identical information was presented in each visual field (BVF trials) was similar to that observed on LVF trials. Such a pattern is consistent with Kosslyn's suggestion that categorical processing is better suited for cells with small receptive fields and metric processing for cells with larger receptive fields.

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.

Lateralization of defence mechanisms: Differing influences on perception with left and right visual field presentation of anxiety‐arousing stimulation

1989 ◽  
Vol 3 (3) ◽  
pp. 167-179 ◽  
Author(s):  
Ingegerd Carlsson
Keyword(s):  
Visual Field ◽  
Undergraduate Students ◽  
Right Hemisphere ◽  
Right Visual Field ◽  
Defence Mechanisms ◽  
Psychoanalytic Literature ◽  
Contrast Technique ◽  
Left And Right ◽  
The Right ◽  
Perceptual Styles

Forty‐five undergraduate students were randomly divided into two groups and tested with the Meta‐Contrast Technique (MCT), in the left or right visual field (VF). In the MCT, the presentation of a subliminal threatening picture is intended to evoke anxiety and ego mechanisms of defence against it. More signs of repressive plus isolating defences were found in the left hemisphere (LH) group. Signs of projection plus regression tended to be more common in the right hemisphere (RH) group. The total number of anxiety signs in the MCT protocols did not differ between the groups. A clear sex difference was noticed, namely that the female LH and RH groups showed significant lateralization, while the male groups did not differ significantly on a combined defensive score. The data suggest that the left and right hemispheres may show differing perceptual styles, which are described as ego mechanisms of defence in the psychoanalytic literature.

Cerebral Asymmetries in Random-Dot Stereopsis: Reversal of Direction with Changes in Dot Size

Perception ◽  
1979 ◽  
Vol 8 (6) ◽  
pp. 683-690 ◽  
Author(s):  
Colin B Pitblado
Keyword(s):  
Visual Field ◽  
Hemispheric Specialization ◽  
Right Visual Field ◽  
Cerebral Asymmetries ◽  
Form Recognition ◽  
Random Dot Stereograms ◽  
Visual Field Effect ◽  
Per Se ◽  
The Right ◽  
Visual Field Superiority

Visual field differences in stereoscopic form recognition using Julesz-type random dot stereograms were investigated. Dot size was varied in order to test the possibility that variations in the carrier dimension have contributed to past estimates of visual field differences. Twelve male and twelve female subjects, all right-handed, appeared for three test sessions—one with each different dot size. In each session the stimuli were flashed twenty-four times in each visual field, for 120 ms. Results showed no overall visual field effect, but a highly significant interaction between visual field and dot size. For small dots, left visual field superiority was observed, as previously reported by Durnford and Kimura. With large dots, however, the right visual field was superior. This reversal of visual field differences as a function of dot size implies that there is no consistent cerebral hemispheric specialization for stereopsis or stereoscopic form recognition per se. Instead, it appears that there is relative hemispheric specialization for responding to the carrier of stereoscopic information.

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.

Object-Centered Attentional Biases in the Intact Brain

1996 ◽  
Vol 8 (6) ◽  
pp. 540-550 ◽  
Author(s):  
Patricia A. Reuter-Lorenz ◽  
Maxwell Drain ◽  
Corinne Hardy-Morais
Keyword(s):  
Visual Field ◽  
Right Visual Field ◽  
Normal Brain ◽  
Opposite Pattern ◽  
Intact Brain ◽  
Left And Right ◽  
The Right ◽  
Neurologically Intact ◽  
Patient Studies ◽  
Better Than

By simulating neglect-like effects in neurologically intact observers, we evaluated whether normal attentional allocation can be object centered. In a series of three experiments, observers detected a small gap on the left or right side of a configuration presented in either the left of right visual field. The figures were positioned so that on different trials, the left and right sides would fall in the same retinotopic, hemispatial, and environmental location. Thus, only the location with respect to an object-centered frame varied. We found opposite patterns of bias within each visual field: For figures in the left visual field, left gaps were detected better than right gaps, whereas in the right visual field the opposite pattern was evident. Control conditions indicate that these biases are not due to masking from eccentric contours and depend on the left and right segments being united into a single form. These results indicate that opposing orientational biases of the left and right hemispheres can operate within an object-centered frame in the normal brain. This evidence converges with patient studies and single-unit electrophysiology to reveal the importance of a relatively late, abstract locus for visual selection.

Cerebral Asymmetry in Facial Affect Perception by Women: Neuropsychological Effects of Depressed Mood

1994 ◽  
Vol 79 (3_suppl) ◽  
pp. 1667-1679 ◽  
Author(s):  
W. David Crews ◽  
David W. Harrison
Keyword(s):  
Visual Field ◽  
Depressed Mood ◽  
Reaction Times ◽  
Right Visual Field ◽  
Hemispheric Processing ◽  
Neuropsychological Effects ◽  
Arousal Theory ◽  
Left And Right ◽  
State And Trait Anxiety ◽  
The Right

40 right-handed women, half of whom had been classified with depressed mood and the other half as nondepressed, participated in a tachistoscopic study of the influence of depressed mood on the cerebral hemispheric processing of Ekman and Friesen's 1976 happy, sad, and neutral emotional faces using a forced-choice reaction-time paradigm with only happy and sad alternatives as response manipulanda. The women with depressed mood were also characterized by elevated scores on both state and trait anxiety, suggestive of an anxious-depressive state with heightened arousal. Primary findings for the tachistoscopic data indicated that women with depressed mood as compared to nondepressed women displayed significantly faster reaction times to sad faces presented in the right visual field and happy faces presented in the left visual field. These results are suggestive of differential arousal of both the left and right cerebral hemispheres in this sample of anxious-depressed women and are discussed in light of arousal theory.

Spatio-Temporal Discrimination of Frequency in the Right and Left Visual Fields: A Preliminary Report

1981 ◽  
Vol 53 (1) ◽  
pp. 311-316 ◽  
Author(s):  
Stephen M. Rao ◽  
Daniel Rourke ◽  
R. Douglas Whitman
Keyword(s):  
Visual Field ◽  
Visual Processing ◽  
Visual Information ◽  
Temporal Discrimination ◽  
Visual Fields ◽  
Temporal Variations ◽  
Right Visual Field ◽  
Spatial Frequencies ◽  
Left And Right ◽  
The Right

Normal right-handed subjects were presented with luminance patterns varying sinusoidally in both space and time to the left and right visual fields. With no temporal variation in the stimuli, detection thresholds for the left visual field were lower than those for the right visual field for all spatial frequencies. However, with increasing temporal variations, a reversal in detection of threshold occurred, with the right visual field surpassing the left. This finding suggests that left and right visual processing may be differentially efficient for temporal and spatial visual information.

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