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.

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.

Electroencephalographic Activity in a Flanker Interference Task Using Japanese Orthography

2002 ◽  
Vol 14 (7) ◽  
pp. 971-979 ◽  
Author(s):  
Shuhei Yamaguchi ◽  
Genya Toyoda ◽  
Jiang Xu ◽  
Shotai Kobayashi ◽  
Avishai Henik
Keyword(s):  
Visual Field ◽  
Left Visual Field ◽  
Right Hemisphere ◽  
Hemispheric Specialization ◽  
Late Phase ◽  
Right Visual Field ◽  
Interference Effects ◽  
Interference Task ◽  
Dorsolateral Prefrontal ◽  
The Right

The neural activities for color word interference effects were investigated using event-related brain potentials (ERPs) recorded in a flanker-type interference task. Kanji words (Japanese morphograms) and kana words (Japanese phono-grams) were used as the flanker stimuli to obtain insights about hemispheric specialization for processing two types of Japanese orthographies. Interference effects in reaction time were larger when kanji words were presented in the left visual field and when kana words were in the right visual field. ERPs were modulated by the incongruent flankers, which generated a negative ERP component with the different onset and offset depending on flanker attributes. Consistent with the behavioral data, the interference-related negativity was observed for kanji words presented in the left visual field and for kana words in the right visual field. The negativity distributed maximally over the fronto-central site. The early part of the negativity distributed strongly over the frontal midline area, whereas it extended bilaterally over the frontal area in the late phase. The present results support the view of preferential processing of kanji in the right hemisphere and that of kana in the left hemisphere. The temporal profile of scalp topographies for the interference-related neural activity suggests that the medial and dorsolateral prefrontal regions may be involved in maintaining attentional set and conflict resolution.

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.

Sex hormonal modulation of hemispheric asymmetries in the attentional blink

2005 ◽  
Vol 11 (3) ◽  
pp. 263-272 ◽  
Author(s):  
ANTJE HOLLÄNDER ◽  
MARKUS HAUSMANN ◽  
JEFF P. HAMM ◽  
MICHAEL C. CORBALLIS
Keyword(s):  
Visual Field ◽  
Attentional Blink ◽  
Right Hemisphere ◽  
Visual Presentation ◽  
Right Visual Field ◽  
Probe Item ◽  
Cerebral Asymmetries ◽  
Hormonal Modulation ◽  
The Right ◽  
Midluteal Phase

The present study examines differences in functional cerebral asymmetries modulated by gonadal steroid hormones during the menstrual cycle in women. Twenty-one right-handed women with regular menstrual cycles performed a double-stream rapid serial visual presentation (RSVP) task, with one stream in each visual field, during the low steroid menses and the high steroid midluteal phase. They were required to detect a target item, and then a probe item, each of which could appear in either stream. If the probe item appeared 200 ms after the target, detection of the probe was impaired—a phenomenon known as the “attentional blink.” This occurred in both streams in the midluteal phase, but only in the right visual field during menses. Thus low steroid levels appeared to restrict the attentional blink to the left hemisphere, while high levels of estradiol and progesterone in the midluteal phase appeared to reduce functional asymmetries by selectively increasing the attentional blink in the right hemisphere. This effect appears to be mediated by estradiol rather than progesterone, and it is compatible with the assumption of a hormone-related suppression of right hemisphere functions during the midluteal phase. (JINS, 2005,11, 263–272.)

Locus of information in words and the right visual field effect

1990 ◽  
Vol 14 (1) ◽  
pp. 44-58 ◽  
Author(s):  
M.P Bryden ◽  
T.Alexandre Mondor ◽  
Martin Loken ◽  
Margaret A Ingleton ◽  
Kathy Bergstrom
Keyword(s):  
Visual Field ◽  
Field Effect ◽  
Right Visual Field ◽  
Visual Field Effect ◽  
The Right

Left-Right Differences in Tachistoscopic Recognition: Directional Scanning or Cerebral Dominance?

1966 ◽  
Vol 23 (3_suppl) ◽  
pp. 1127-1134 ◽  
Author(s):  
M. P. Bryden
Keyword(s):  
Visual Field ◽  
Cerebral Dominance ◽  
Mirror Image ◽  
Single Letter ◽  
Hemispheric Dominance ◽  
Right Visual Field ◽  
Tachistoscopic Recognition ◽  
The Right ◽  
Image Orientation ◽  
Visual Field Superiority

Although both single letters and groups of 3 letters are more readily identified when they appear in the right visual field, right visual-field superiority on the 2 tasks is not correlated. Single letters presented in mirror-image orientation are also better identified in the right visual field. These results suggest that hemispheric dominance is more important than directional scanning in determining left-right differences in the recognition of single-letter material.

scholarly journals Lateralization of attention in adults with ADHD: Evidence of pseudoneglect

2020 ◽  
Vol 63 (1) ◽  
Author(s):  
Bartosz Helfer ◽  
Stefanos Maltezos ◽  
Elizabeth Liddle ◽  
Jonna Kuntsi ◽  
Philip Asherson
Keyword(s):  
Reaction Time ◽  
Visual Field ◽  
Reaction Times ◽  
Study Participant ◽  
Reaction Time Task ◽  
Right Visual Field ◽  
Time Variability ◽  
Incentive Condition ◽  
Reaction Time Variability ◽  
The Right

Abstract Background. We investigated whether adults with attention-deficit/hyperactivity disorder (ADHD) show pseudoneglect—preferential allocation of attention to the left visual field (LVF) and a resulting slowing of mean reaction times (MRTs) in the right visual field (RVF), characteristic of neurotypical (NT) individuals —and whether lateralization of attention is modulated by presentation speed and incentives. Method. Fast Task, a four-choice reaction-time task where stimuli were presented in LVF or RVF, was used to investigate differences in MRT and reaction time variability (RTV) in adults with ADHD (n = 43) and NT adults (n = 46) between a slow/no-incentive and fast/incentive condition. In the lateralization analyses, pseudoneglect was assessed based on MRT, which was calculated separately for the LVF and RVF for each condition and each study participant. Results. Adults with ADHD had overall slower MRT and increased RTV relative to NT. MRT and RTV improved under the fast/incentive condition. Both groups showed RVF-slowing with no between-group or between-conditions differences in RVF-slowing. Conclusion. Adults with ADHD exhibited pseudoneglect, a NT pattern of lateralization of attention, which was not attenuated by presentation speed and incentives.

Hemispheric Specialization for Processing Chinese Characters: Some Evidence from Lexical Decision Vocal Reaction Times

1989 ◽  
Vol 69 (3_suppl) ◽  
pp. 1083-1089 ◽  
Author(s):  
Michael P. Rastatter ◽  
Gail Scukanec ◽  
Jeff Grilliot
Keyword(s):  
Visual Field ◽  
Lexical Decision ◽  
Hemispheric Specialization ◽  
Visual Fields ◽  
Reaction Times ◽  
Decision Processes ◽  
Right Visual Field ◽  
Chinese Characters ◽  
Error Type ◽  
Chinese Subjects

Lexical decision vocal reaction times (RT) were obtained for a group of Chinese subjects to unilateral tachistoscopically presented pictorial, single, and combination Chinese characters. The RT showed a significant right visual-field advantage, with significant correlations of performance between the visual fields for each type of character. Error analysis gave a significant interaction between visual fields and error type—significantly more false positive errors occurred following left visual-field inputs. These results suggest that the left hemisphere was responsible for processing each type of character, possibly reflecting superior postaccess lexical-decision processes.

On the Relation between Visual Spatial Attention and Visual Field Asymmetries

1992 ◽  
Vol 44 (3) ◽  
pp. 529-555 ◽  
Author(s):  
T. A Mondor ◽  
M.P. Bryden
Keyword(s):  
Visual Field ◽  
Visual Attention ◽  
Visual Fields ◽  
Stimulus Onset ◽  
Right Visual Field ◽  
Structural Factors ◽  
Letter Identification ◽  
Functional Capabilities ◽  
Visual Spatial ◽  
The Right

In the typical visual laterality experiment, words and letters are more rapidly and accurately identified in the right visual field than in the left. However, while such studies usually control fixation, the deployment of visual attention is rarely restricted. The present studies investigated the influence of visual attention on the visual field asymmetries normally observed in single-letter identification and lexical decision tasks. Attention was controlled using a peripheral cue that provided advance knowledge of the location of the forthcoming stimulus. The time period between the onset of the cue and the onset of the stimulus (Stimulus Onset Asynchrony—SOA) was varied, such that the time available for attention to focus upon the location was controlled. At short SO As a right visual field advantage for identifying single letters and for making lexical decisions was apparent. However, at longer SOAs letters and words presented in the two visual fields were identified equally well. It is concluded that visual field advantages arise from an interaction of attentional and structural factors and that the attentional component in visual field asymmetries must be controlled in order to approximate more closely a true assessment of the relative functional capabilities of the right and left cerebral hemispheres.

scholarly journals Chronic (Rasmussen’s) Encephalitis in an Adult

2003 ◽  
Vol 30 (3) ◽  
pp. 263-265 ◽  
Author(s):  
Richard Wennberg ◽  
Sukriti Nag ◽  
Mary-Pat McAndrews ◽  
Andres M. Lozano ◽  
Richard Farb ◽  
...  
Keyword(s):  
Visual Field ◽  
Right Visual Field ◽  
Loss Of Consciousness ◽  
Mild Head Injury ◽  
Partial Seizures ◽  
Complex Partial Seizures ◽  
The Past ◽  
Rasmussen’S Encephalitis ◽  
The Face ◽  
The Right

A 24-year-old woman was referred because of incompletely-controlled complex partial seizures. Her seizures had started at age 21, after a mild head injury with brief loss of consciousness incurred in a biking accident, and were characterized by a sensation of bright flashing lights in the right visual field, followed by numbness and tingling in the right foot, spreading up the leg and to the arm, ultimately involving the entire right side, including the face. Occasionally they spread further to involve right facial twitching with jerking of the right arm and leg, loss of awareness and, at the onset of her epilepsy, rare secondarily generalized convulsions. Seizure frequency averaged three to four per month. She was initially treated with phenytoin and clobazam and subsequently changed to carbamazepine 800 milligrams per day. She also complained that her right side was no longer as strong as her left and that it was also numb, especially the leg, but felt that this weakness had stabilized or improved slightly over the past two years.

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