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.

Left—Right Visual Field Asymmetry in Bistable Motion Perception

Perception ◽  
1988 ◽  
Vol 17 (6) ◽  
pp. 721-727 ◽  
Author(s):  
Clara Casco ◽  
Donatella Spinelli
Keyword(s):  
Visual Field ◽  
Visual Fields ◽  
Stimulus Presentation ◽  
The Other ◽  
Right Visual Field ◽  
The Third ◽  
Group Movement ◽  
Left Handed ◽  
Left And Right ◽  
Left Right Asymmetry

Twelve observers viewed two alternating frames, each consisting of three rectangular bars which were displaced laterally by one cycle in one frame with respect to the other. At long interframe intervals (IFIs) observers perceived a group of three elements moving as a whole (group movement), whereas with IFIs shorter than 40–60 ms the overlapping elements in each frame appeared stationary while the third element appeared to move from one end of the display to the other (end-to-end movement). The percentage of group movement responses in central viewing was compared to those obtained for stimulus presentation in the left and right visual fields (4 deg eccentricity), for opposite horizontal directions of motion. All ten right-handed subjects showed a left-field advantage in sensitivity to group movement. The two left-handed subjects showed a similar advantage in sensitivity with right-field presentation. The effects of monocular vision, hand used in the task, spatial frequency, and contrast on visual field asymmetry were all investigated in two right-handed subjects. None of these factors affected the left—right asymmetry.

The interpretation of results of 10-2 visual fields should consider individual variability in the position of the optic disc and temporal raphe

2017 ◽  
Vol 102 (3) ◽  
pp. 323-328 ◽  
Author(s):  
Fumi Tanabe ◽  
Chota Matsumoto ◽  
Allison M McKendrick ◽  
Sachiko Okuyama ◽  
Shigeki Hashimoto ◽  
...  
Keyword(s):  
Visual Field ◽  
Optic Disc ◽  
Test Pattern ◽  
Visual Fields ◽  
Individual Variability ◽  
Structure And Function ◽  
En Face ◽  
Test Points ◽  
And Function ◽  
Oct Image

AimsTo clarify the anatomical relation between the optic disc and temporal raphe and to examine how these are related to test points in the 10-2 visual field test pattern.Subjects and methodsFor 22 eyes of volunteers with normal vision (+0.75 D spherical equivalent 7.88 D), a volume scan was used to obtain en-face images from a plane fitted to the inner limiting membrane using optical coherence tomography (OCT). The clearest en-face retinal nerve fibre (RNF) image was chosen for each subject and superimposed on fundus photographs using blood vessels for alignment. Individual landmarks (disc, fovea and visual field blind spot) were then used to superimpose the Humphrey Field Analyzer 10-2 visual field on the OCT image to compare with the RNF image.ResultsThe average disc–fovea–raphe angle was 169.4°±3.2°. Both the disc and temporal raphe were located above the horizontal midline (ie, were inferior in visual field space). For the 10-2 test pattern superimposed on the OCT image, in 54.5% of eyes, the temporal inferior test points adjacent to the horizontal midline mapped to the anatomical inferior hemifield. In 22.7% of eyes, nasal inferior test points adjacent to the horizontal midline mapped to the anatomical inferior hemifield. This mapping is opposite to typically assumed.ConclusionThe position of the disc and raphe affects the mapping between structure and function with respect to superior and inferior hemifields. Individual differences in the position of the temporal raphe should be considered when mapping between structure and function for the 10-2 test pattern.

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.

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.

Orienting Attention across the Vertical Meridian: Evidence from Callosotomy Patients

1990 ◽  
Vol 2 (3) ◽  
pp. 232-238 ◽  
Author(s):  
P. A. Reuter-Lorenz ◽  
R. Fendrich
Keyword(s):  
Visual Field ◽  
Corpus Callosum ◽  
Visual Fields ◽  
Posterior Region ◽  
Interhemispheric Communication ◽  
Vertical Meridian ◽  
Left And Right

This study investigates whether interhemispheric interactions mediated by the corpus callosum play a role in orienting attention across the vertical meridian. Patients with complete or partial section of the corpus callosum participated in a spatial precueing task under conditions that required covert shifts of attention within or between the visual fields. Patients with complete callosal section demonstrated normal costs on invalid trials when the cue and target appeared in the same visual field. However, these patients were impaired on invalid trials in which attention had to be redirected across the vertical meridian. The between–within difference emerged only for patients with complete callosal section; it was not evident for a patient with section restricted to the anterior two-thirds of the callosum. Control experiments demonstrated that the deficit (1) is specific to shifts across the vertical meridian, (2) is not due to shifting between left and right hemispace, and (3) is related to the voluntary allocation of attention in response to the cue. These results suggest that interhemispheric communication, which is normally mediated by the posterior region of the corpus callosum, contributes to the efficient movement of attention between visual fields.

Visual Field-Cerebral Hemisphere Differences in Perception of Visual Nonverbal Stimuli

1979 ◽  
Vol 48 (3_suppl) ◽  
pp. 1127-1131 ◽  
Author(s):  
Alice A. Kemp ◽  
Richard H. Haude
Keyword(s):  
Visual Field ◽  
Visual Recognition ◽  
Visual Fields ◽  
Recognition Task ◽  
Manual Responses ◽  
Low Threshold ◽  
Left And Right ◽  
Level Performance ◽  
Threshold Duration ◽  
Minimal Intensity

16 subjects were tested for differences between left and right visual fields in accuracy of recognition for paired verbal and nonverbal stimuli presented at below threshold duration and at minimal intensity. Performance on the visual recognition task was also compared with scores on a written n-Ach test. The data clearly indicated superior recognition of physiognomic stimuli presented in the left visual field and above-chance-level performance of subjects' manual responses for these be low-threshold stimuli. The data also hint at a possible relationship between n-Ach and accuracy of visual recognition in the left hemisphere.

Some Effects of Advanced Aging on the Visual-Language Processing Capacity of the Left and Right Hemispheres

1990 ◽  
Vol 33 (1) ◽  
pp. 134-140 ◽  
Author(s):  
Michael P. Rastatter ◽  
Richard A. McGuire
Keyword(s):  
Visual Field ◽  
Language Processing ◽  
False Positive ◽  
False Negative ◽  
Visual Fields ◽  
Reaction Times ◽  
Elderly Subjects ◽  
Time Data ◽  
Error Type ◽  
Left And Right

The present study investigated the effects of advanced aging on hemispheric organization for visual-linguistic processing. Lexical decision vocal-reaction times of geriatric subjects were measured for unilaterally presented concrete and abstract nouns in an attempt to obtain an index of differential left and right hemispheric processing ability. Results of an ANOVA procedure showed that reaction times were significantly faster when subjects were presented the stimulus items in their right visual fields, regardless of whether the item was a concrete or abstract word. An ANOVA procedure applied to the arcsine of the percentages of occurrence of false-positive and false-negative error types showed a significant interaction between the error type and visual field variables. Post hoc tests showed left visual field, false-positive errors occurred significantly more often than the remaining visual field, error type configurations. Finally, for the reaction time data, a significant correlation existed between the two visual fields for the concrete and abstract items. Collectively, such findings were consistent with a callosal relay model of neurolinguistic organization, suggesting that the right hemisphere’s ability to perform lexical decisions was diminished in the present group of elderly subjects.

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.

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