Reaction time to hemiretinal stimulation.

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dc.contributor.authorMaddess, Ralph Johannesen_US
dc.date.accessioned2024-08-14T22:33:50Z
dc.date.available2024-08-14T22:33:50Z
dc.date.copyright1972en_US
dc.date.issued1972
dc.degree.departmentDepartment of Psychology
dc.degree.levelMaster of Science M.Sc.en
dc.description.abstractFor a number of years investigators have been searching for tech­niques of use in researching brain function in normal subjects as well as benign methods of detecting brain lesions in subjects who have possible brain damage. Dichotic listening is one such technique. Now that relationships have been demonstrated between the differential ear effect found in dichotic listening and functional anomalies formerly reported in a number of brain damaged patients further efforts have been directed to refining this technique as a method of discovering brain damage and determining undiscovered aspects of brain function in normal subjects. However, even before this correspondence could be made it was necessary to show that the contralateral auditory fibers "dominate" the auditory system. This was accomplished by drawing inferences from animal and human neurophysiological and antomical research and by conducting further in­vestigations in this area. The impetus for the study contained herein comes from the idea that tachistoscopic research provides another area useful in the study of brain-function relationships. Attempts to show a strong correspondence between the findings from tachistoscopic recognition and memory studies have, however, been beset with difficulty. This is due to the fact that differential field effects resulting from such studies are inconsistent and therefore have resulted in a variety of explanations other than that of lateral cerebral dominance. It is proposed that this is due to a lack of understanding of the role of contralateral/ipsilateral optic fiber relationships. The purpose of this study was to support the hypothesis that the contralaterial optic fibers "dominate" the ipsilateral optic fibers. This was accomplished by using reaction time to hemiretinal stimulation as a dependent variable in a "tachistoscopic type situation". Further, a preliminary study was conducted due to the belief that another problem contributing to the inconsistent tachistoscopic findings has been and is the lack of a good method for the control of fixation during stimulation. In Experiment I a monocular lens mounted behind a stimulus screen was used to monitor fixation in a tachistoscopic recognition task. This technique was found superior to the often used "sideview" and as accurate as the method involving identification of a fixation stimulus. It was found that the "telescope technique" is preferable in those studies where presentation of a fixation stimulus might interfere with recognition or report of the experimental stimulus. This was the technique used to monitor fixation in Experiment II. In Experiment II two independent Kodak carousel 35 mm projectors were used for stimulus presentation. Stimulus slides were presented with one projector while the other projector was used to present a symmetrical cross fixation marker in the center of the screen and to maintain a constant illumination level. The subject's task was to depress a standard telegraph key as rapidly as possible when he detected the presence of a small spot of light projected during monocular fixation of the central point. The stimulus was projected without warning and due to adequate auditory masking and projector position there was no possibility for anticipatory responses. The most important finding was a highly superior reaction time to contralateral as opposed to ipsilateral stimulation. The difference in reaction time due to contralateral/ipsilateral stimulation was significantly greater than the difference due to dominant/non-dominant hand reaction time.
dc.format.extent128 pages
dc.identifier.urihttps://hdl.handle.net/1828/18825
dc.rightsAvailable to the World Wide Weben_US
dc.titleReaction time to hemiretinal stimulation.en_US
dc.typeThesisen_US

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