Essay On Hand Selection

1213 Words 5 Pages
Decisions in life are inevitable, and although unavoidable, a majority of the decisions made with everyday behavior are repetitively overlooked. One of the most frequently disregarded decisions made in everyday life is which hand to use when performing actions such as grasping, writing, lifting, and gesturing. Copious studies suggest that the posterior parietal cortex is of paramount importance when executing hand actions and motions. Comparatively, past experiments exhibit bilateral posterior parietal cortex activation during one-handed movements with notable increases in the activity of the hemisphere contralateral to the active hand. Because posterior parietal cortex activity levels indicate relationships to hand choice, there are postulations …show more content…
The first experiment of the study was conducted on six right-handed female participants that ranged from eighteen to twenty-one years old. The second experiment of the study was conducted on two right-handed female participants that ranged from twenty-one to thirty-three years old. The control group of the study consisted of six right-handed female participants that ranged from twenty to twenty-four years old. To analyze the influence of hand selection on reaction times, each participant in experiment one performed trials of one-handed reaches as quickly and precisely as possible to a visual target that varied in location among a semicircular display. To obtain comparable data, experiment one was conducted under three varied conditions. The first and second conditions were predetermined in which participants could only use one hand (right for the first condition, left for the second condition) to reach for the target. During the third condition, participants were allowed to use either the right or left hand to perform the reaches toward the target as long as they responded in a timely manner. Each participant completed fourteen randomly assigned blocks of forty-eight trials (six choice, four right, four left). Reaction times for each of the three conditions in experiment one were then analyzed and compared. In the second experiment, the researchers investigated the influence of …show more content…
This finding suggests that a possible threshold of movement or activity needed to elicit responses is increased during times of indecisiveness. The hypothesis that stimulation causes increased probability that hand movements will be performed with the hand ipsilateral to the stimulated site was supported by data obtained from stimulation to the left posterior parietal cortex but was not supported by data obtained from stimulation to the right posterior parietal cortex. The asymmetry within these findings suggests that the posterior parietal cortex is involved with hand selection, however the extent of involvement remains unknown. These findings create questions regarding the specific roles and involvement of the left and right posterior parietal cortices. The outcomes of this experiment suggest that the left posterior parietal cortex is involved in control of the right and left hand whereas the right posterior parietal cortex is involved in control of only the left hand. A notable methodological limitation in this study is sample size. The sample size of six participants in experiment one and two participants in experiment two provided limited data. A second limitation is a narrow participant population in which participants selected were all of the same gender. Because of the small sample size, it is possible that there are confounding

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