The Concept of Brain Asymmetry - Research Paper Example

? BRAIN ASYMMETRY In a neuroscience perspective, the concept of brain asymmetry is closely tied to the hemisphere of the human brain. The mirror symmetrical organization of the body along the vertical axis produces two mirror body halves. The two hands are regarded as almost anatomically wonderful mirror images of each other. However, there are asymmetrical in regards to physiology. The human brain is a complex structure that is able to control the cognitive behavior. Anatomically, the cerebral cortex is divided into four lobes. About 90% of the population are right handed for most of the manual activities and have superior fine motor control and strength. The concept of left and right handedness poses an imperative conceptual distinction between object, functional, and activity related. There is also a similar distinction that applied to the two cerebral hemispheres, which appear to be symmetrical mirror images. In the human brain, there are distinct functions that tend to be localized in the left or right hemisphere. The cerebral cortex can be divided into the two hemispheres. The left hemisphere is usually dominant for language and logic processing. The right hemisphere is specified for spatial recognition. Each human being has two distinct hemispheres of the brain that have different capabilities. The sensory signals that are in the left side are sent to the right hemisphere of the brain and those on the right side of the body are sent to the left hemisphere of the brain. It has been noted that the left hemisphere sub serve linguistic functions while that of the right hemisphere are specialized for spatial function and emotional control. For example, controlling of your right arm is via left hemisphere and the control of your left arm is via your right hemisphere. There are also various cognitive differences that exist. There are many experiments that have failed to show much difference between the two hemispheres in normal humans. However, this is not to suggest there are not, but the functional significance may be slight. The experiment uses a technique that was devised by Levy, Heller & Burton (1983). For demonstrating differences between the hemispheres of a normal subject’s brain, the stimuli of chimeric faces are used. A chimerical face is designed by making two different faces in half and combining them. The subjects will the view the two chimeric faces and decide which one more strongly describe a particular quality this experiment. For example, in this experiment it will deal with age. If the chimeric faces are constructed so that the two haves have difference in quality of the specified characteristic the information will go the different brain hemispheres. The choices made by subject will show a disparity towards the information that that goes to the right hemisphere that will seem to be more involved than that of the left hemisphere when making judgment about faces. The expected effect is weaker for the left handed people than those of the right handed people as the former will show differences between the left and right hemisphere. Method and design This experiment was based on the technique of Rueckert (2005). For each trial of the experiment, two chimeric faces were shown and the participant is asked to indicate which one is younger. The two faces are mirror images of each other so they had identical age information. Based on characteristics of the images, we expect no preference for one image over the other. The independent variable for this experiment is the construction of the chimeric faces. For one of the faces, the left side of the face was younger than the right side of the face. The time is also independent. The dependent variable is of this experiment is the handedness. A participant can either be right handed or left handed. The experiment is found on Coglab . The levy et al. (1983) chimeric faces task was replicated in a web page. Results Data summary for experiment Brain Asymmetry, version Right handed. 2012-02-09 08:52:15 Eastern Standard Time In this experiment a participant was in one of 2 versions: Right handed Left handed You were in version: Right handed.  Different versions are based on self-reports of handedness. For right-handed people, the right hemisphere of the brain is more likely to be involved in making judgments about facial qualities (including age). Parts of the visual scene on the left side of eye fixation are sent to the right hemisphere, so the expected pattern of results for right-handed observers is that they report that the chimeric face with the younger half on the left will look younger than the mirror image (with the younger half on the right). In contrast, left-handed people tend to not show the brain hemisphere differences as strongly as right handed people. Thus, the expectation is that the percentage of reports that the chimeric face with the younger half on the left looked younger will be smaller for left-handed people than for right-handed people. If the effect exists, it may be stronger for the group or global averages than for your individual data. Data summary Percentage of choices with younger half face on left 35.714287 Trial-by-trial data On every trial, one face is a mirror image of the other. Each face consists of half an older face and half a younger face. The photos are identified by whether the chosen chimeric face had the younger half face on the left or on the right.  Trial Participant Face presented first Face presented second Chosen chimeric face 1 philaucog-11 Younger half on right Younger half on left Younger half on left 2 philaucog-11 Younger half on right Younger half on left Younger half on right 3 philaucog-11 Younger half on left Younger half on right Younger half on right 4 philaucog-11 Younger half on right Younger half on left Younger half on right 5 philaucog-11 Younger half on left Younger half on right Younger half on right 6 philaucog-11 Younger half on right Younger half on left Younger half on right 7 philaucog-11 Younger half on right Younger half on left Younger half on right 8 philaucog-11 Younger half on right Younger half on left Younger half on left 9 philaucog-11 Younger half on left Younger half on right Younger half on left 10 philaucog-11 Younger half on left Younger half on right Younger half on right 11 philaucog-11 Younger half on right Younger half on left Younger half on right 12 philaucog-11 Younger half on left Younger half on right Younger half on right 13 philaucog-11 Younger half on left Younger half on right Younger half on left 14 philaucog-11 Younger half on left Younger half on right Younger half on left Discussion The results of this experiment replicated those that were gotten from previous studies by Levy, Heller & Burton (1983) and Rucckert ( 2005). It was deduced that regardless of gender, there was more attention to the left side of the chimeric faces. The results from the Coglab show that some measures of cerebral asymmetry can be reliably administered via the Coglab web page. Participants that took the experiment via the web exhibited the expected leftward bias on a chimeric face task. The right handed participants chose the chimera which had a younger half of the left on about 73% of the trials while the left handed participants chose the younger left chimera on 67% of the trials. In addition, the fact that the leftward bias observed in this experiment was slightly greater than that of other studies. This shows that there is increased variability in the task administration like the computer screens. In this experiment, we learn about hemispheric lateralization. It is imperative to note that a functional asymmetry between the two hemispheres. The experiment has shown that the left hemisphere seems to be better at verbal tasks like speech processing, whereas the right hemisphere will exceed non verbal tasks such as face recognition which also entails spatial skills. This experiment uses the technique that was devised by Levy et al. and Ruceckert. On each trail of the two chimeric faces have been participant and to determine which of them appeared younger. This is used to establish the different behavior for right and left handed observers. Those participants that right handed, the right hemisphere tends to be more strongly involved the judgment of faces than the left hemisphere. Additionally, when staring at the middle of the face, the information that is to the right of fixation is directed to the left hemisphere initially (Rueckert, L.2000). The left handed people do not show as strong difference between the left and right hemisphere. That is why the results have shown that the left handed subjects will less often chose the chimeric face that has the younger half on the left side. It is noted that the left participant should have a smaller percentage (67%) than the right handed participants (73%) of the total trials. These results are important as they provide a standard control due to the fact that the bias that is between right handed subjects is not from a general left view perception that might arise from living in a world of people that read from left to right. Nonetheless, the two hemispheres look mirror images of each other at a first glance (Levy, J., Heller, 1983). When the participants take a closer look at it we can see that the hemisphere differs in various characteristics such as chemistry, conformation and also in their function. The right hemisphere has better facial recognition than the left hemisphere. This experiment show the difference between the left handed people on the basis that is imperative and exist in many occasions. References Rueckert, L., & Pawlak, T. (2000). Individual differences in cognitive performance due to right hemisphere arousal. Laterality, 5, 77-89 Rhodes, G., Brake, S., Taylor, K., & Tan, S. (2009). Expertise and configural coding in face recognition. British Journal of Psychology, 80, 313-331. Levy, J., Heller, W., Banich, M., & Burton, L. (1983). Asymmetry of perception in free viewing of chimeric faces. Brain & Cognition, 2, 404-419 Kucharska-Pietura, K., & David, A. S. (2003). The perception of the emotional chimeric faces in patients with depression, mania Read More