Major Depressive Disorders: Treatments

ELECTROCONVULSIVE THERAPY (ECT)

Description: ECT is considered to be a short-term treatment that is given to patients suffering from major depressions. This therapy works by using electric currents that are passed through the brain causing a brief seizure.This seizure initiates changes in brain chemistry that help reduce symptoms. ECT therapy is used when medications such as antidepressants fail to cure the depression.

When it should be used: Doctors may use ECT therapy when dealing with severe depressions might lead to eating disorders and desires to commit suicide. It also helps to cure catomia (lack of movement), aggressive behavior of people with dementia as well as problems with hyperactivity and euphoria. 

Risks: Some of the side effects of ECT include confusion that might occur after the treatment, especially when curing older adults. Even though ECT is quite safe, physical side effects such as vomiting, headache, jaw pain or muscle might occurs as well. ECT usually increases high-blood pressure and therefore, might lead to some heart problems.

Efficacy: According to the studies and research that was done on ECT, this therapy is very efficient. To be more specific, 41% more effective than placebo and 20% more effective than antidepressant that often used to treat depressions. Doctors usually use ECT when other treatments such as medication failed.

ANTIDEPRESSANT MEDICATION 

Description (in general): antidepressants are drugs that help stimulate the activity and increase availability of neurotransmitters

1. Tricyclic antidepressant (TCas)

Even though Tricyclic antidepressant are effective, they are often harmful and have more side effects than other types of drugs used for curing depression. Therefore, antidepressant are not used very often anymore and have been replaced by other antidepressants. Their main function is to prevent serotonin and norepinephrine from absorbing, so they are more available in the brain. Increases sweating, blurred vision, dry mouth and drowsiness are just a few of many possible side effects TCas have on patients.

2. Monoamine oxidase inhibitors (MAOIs)

In order to ease depression, these antidepressants are able to change the levels of neurotransmitters such as serotonin and dopamine. Part of this treatment is to follow a certain diet. The reason for is that it was found types of food interact with MAOIs while some do not. Therefore, a patient must be careful about what he is eating. Side effects of MAOIs include headaches, low blood pressure, weights gain, dry mouth or insomnia.

Efficacy: It was found that antidepressants do not work for everyone. Interestingly enough, antidepressants have usually a little effect on patients with mild depressions, but at the same time, are very effective when curing severe depressions.

PREFRONTAL LOBOTOMY (leucotomy)

Description: Prefrontal lobotomy can be described as a surgical procedure that consists of cutting nerve pathways found in a lobe from those in other areas of the brain. It is also important to say that lobotomy is a quite simple and very economic way for curing patients, that is why it had been used a lot in the past.

When it should be used: This type of  a treatment has been used to cure many mental illnesses such as schizophrenia, depression and bipolar disorder.

Risks: Since leucotomy had caused many negative side effects such as apathy, decreased ability to concentrate as well as lack of initiative, it is no longer used on regular basis. Other treatments including antidepressants and ECT replaced this older method of curing mental disorders.

Efficacy: Prefrontal lobotomy surgery has a pretty low effectiveness comparing to ECT. Usually only one third of patients undergoing this treatment are cured.

 

COGNITIVE BEHAVIORAL THERAPY (CBT)

Description: CBT is a common way to treat mental problems such as depression. This therapy involves carefully structured sessions, where a person suffering from depression has a chance to talk to a psychiatrist who tries to find a way to help and cure patient's mental problems. The main element of these sessions is to make the patient aware of inaccurate or negative thinking.

When it should be used: There are several issues such as depression, sexual disorders Schizophrenia that can be cured just by introducing emotional challenges. That's when CBT may be very efficient. Moreover, CBT not only learns patient how to cope with stress as well as traumatized life events, but also it helps to reduce symptoms of depression.

Risks: Cognitive Behavioral Therapy fortunately does not have any side effects, which makes it a very safe treatment comparing to Electronegative therapy or antidepressants. However, a patient who is using this type of a treatment might have to reveal and explain several awkward, painful  and often very personal events that he/she would rather avoid.

Efficacy: According to several studies, cognitive behavioral therapy is as effective and antidepressants when dealing with severe depressions. Approximately 60% of participants were cure by having cognitive behavioral therapy.

Why can ethics in psychology be a controversial topic?

Experiments that had been conducted in the last century were often very cruel and had a negative impact on a life of a person or an animal. Harming of people must have stopped and ethics have become a very important element of every psychological study. Nowadays, every experimenter or psychologist, who wants to conduct an experiment must make sure that his/her experiment is ethical. By doing so, we are trying to avoid harming both humans and animals.
Even though conducting of unethical and cruel experiments such as the "Little Albert Experiment" was not a right thing to do, these studies did help to gain knowledge now often used in psychology. On one hand, it was very immoral from J. B. Watson to conduct an experiment on a little orphan who wasn't able to neither agree nor disagree with a participation. What made the whole experiment even more inhuman was that Albert's behavior had completely changed. After the experiment this little boy feared everything that was fluffy and white. On the other hand, Watson's experiment demonstrated the classical conditioning on humans, which was a big contribution to psychology since before classical conditioning was demonstrated just on animals in Pavlov's Dogs Experiment.
Other horrible experiments that have brought many questions were "Monkey Drug Trials." It is well known that  the animal experimentation such as "Monkey Drug Trials" can be incredibly helpful in understanding humans and developing life saving drugs. Psychologists would never use real people for such a dangerous experiment so they decided to demonstrate the effects of drugs on defenseless animals. Monkeys in the experiment were trained to inject themselves with substances such as morphine, alcohol or cocaine. They were arguing that animals do not feel pain. On the contrary, there is a plenty of people who strongly disagree with animal experimentation which has created a controversial topic. People who are against using animals in experiments claim that if animals do not feel pain, then they are probably a lot different than humans. Therefore, it is pretty useless to conduct experiments on animals if they are not like us. Another important fact they often mention is that animals do feel pain and if someone decides to conduct an experiment like "Monkey Drug Trials" then they certainly hurt those animals.Sometimes we should rather ask ourselves if we should not if we can.

Sigmund Freud

The Interpretation of Dreams (1899-1990) 

Throughout the book "The Interpretation of Dreams" written by The "father" of psychoanalysis, Sigmund Freud, the new theory of the psychology of dreams is analyzed. Freud uses his own dreams as examples for proving the theory. In his book, he tries to show a significant distinction between the "manifest" (surface-level) dream content and the "latent (unconscious) dream thoughts." To be more specific, Freud claims that all dreams we have represent the fulfillment of our wishes and that anxiety dreams and nightmares are expressions of our unconscious desires. He uses the special "language" of dreams to explain his dreams. In his book, Freud talks more about the "dream work", which is the process by which the mind translates and distorts "dream thoughts' into dream content. The Interpretation of Dream presents the method called psychoanalysis,  the psychic process of "censorship" and the significance of childhood experiences.

The Ego and the Id (1923)

This analytical study of human psyche talks about three systems: the id, ego and superego that are developed at different stages of our lives.  Freud claims that the id (or it) is the impulsive and unconscious part of our psyche that directly responds to our instincts or needs. It consists of biological components of personality such as the sex instinct "Eros" and aggressive instinct called "Thanatos." The ego (or I) is the part of the id that is influenced by external world and mediates between the unrealistic id and the external real world. The ego functions or operates according to the "reality principle" and uses more realistic strategies to obtain pleasure. The last system is superego (above I) develops during the age of 4 or 5 and focuses on the values and morals of society. It consists of two systems: the conscience and the ideal self. This study is an important part of psychoanalysis. 

Mourning and Melancholia (1917)

Mourning and melancholia is a psychological and psychotherapeutic theory written by Sigmund Freud. One of the basic concepts of this theory is that a person's development is influenced and determined by events that happened in early childhood. It also suggests that human behavior, experience and cognition are determined by irrational drive that are usually unconscious. Freud claims that when the person becomes aware of his drives then he uses psychological resistance called "defense mechanism." This defense mechanisms is used to protect a person from mental disturbances created by conflicts between conscious and unconscious. He also believes that mourning is a natural process while melancholia is a pathological one.

On The Sexual Theories Of Children (1908)

It's Freud's article that is part of a whole set of writings, in which he focused on the role of childhood sexuality  as well as on sexuality in general. Freud claims that the child's curiosity about where he cam from arises from a "vital exigency" called Lebensnot. In his article Freud introduces three theories. The first one consists in the attribution to all human beings of a penis-including females and suggests the belief in a castration that accounts for the configuration of the woman's genitalia. The second theory concerns birth and claims that "the baby is evacuated like a stool from the mother's body." The last one deals with parental coitus. It pictures it as struggle where the mother is attacked by the father. In Freud's view, the wish to know is more like a sexual wish.

Experiments in Intergroup Discrimination

Name: Under-estimators and over-estimators experiment conducted by Henri Tajfel (1970)

Aim: The aim of Tajfel's study was to demonstrate that categorization of people is sufficient for people to discriminate in favor of their own group and against people of the other group.

Participants: The participants were 64 boys of ages 14 and 15 from a school in a suburb of Bristol.T

Procedure: The participants were divided into 8 group. All of the boys in each group knew each other. The boys then were told to go together to the lecture room. In the lecture room the researcher told them that the experiment was interested in the study of visual judgments. Then forty clusters of varying numbers of dots were flashed on the screen. The boys were asked to record each of them. In this experiment were two conditions and the researchers made sure 4 groups of 8 served are in each condition. After they finished the test the boys who were in 1. condition groups were told that some people constantly overestimated the number of dots and some consistently underestimate the number of dots. In the 2. condition groups the boys were told that some of them were always more accurate than the others. After the judgments had been made the boys were told they were going to be divided into new groups according to the visual judgments they had just made. The truth is that the participants were randomly assigned to the groups. Then the researchers gave the participants another task. They were given a booklet of matrices and were told to give other students/participants rewards and penalties in real money. The boys did not know the identities of people who they were giving rewards and penalties. The boys were asked to three types of choice:

1. in-group choices: both top and bottom row referred to members of the same groups as the boy.
2. out-group choices: both top and bottom row referred to members of the different group from the boy.
3. inter-group choices: one row referred to the boys' own group and the other one to the other group.

Results: The researchers found out that in in-group and out-group choices participants gave the same amount of money to all members. However, in inter-group choices most of the participants gave more money to  members of their own group than to  members of other groups.

Conclusion: The experiment conducted by Tajfel demonstrates that inter-group discrimination is quite easy to trigger off. It also shows that categorization of people into groups leads to conflict.

Strengths: Tajfel made sure that he had the high-level of control on the procedure (for example when students were awarding points to other students they did not know their names).

Limitations: One of the limitations was that the experiment wasn't done naturally but in the laboratory. Tajfel's experiment was criticized for being ecologically invalid.

Cultural Differences: None

Errors of Attribution

Attribution errors

It's a psychological term for describing a process of inferring the cause of events or behavior without being aware of the underlying processes and biases that lead to those inferences.

Self-Serving Bias

It's an attribution error in which you attribute your success to your internal abilities like talent and your failure to external forces (outside variables). For example: when you win a basketball game, you attribute the win to your physical abilities or talent. However, when you lose  you put blame on the referrers. Psychologists and researchers believe that by doing this people just try to protect their self-esteem.

 Self-Serving Bias in Children

a) This study was conducted by Elizabeth Posey and Randolph A. Smith from Ouachita Baptist University

b) Its aim was to investigate self-serving bias in children (the study provides evidence of self-serving bias). Twenty male and 16 female second graders were participating in this experiment. These children were paired with with a partner of same gender and were asked to complete 3 minutes math worksheet as a group. However, one half of the participants was paired up with a friend while the other one was not. At the end all of them received feedback that indicated their success or failure.

c) The results showed that the people in non-friend groups were blaming the failure or the bad performance to their partners. When they were asked who did better job they tended to give a credit for themselves. On the contrary children who were paired up with a friend were less likely to blame others or external/situational factors for their failure.

d) Participants who were blaming others for the failure clearly demonstrated self-serving bias. By putting the blame on their partners children wanted to protect their ego or self-esteem.

Cultural Differences in Relation To The Self-Serving Bias 

a) This study was conducted in 1986 by Kashima and Triandis

b) 34 Japanese graduate students and 202 American undergraduate students participated in this experiment. The participants were shown and then asked to remember 15 slides pertaining to life in Israel, Greece and Iran. Then they were given 5-minute recognition test that was based on those slides. After the test the participants were shown 5 slides pertaining to life in India. Then they were given 3-minute test based on those 5 slides about India. Participants were randomly assigned to either success or failure group. People in the success group were told they scored 12/15 while the people in the failure group were told they scored only 5/15. Then all of the participants were given an attribution questionnaire.

c)American students tended to attribute their success to their talent or abilities. (Self-serving bias; individualistic country)

  Japanese students tended to attribute their failure to lack of their abilities. (Modesty bias; collectivist culture)

  Both Americans and Japanese students responded similarly when they were given situational information

Importance of Situational Factors

Milgam's studies of obedience to authority (1974)

Aim of the study: By conducting this experiment Milgram wanted to find out how far people would go in obeying an instruction that involved harming another person.

Participants:  The participants were forty men who were randomly chosen. They got paid for taking part in the experiment (approximately $4). Milgram and his team used newspaper ads to find the participants.T

Procedure: Milgram developed intimidating shock generator which had shock levels starting at 30 volts increasing all the way up to 450 volts. The switches were labeled as "slight", "moderate" and "danger" shock. The last two switches were labeled with "XXX" which represented death. The participants were divided into two groups: 1. Teachers and 2. Learners. Teachers were asking learners distinguish questions. For every wrong answer, the teacher delivered the learner an electric shock. The truth was that the learners just pretended to be shocked, but the teachers did not know about it. As the experiment progressed, some of teachers wanted to quitt. They felt guilty about harming people. However, when the instructor told them that it was not their responsibilty, they continued in the experiment and delivered next shocks. In the end of the experiment, Milgram told the participants that they were deceived and that nobody was harmed.

Results: What the Milgram and his team found out was that more than 65% of the participants delivered the maximum shocks. After Milgram told them the truth, unexpectedly more than 85% of the participants said they  were glad to have participated.

Conclusion: This experiment demonstrated the danger of obedience. It also confirmed that the situational variables really did have (and still do) a strong impact on a person's behavior. Following order might be very dangerous.

The Asch Conformity Experiments (1956)

Aim of the study: By conducting this experiment, Solomon Asch wanted to demonstrate the power of conformity in the groups. He basically wanted to investigate the extent to which social pressure  from a majority group could affect a person to conform.

Participants: 123 males from Swarthmore College in the USA participated in this experiment.

Procedure: Asch put one real participate in a room with four to six confederates who had agreed before the experiment what their responses would be. The real participant did not know this and thought they are normal participants like he is. Then each person in the room stated aloud which comparison (A, B or C) was most like the target line. The answers were always obvious. The real participant always gave the answer last. Sometimes confederates gave the wrong answers on purpose. There were 18 trials in total and the confederates gave the wrong answers on 12 trails - critical trials.

Results: About one third (32%) of the real participants went along and conformed with the incorrect majority (confederates) on the critical trials. Over the 12 critical trials about 75% of the participants conformed at least once.

Conclusion: After the experiment Asch asked the real participants why they conformed so readily. Most of them said they didn't really believe the answers of the confederates, but they went along with the group for fear of being thought peculiar.

Zimbardo's Stanford Prison experiment (1971)

Aim of the study: Zimbardo wanted to investigate how readily people would conform to the roles of guard and prisoner in a role-play exercise that stimulated person's life.
Participants: 21 male college students were screened for psychological normality and paid $15 for taking part. These students were chosen from 75 volunteers.
Procedure: Zimbardo used a basement of the Stanford University for building a mock prison. Then participants were randomly assigned to either the role of prisoner of guard. In order to make the experiment as real as possible, Zimbardo told guards to arrest prisoners at their own homes and to take them to the local police station. From the police station they were taken to the prison at the Stanford University. These fake prisoners were treated like every other criminal. (prison clothes, were locked away,Guards were wearing khaki uniforms having whistles and handcuffs. They were also wearing dark glasses to make eye contact with prisoners impossible.
Results: Zimbardo noticed that the guards adopted to their roles quickly and easily. Yet some of them began to harass the prisoners and apparently enjoyed it. The guards treat them terribly and the prisoners started being tormented both mentally and physically. However, the prisoners soon adopted prisoner-like behavior too. (started taking the prison rules very seriously) Some of the prisoners started to be released after 36 hours because of uncontrollable bursts of screaming, crying and anger. Zimbardo had to close down the experiment on the sixth day. 
Conclusion: People can readily conform to the social roles they are expected to play. The roles the people play can shape their personality as well as their behavior (actions). Interesting was that after the experiment most of the guards couldn't believe that they had behaved in the cruel ways that they had.

Sherif: Ambiguous situation (1935)

Aim of the study: Sherif's aim was to demonstrate that people tend to conform to group norms when they are in an ambiguous situation.
Procedure:   In his experiment Sherif used the autokinetic effect. He projected a small spot of light onto a screen in a dark room which made the light looked like it was moving-visual illusion. First, the participants were tested individually. They were asked to say how far the light moved. Then they were tested in groups of three. However, the composition of the groups wasn't random. The group was composed of two participants whose estimate of the light was very similar and one person whose estimate was very different. Each participant was asked say aloud how he/she thought the light had moved. 
Results:  The results showed that most of the time the person whose estimate of movement of the light was different to the other two in the group, later conformed to the view of his partners. 
Conclusion: When a person is found in an ambiguous situation, he or she tends to look to others for guidance or adopt the group norm. The person would tend to conform rather than to make an individual judgement.
Limitations: Since it was a laboratory experiment, there was no ecological validity. Another limitation would it be that the experiment is lacking cross cultural validity.
Strengths:  A high level of control on the procedure.

Biology & Technology

CT which stands for Computed Tomography scan is a medical imagining method that uses computer processed X-rays to produce tomographic images or slices of specific areas of the human body. This scanner emits narrow beams through the human body as it moves through an arc. Inside of the scanner there's X-rays detector that can see tissues in a solid organ and different levels of densities. Then it sends  the data to the computer and the final 3-D picture full of details is made.CT scan is used in medicine for detecting chronic changes in the lung parenchyma and for showing structural changes in the brain (for example: structural changes due to a brain tumour). The case of Janet: after Janet's death doctors found out by using CT scan that a reason why she blew out the candles only on the right side of the cake and why she often used only the  right side of the page is due to brain tumour that damaged only one side of her.

Positron emission tomography (PET) is a nuclear medical imaging technique that requires the injection of a radioactive substance into the person. This radioactive substance which is usually a form of sugar, produces gamma rays as they are metabolized by the brain. The parts of the brain metabolize the sugar at different rates according to how much active they are.The gamma rays are detected by the machine in which the participant is placed and then the signal is turned into a computer image that shows the activity in different parts of the brain. PET is used for showing a dynamic image of the brain activity and it's a helpful diagnostic tool that can show abnormalities in activity levels. When someone has Alzheimer's disease, PET is able to show doctors dramatic differences in the brain structure when the disease has progressed and then it can easier explain the person's behavior.

fMRI or, in other words, functional magnetic resonance imaging is a procedure that measures brain activity by detecting the changes in blood flow. fMRI is based on the discovery that when the body is exposed to a strong magnetic field, the protons in the water inside of the body change their alignment. By using radio frequency fields, hydrogen atoms are changed so they can be detected by a scanner that eventually creates an image of a part of the body or the brain being studied. The image shows which parts of the brain are active while certain activities are being performed. It can be used to make a three-dimensional image of the brain as well. fMRI allows human behavior, thoughts and emotions to be correlated with brain activity as they happen. It helps us to understand the way certain parts of the brain function. fMRI is much flexible than original MRI and it's able to provide dynamic information.

Twin Studies

Twin studies are studies that involve both monozygotic (identical) and dizygotic (fraternal) twins. The purpose of these studies is to measure the contribution and the effect of genetics, as opposed to environment, to a particular trait. They allow the effects of nurture which is environment and nature (heredity) to be investigated. The classical twin study relies on studying twins who are raised in the same environment like in a family and compares the similarities between identical twins who share all of their genes, with fraternal twins sharing only 50% of their genetics for a trait. By examining how often certain traits occur in identical and fraternal twins, we are able to estimate how much genes affect these traits. Researchers assume that any likeness between monozygotic twins is due to genetics. However, the modern twin studies specialize more on the pairs of identical twins who are raised apart, and therefore they do not share the same environment. An example of the modern twin studies is a psychological study called The Minnesota Study of Twins Reared Apart (MISTRA) which began in 1979, at a time when people supposed that intelligence and personalities were only influenced by the environment. The basic design of MISTRA relied on finding identical twins reared apart and seeing what traits they had in common. MISTRA had used more than 81 pairs of twins from which most of them were often separated right after infancy. For instance, genetically identical twins Jim L. and Jim S. were reared apart since infancy and were first reunited at age 39. Researchers found many interesting similarities between them like: both of them had had a dog called Toy. Each of them bit his fingernails and had headaches. Both Jims were first married to a woman called Linda and then to Betty. Each had worked at a gas station, smoked cigarettes and liked the same brand of a beer. Jim L. and Jim S. had even similar voices, gestures and mannerisms. By using twin studies we can estimate how much the particular trait is affected by genes. These studies also allow us to study the influences of genes on medical studies. Even though the twin studies might have many benefits, there are several limitations as well. The major disadvantage is that there are only a certain number of twins which means that twin studies do not represent the whole society. Therefore, the generalizability of the results may be limited. In the classical twin study, one of the main limitations is that as the twins are raised in the same environment we cannot really predict the effects of nurture on certain traits. On the other hand, a disadvantage of the modern twin studies is that the twins who were reared apart had often different personalities which must had been due to growing up in the different household then. Along with twin studies, there are many ethical issues too. In many cases, in order to conduct a psychological study, researchers decided to separate newborn twins. Sometimes, these twins weren’t even told of having a twin! So is it right to take a baby away from its parents and its twin in the name of science?

Genetics & Twins

Twin studies are studies that focus on the importance of environment and genetics as well as on the way they affect individual traits and behaviors. The classical twin study focuses on studying twins who are raised in the same environment (family). For the decades, researchers observe similarities for the particular trait between fraternal and identical twins and predict that the similarities between identical twins are due to same genes rather than environment. Modern twin studies also try to determine the effect of a person's share environment like family as well as the effect of a person's unique environment like individual events, on a trait.

Adoption studies are designed to evaluate genetic and environmental influences on phenotype.  They provide a model research where biological effects can be estimated. These studies are often very helpful in uncovering interactions between genes and environment in psychiatric and complex behavioral disorders.

MISTRA which stands for The Minnesota Study of Twins Reared Apart, is one of the most important and interesting psychological studies. This study overthrew the dogma that said intelligence and personalities were caused and mainly affected by the environment. It was designed to see how different monozygotic and dizygotic twins reared apart are. For this experiments 81 MZA and 56 DZA twin pairs were used. The twins had been separated mostly before age four. What they found was that similarities between the twins are due to genes and dissimilarities must be the result of the environment.

Stroke: An Assault on the Brain

1. Explain what happens to the brain when a stroke occurs.

The brain is damaged due to lack of blood. When the blood supply fails, nerve cells stop receiving oxygen and brain damage occurs.

2. Briefly explain the differences between the three different types of strokes.

a) Ischemic Stroke: is caused by a blood clot (thrombus) that occurs in an artery and blocks the flow of blood to a part of the brain. b) Hemorrhagic Stroke: it occurs when a blood vessel ruptures inside of the brain. c) Transient Ischemic Stroke: it's a mini stroke and it occurs when a blood clot blocks an artery for a short time.

3. Identify some of the most common risk factors - in other words, who is most likely to have a stroke?

There's two types of risk factors: controllable and uncontrollable. Controllable risk factors are high blood pressure, high cholesterol, smoking, alcohol use, diabetes and overweight. Uncontrollable risk factors are family history, age, gender, history of previous strokes.
 

4. What disabilities can result from a stroke?

Stroke may cause: problems with thinking, learning, memory, attention, paralysis (even on one side of the body), problems with understanding and speaking, emotional problems and pain.

5. What is brain plasticity and what does it mean in terms of recovering from a stroke? 

Brain plasticity is basically the ability of the brain to change, physically, functionally, chemically, throughout the life. Because of the brain plasticity, stroke patients who have lost the ability to speak or to move a limb have a chance to regain function after several weeks of convalescence (use of neuro-imaging techniques).

Sperry and Gazzaniga: The Split Brain Study

What does it mean for a person's brain to be "split"?

When a person's brain is split it means that corpus callosum which connects 2 halves of the brain is cut off.

What was the reason why this procedure was performed on patients?

When someone suffered from epilepsy (kind of a storm in the brain), doctors used to cut off corpus callosum to prevent spreading of epilepsy to the other hemisphere.

Explain one of the tests Sperry and Gazzaniga performed on these split brain patients. 

Their first patient was a soldier who had started having problems after a German soldier clocked him in the head with a rifle. After the operation Sperry and Gazzaniga ran an experiment in which this soldier was supposed to press a button whenever he saw an image. Researchers then flashed images of letters and other stimuli. For the stimuli delivered to the left hemisphere, the soldier simply pressed the button and said what he saw. It was different for the stimuli delivered to the right hemisphere. He couldn't verbally say what he saw but his left hand kept pressing the button every time an image appeared. 

What were the results of this test?

Left hemisphere is dominant for verbal processing that's why the patient's answer matched the word. The right hemisphere cannot share information with the left, so he couldn't say what he saw but he was able to draw it or press the button.

What is the reason that these results occurred?
The reason is that the brain is divided into many parts and every part of the brain has its own function. Each of the parts works independently.

What is the corpus callosum and what role does it serve in your brain?
It's a flat bundle of neural fibers that connects the left hemisphere of the brain with the right. It facilitates communication between two hemispheres.