Have you noticed that it is easier to understand what someone is saying when you are looking at them versus when you cannot see them? This is due to sensory interaction. Sensory interaction is the working together of different senses to create experience. We experience sensory interaction when we eat or watch a movie, since the senses are used at the same time. Likewise, the visual aspect of the speech is as important as the hearing aspect. The McGurk Effect displays this, as it is an error in perception that occurs when we misperceive sounds because the audio and visual parts of the speech are mismatched. In this video, the person’s lips make the shape of “bah” and “fah”, and the audio all the way through plays “bah”. However, we hear a change in sound when his lips shape the word “bah” and when his lips shape the word “fah”. This illusion occurs when the auditory component of one sound is paired with the visual component of another sound, leading to the perception of a third sound. The visual information a person gets from seeing a person speak changes the way they hear the sound.
Another example of sensory interaction is synesthesia. Synesthesia is an experience in which one sensation creates experiences in another. Examples are experiencing color when tasting a particular food or by hearing sounds when seeing certain objects. Also, sensory interaction include the experience of nausea that can occur when the sensory information being received from the eyes and the body does not match information from the vestibular system.
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![]() In places around the world, there is a war at different periods of time in history. Though each war is different, there is one common topic that goes around in all wars: friendly fire. Friendly fire is the accidental shooting of one’s solider such as during a battle or during lookout in the nighttime. So why does friendly fire occur? Why might soldiers mistakenly fire on their own soldiers? Well, in the study of psychology there is an accurate answer to that. Friendly fire can be analyzed using signal detection analysis. This is a technique used to determine the ability of the perceiver to separate true signals from background signals. Based on the picture, there four possible outcomes to detect if your signal was accurate: a hit, a miss, a false alarm, or a correct rejection. The spots a person would want to receive is and a hit and a correct rejection because it is a correct response whether the stimulus is present or absent. Based on a specific experiment one chooses to experiment on, such as friendly fire during war, it creates two measures: sensitivity and response bias. People with sensitivity refers to “the true ability of the individual to detect the presence or absence of signals,” much like people who have better hearing or eyesight than people who have a lack of these senses. Another measure is the response bias which is a behavioral tendency to respond “yes” to the trials. In the examples of friendly fire, when a soldier has to look keep watch for any potential threats: one must have a good reflexes or good sense of their surroundings to make the right call of when to shoot. However, depending on the person’s psychological state, one can fluctuate their response bias whether or not to make the right move. When a person is uneasy, they might adopt a lenient response bias. Whether or not this is accurate, your brain still delivers a warning signal. As a result, this can be a good or bad result, which in turn can save or lose lives in war. ![]() Everyone knows that the brain has two hemispheres—the right and the left—which perform specific functions. However, the lesser known but equally important organ called the corpus callosum, is essential to communication between the two hemispheres. The corpus callosum is located above the thalamus and under the cortex. As the largest bundle of nerve fibers in the body, it allows the two hemispheres of the brain to connect through neural messages. By providing a highway for communication, the corpus callosum allows the two hemispheres to synchronize and coordinate. For example, the two hemispheres are lateralized; the left hemisphere will control the right side of the body while the right hemisphere will control the left. One interesting demonstration of brain lateralization was an experiment in 1955 by Ronald Meyers, who discovered the function of the corpus callosum. He trained cats to press their nose against the screen when they saw a circle, but not a square. Then, he cut the optical fibers intertwining between the two halves of the brain, but he did not cut the corpus callosum. So, the left eye was connected to the left brain, the right eye to the right, and both brains were connected by the corpus callosum. Then, he trained the cats to do the same experiment, but only with the left eye. Then he tested them, but using the right eye. If the cats completed the experiment successfully, that would mean the information from the left eye had traveled to the left brain, through the corpus callosum and then to the right brain. The cats successfully completed the experiment, proving the corpus callosum connects the two hemispheres. Meyers took his experiment further by using the same experiment, but this time also severing the corpus callosum; those animals failed, since their hemispheres were not able to relay information to each other. Meyers' experiment proves the importance of the corpus callosum; however, what happens if one loses that integral connection between their hemispheres? In the case of some sufferers of epilepsy, surgeons may cut a part of or completely remove the corpus callusum in an effort to stop epileptic discharges from spreading from one side of the brain to the other. Luckily, the brain is a marvelous learning tool and can be taught to function despite obstacles. Those who have their corpus callosum removed, called split-brain patients, relearn how to perform everyday activities. There have been many studies on split-brain patients; one example is the detailed research experiments of Michael Gazzaniga, who has studied split-brain patients for five decades. One such experiment included a patient who looks at a computer screen that is divided in half, so that the right eye could only see the right side of the screen, and the left eye the left screen. Remember, the right eye of each patient is still connected to the left hemisphere, and the left eye to the right. So, when the right screen flashed a picture, the right eye sent the image to the left brain. Since the left brain is verbally dominant, the patient was able to name the picture aloud. However, when the same picture was flashed to the left eye, the left eye sent the image to the right brain, which could not speak the name of the image aloud, but could use the left hand to draw the picture on a piece of paper. Work cited: http://brainmadesimple.com/corpus-callosum.html http://hubel.med.harvard.edu/book/b34.htm http://www.nature.com/news/the-split-brain-a-tale-of-two-halves-1.10213 https://m.youtube.com/watch?feature=youtu.be&v=zx53Zj7EKQE Today, there are many drugs that mimic neurotransmitters to influence our thoughts, feelings, and behavior. These drugs can reduce or boost the activity of a neurotransmitter.
An agonist is a drug that has chemical properties similar to a particular neurotransmitter and thus mimics the effects of the neurotransmitter. Agonists binds to the dendrites and believing that the drug is the neurotransmitter, decides to excite the neuron. An example of an agonist is cocaine. Cocaine is an agonist for the neurotransmitter dopamine. Since dopamine produces a feeling of pleasure when released by neurons, cocaine creates a similar feeling. There are two types of agonists: direct binding and indirect binding. A direct binding agonist attaches directly to the receptor sites. An example of a direct binding agonist is apomorphine which binds to dopamine receptors. On the other hand, the indirect agonist enhances the amount of neurotransmitters affected but does not have a specific agonist activity at the receptor. It works by working through other means. An antagonist does the opposite job. An antagonist is a drug that reduces or stops the normal effects of a neurotransmitter. When the antagonist is ingested, it binds to the dendrites and stops communication among the neurons. Caffeine is also an antagonist for adenosine, which reduces the adenosine’s effects. Because adenosine typically acts as an inhibitor at the synapse, inhibiting an inhibitor leads to behavior excitation. The antagonists also have direct and indirect acting antagonists. The direct binds and blocks the neurotransmitter receptors. The indirect prevents the release of neurotransmitters. An example of an indirect antagonist is the the drug Reserpine. Buprenorphine is a partial agonist. It activates the opioid receptors but to a much lesser degree than a normal agonist. Buprenorphine also acts as an antagonist, which means that it blocks other opioids while allowing some to suppress the symptoms. There are some differences between the agonists and antagonists. Agonist drugs works at the time of relaxation of muscles, while antagonist drugs works during the phase of muscle contraction. Also, agonist is a substance, which combines with the cell receptor to produce some reaction that is typical for that substance. However, antagonist is a chemical, which opposes or reduces the action. ![]() Consciousness is a complex, comprehensive brain function or a certain state of the mind of which we are aware; it enables activity inspired by knowledge and problem solving. On the other hand the unconsciousness includes mental processes that influence judgements, feelings, or behavior but are cut off from consciousness. Both states always work together. Yet the unconscious mind is the primary source of human behavior. Many of the major theories of psychology, ranging from the Freudian psychodynamic theories to contemporary work in cognitive psychology, argue that much of our behavior is determined by variables that we are not aware of. So how much of the time are we conscious when making decisions? Decisions in the brain are made gradually. But because the unconscious mind contains our biologically based instincts, much of the time we act without thinking consciously. The mind operates best by relaying a significant degree of high level, sophisticated processing to the unconscious. According to cognitive neuroscientists, we are conscious of only about 5 percent of our cognitive activity, so most of our decisions, actions, emotions, and behavior depends on the 95 percent of brain activity that goes beyond our conscious awareness. For example, the motor programs which tell the muscles what to do are all largely unconscious. These processes control which muscle fibers to contract for a certain amount of time. In addition, often times we are unaware of the exact words that will come out of our mouth as the brain chooses what to say when trying to get a point across. Similarly we are not always aware of how the vocal apparatus, which includes the voice box, lips, and tongue, produce the sounds that they produce. When speaking, we are unconscious of all the action that prompts the lips, jaw, and mouth to move the way that they do. This unconscious stimuli is what we call motor codes. Whether we like it or not, the unconscious mind takes control most of the time. But don’t worry, your brain knows what it's doing! |
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