Attention is the mental process in which a person concentrates awareness on a specific object, issue, or activity and excludes other potential stimuli * from the environment. While the human brain has amazing capabilities for processing information, it also has limited capacity. A person cannot attend to all the information being received through the five senses (sight, hearing, taste, smell, and touch) at any one time.
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Attention deficit disorder (ADD)
What Parts of the Brain Are Involved
in Paying Attention?
Neuroscientists (nor-o-SY-in-tists), or scientists who study the brain and nervous system, believe that attention is largely a function of the brain's reticular activating (re-TIK-yoo-lur AK-ti-vay-ting) system, or RAS. This system includes a group of nerve fibers located in several parts of the brain, including the thalamus * , hypothalamus * , brain stem * , and cerebral cortex * . The RAS seems to account for the shifts in people's level of involvement with their surroundings, which ranges anywhere from full attention to sleep. When the system is fully operating, a person is awake, alert, and attentive; this would be the case when a person is listening to an interesting lecture or taking an important test. When the RAS is less active, a person is tired or inattentive. The highway signs urging drivers to "Stay Awake - Take a Break" actually are related to the RAS; it is much more difficult for people to pay attention when they are tired.
Within the RAS, the thalamus appears to play a key role in the moment-to-moment changes in the focus of attention. The thalami and cerebral cortex cooperate to register any incoming sensory signals, evaluate their contents, and mobilize brain resources in response to the demands made. Put simply, the thalami receive the messages that come through a person's senses and then relay the information to the proper receiving areas in the brain.
* stimuli (STIM-yoo-lie) are things in the environment that "excite" a person to function, become active, or respond. The singular form is stimulus.
* thalamus (THAL-uh-mus) refers to a pair of large egg-shaped areas located in the middle of the brain just under the cerebral cortex. The plural form is thalami.
* hypothalamus (hy-po-THAL-uh-mus) is a brain structurelocated deep within the brain that regulates automatic body functions such as heart rate, blood pressure, temperature, respiration, and the release of hormones.
* brain stem connects the brain to the spinal cord. Twelve pairs of nerves branch off the brain stem and connect to the eyes, ears, nose, face, neck, and breathing and swallowing muscles. The brain stem is involved in motor functions, reflexes, and sensing.
* cerebral cortex (suh-REE-brul KOR-teks) is the part of the brain that controls functions such as conscious thought, listening, and speaking.
Chemical messengers known as neurotransmitters (nor-o-TRANZ-mit-erz) are also involved in the process of paying attention. In fact, all of the systems within the brain depend on chemicals that pass electrical signals from nerve cell to nerve cell. A test known as electroencephalography (e-LEK-tro-en-sef-uh-LAH-gru-fee), or EEG, can measure electrical signals within the brain. Two transmitter substances, noradrenaline (nor-uh-DREN-uh-lin) and dopamine (DOH-puh-meen), play important roles in helping people stay alert and attentive. The medicine methylphenidate (meth-il-FEN-ih-date; better known by its brand name, Ritalin ® ) is used to treat Attention Deficit Hyperactivity Disorder and is thought to work by regulating the levels of key neurotransmitters in the brain, particularly dopamine. After taking the medicine, people who have difficulty focusing their attention are better able to concentrate on a task.
During the twentieth century, researchers developed a better understanding of what it really means to pay attention. A few key developments include:
- 1920s: A Russian scientist named Ivan Petrovich Pavlov observed some of the physical signs of attention in dogs and other animals, which came to be known as the orienting response. These signs included pricked-up ears, turning the head toward the stimulus, increased muscle tension, and other changes in the body. In his most famous experiment, Pavlov found that he could train dogs to associate the ringing of a bell with the delivery of food. Pavlov's discovery gave rise to a school of psychology known as behaviorism, which studies how behavior is caused by the brain's responses to external factors.
- 1950s: The theory of the bottleneck is used to describe the process of attention. Scientists theorize that the many signals entering the central nervous system are placed in temporary storage and then are analyzed for their importance. In this way, a person can filter out what needs attention and only allow those signals to pass through for further processing in the brain.
- 1990s: The development of new scanning technologies such as positron emission tomography (POZ-ih-tron e-MISH-un tuh-MOG-ruh-fee) (PET scan) and magnetic resonance imaging (mag-NE-tik REZ-uh-nans I-muh-jing) (MRI) allows researchers to watch the brain in action. For example, researchers at Duke University in North Carolina recently used a MRI scanner to take 480 snapshots per minute of the brain activity of several volunteers as they watched a computer-controlled television screen. The scans showed how areas of activity in the brain shift as the person shifts attention. Many other studies have used this technology to determine how different areas of the brain are involved in different activities.
This is an overly simplified explanation of a complex process. There are other parts of the brain and nervous system that play a role in the process of paying attention. For example, a group of structures in the middle of the brain compose the limbic (LIM-bik) system, which is linked to various emotions and feelings such as fear, pleasure, and sadness. These structures are thought to play some role in how people decide to focus their attention. For example, when a student sits at a desk to read a school textbook, a variety of complex emotions may play a role in her decision to focus on the text: pleasure in the subject matter, fear of doing poorly on the next test, desire to perform well during class discussion, and so forth. To focus in on the task at hand, she must tune out all other stimuli, such as the other books scattered around the room, the sound of children playing outside, the color of the desk pad, and the ticking of the clock. Attention is not always under a person's control, however. If someone comes bursting into the room or turns on a stereo at full volume, the student's attention would likely be drawn away from the book. Thus, attention may be captured by an unexpected event rather than voluntarily directed toward it.
Do Television and Video Games Affect Attention?
Some experts have argued that watching too many fast-paced television programs and video games may actually increase the likelihood of attention problems. If the brain becomes accustomed to constant stimulation by rapidly changing visual effects, it may easily become impatient with tasks that require closer attention. Television also makes fewer demands on attention than do reading, studying, or playing a game. Without enough of these more challenging activities, the brain may "get out of shape."
However, the reverse may be true. Children and adults with limited attention resources may be attracted to intense stimulation and therefore may be captured by television or video games. Less intense activities may not hold the focus of individuals with attention deficits. More research is needed to better understand this issue.
Neuroscience for Kids is an extensive and entertaining website
maintained by Research Associate Professor Eric Chudler at the
University of Washington, Seattle. It features easy-to-understand
information on a range of topics related to the brain and nervous
system, including attention.