Attention
Encyclopedia
Attention is the cognitive process of paying attention to one aspect of the environment while ignoring others. Attention is one of the most intensely studied topics within psychology
and cognitive neuroscience
.
In 1890, William James
, in his textbook Principles of Psychology
, remarked:
Attention remains a major area of investigation within education
, psychology
and neuroscience
. Areas of active investigation involve determining the source of the signals that generate attention, the effects of these signals on the tuning
properties of sensory neurons, and the relationship between attention and other cognitive processes like working memory
. Another ongoing line of research involves studying how attention is disrupted early in the development of different disorders, and how abnormalities in the allocation of attention can affect subsequent learning.
. However, as early as 1858, Franciscus Donders
used mental chronometry
to study attention and it was considered a major field of intellectual inquiry by authors such as Sigmund Freud
. One major debate in this period was whether it was possible to attend to two things at once (split attention). Walter Benjamin described this experience as "reception in a state of distraction." This disagreement could only be resolved through experimentation.
during what has come to be known as the "cognitive revolution
". The cognitive revolution admitted unobservable cognitive processes like attention as legitimate objects of scientific study.
Modern research on attention began with the analysis of the "cocktail party problem" by
Colin Cherry
in 1953. At a cocktail party how do people select the conversation that they are listening to and ignore the rest? This problem is at times called "focused attention", as opposed to "divided attention". Cherry performed a number of experiments which became known as dichotic listening
and were extended by Donald Broadbent
and others. In a typical experiment, subjects would use a set of headphones
to listen to two streams of words in different ears
and selectively attend to one stream. After the task, the experimenter would question the subjects about the content of the unattended stream. Experiments by Gray and Wedderburn and later Anne Treisman
pointed out various problems in Broadbent's early model and eventually led to the Deutsch-Norman model in 1968. In this model, no signal is filtered out, but all are processed to the point of activating their stored representations in memory. The point at which attention becomes "selective" is when one of the memory representations is selected for further processing. At any time, only one can be selected, resulting in the attentional bottleneck.
This debate became known as the early-selection vs late-selection models. In the early selection models (first proposed by Donald Broadbent
and Anne Treisman
), attention shuts down or attenuates processing in the unattended ear before the mind can analyze its semantic content. In the late selection models (first proposed by J. Anthony Deutsch and Diana Deutsch
), the content in both ears is analyzed semantically, but the words in the unattended ear cannot access consciousness. This debate has still not been resolved.
Anne Treisman
developed the highly influential feature integration theory
. According to this model, attention binds different features of an object (e.g., color and shape) into consciously experienced wholes. Although this model has received much criticism, it is still widely cited and spawned similar theories with modification, such as Jeremy Wolfe's Guided Search Theory.
In the 1960s, Robert Wurtz at the National Institutes of Health
began recording electrical signals from the brains of macaque
s who were trained to perform attentional tasks. These experiments showed for the first time that there was a direct neural correlate
of a mental process (namely, enhanced firing in the superior colliculus
).
In the 1990s, psychologists began using PET
and later fMRI to image the brain in attentive tasks. Because of the highly expensive equipment that was generally only available in hospitals, psychologists sought for cooperation with neurologists. Pioneers of brain imaging studies of selective attention are psychologist Michael I. Posner
(then already renowned for his seminal work on visual selective attention) and neurologist Marcus Raichle. Their results soon sparked interest from the entire neuroscience community in these psychological studies, which had until then focused on monkey brains. With the development of these technological innovations neuroscientists
became interested in this type of research that combines sophisticated experimental paradigms from cognitive psychology
with these new brain imaging techniques. Although the older technique of EEG
had long been used to study the brain activity underlying selective attention by cognitive psychophysiologists
, the ability of the newer techniques to actually measure precisely localized activity inside the brain generated renewed interest by a wider community of researchers. The results of these experiments have shown a broad agreement with the psychological, psychophysiological and the experiments performed on monkeys.
there are at least two models which describe how visual attention operates. These models may be considered loosely as metaphors which are used to describe internal processes and to generate hypotheses that are falsifiable. Generally speaking, visual attention is thought to operate as a two-stage process. In the first stage, attention is distributed uniformly over the external visual scene and processing of information is performed in parallel. In the second stage, attention is concentrated to a specific area of the visual scene (i.e. it is focused), and processing is performed in a serial fashion.
The first of these models to appear in the literature is the spotlight model. The term "spotlight" was first used by David LaBerge, and was inspired by the work of William James
who described attention as having a focus, a margin, and a fringe. The focus is an area that extracts information from the visual scene with a high-resolution, the geometric center of which being where visual attention is directed. Surrounding the focus is the fringe of attention which extracts information in a much more crude fashion (i.e. low-resolution). This fringe extends out to a specified area and this cut-off is called the margin.
The second model is called the zoom-lens model, and was first introduced in 1983. This model inherits all properties of the spotlight model (i.e. the focus, the fringe, and the margin) but has the added property of changing in size. This size-change mechanism was inspired by the zoom lens
you might find on a camera, and any change in size can be described by a trade-off in the efficiency of processing. The zoom-lens of attention can be described in terms of an inverse trade-off between the size of focus and the efficiency of processing: because attentional resources are assumed to be fixed, then it follows that the larger the focus is, the slower processing will be of that region of the visual scene since this fixed resource will be distributed over a larger area. It is thought that the focus of attention can subtend a minimum of 1° of visual angle
, however the maximum size has not yet been determined.
The first aspect is called bottom-up processing, also known as stimulus-driven attention or exogenous attention. These describe the aspects of our attentional processing that are thought to be driven by the properties of the objects themselves. These aspects of attention are thought to involve parietal
and temporal
cortices, as well as the brainstem. Certain aspects of an object's properties, such as motion or a sudden loud noise, have the capacity to attract our attention in a pre-conscious, or non-volitional way. We attend to them whether we want to or not.
The second aspects is called top-down processing, also known as goal-driven, endogenous attention, attentional control
or executive
attention. This refers to those aspects of our attentional orienting which are under the control of the person who is attending. In the brain, it is thought to be mediated primarily by the frontal
cortex and basal ganglia
.
, also known as endogenous or executive
attention, refers to our capacity to choose what we pay attention to and what we ignore. It is considered one of the executive functions
, mediated primarily by frontal
areas of the brain. Subcomponents of attentional control include conflict resolution and inhibition. Individuals' capacity to exercise attentional control has been shown to relate to other aspects of the executive functions
, such as working memory
.
organs towards a stimulus source. Covert attention is the act of mentally focusing on one of several possible sensory stimuli. Covert attention is thought to be a neural process that enhances the signal from a particular part of the sensory panorama. (e.g. While reading, shifting overt attention would amount to movement of eyes to read different words, but covert attention shift would occur when you shift your focus from semantic processing of word to the font or color of the word you are reading.)
There are studies that suggest the mechanisms of overt and covert attention may not be as separate as previously believed. Though humans and primates can look in one direction but attend in another, there may be an underlying neural circuitry that links shifts in covert attention to plans to shift gaze. For example, if individuals attend to the right hand corner field of view, movement of the eyes in that direction may have to be actively suppressed.
The current view is that visual covert attention is a mechanism for quickly scanning the field of view for interesting locations. This shift in covert attention is linked to eye movement circuitry that sets up a slower saccade
to that location.
Some people can process multiple stimuli, e.g. trained morse code operators have been able to copy 100% of a message while carrying on a meaningful conversation. This relies on the reflexive response due to "overlearning" the skill of morse code reception/detection/transcription so that it is an autonomous function requiring no specific attention to perform.
of attention is enhanced firing. If a neuron has a certain response to a stimulus when the animal is not attending to the stimulus, then when the animal does attend to the stimulus, the neuron's response will be enhanced even if the physical characteristics of the stimulus remain the same.
In a recent review, Knudsen describes a more general model which identifies four core processes of attention, with working memory
at the center:
Neurally, at different hierarchical levels spatial maps can enhance or inhibit activity in sensory areas, and induce orienting behaviors like eye movement.
In many cases attention produces changes in the EEG
. Many animals, including humans, produce gamma waves (40–60 Hz) when focusing attention on a particular object or activity.
Psychology
Psychology is the study of the mind and behavior. Its immediate goal is to understand individuals and groups by both establishing general principles and researching specific cases. For many, the ultimate goal of psychology is to benefit society...
and cognitive neuroscience
Cognitive neuroscience
Cognitive neuroscience is an academic field concerned with the scientific study of biological substrates underlying cognition, with a specific focus on the neural substrates of mental processes. It addresses the questions of how psychological/cognitive functions are produced by the brain...
.
In 1890, William James
William James
William James was a pioneering American psychologist and philosopher who was trained as a physician. He wrote influential books on the young science of psychology, educational psychology, psychology of religious experience and mysticism, and on the philosophy of pragmatism...
, in his textbook Principles of Psychology
Principles of Psychology
The Principles of Psychology is a monumental text in the history of psychology, written by William James and published in 1890.There were four methods in James' psychology: analysis , introspection , experiment The Principles of Psychology is a monumental text in the history of psychology, written...
, remarked:
Attention remains a major area of investigation within education
Education
Education in its broadest, general sense is the means through which the aims and habits of a group of people lives on from one generation to the next. Generally, it occurs through any experience that has a formative effect on the way one thinks, feels, or acts...
, psychology
Psychology
Psychology is the study of the mind and behavior. Its immediate goal is to understand individuals and groups by both establishing general principles and researching specific cases. For many, the ultimate goal of psychology is to benefit society...
and neuroscience
Neuroscience
Neuroscience is the scientific study of the nervous system. Traditionally, neuroscience has been seen as a branch of biology. However, it is currently an interdisciplinary science that collaborates with other fields such as chemistry, computer science, engineering, linguistics, mathematics,...
. Areas of active investigation involve determining the source of the signals that generate attention, the effects of these signals on the tuning
Neuronal tuning
Neuronal tuning refers to the property of brain cells to selectively represent a particular kind of sensory, motor, or cognitive information. For example, an auditory system neuron best responding to the sound of particular frequency is said to be tuned to that frequency. In the visual system,...
properties of sensory neurons, and the relationship between attention and other cognitive processes like working memory
Working memory
Working memory has been defined as the system which actively holds information in the mind to do verbal and nonverbal tasks such as reasoning and comprehension, and to make it available for further information processing...
. Another ongoing line of research involves studying how attention is disrupted early in the development of different disorders, and how abnormalities in the allocation of attention can affect subsequent learning.
1850s to 1900s
In William James' time, the method more commonly used to study attention was introspectionIntrospection
Introspection is the self-observation and reporting of conscious inner thoughts, desires and sensations. It is a conscious and purposive process relying on thinking, reasoning, and examining one's own thoughts, feelings, and, in more spiritual cases, one's soul...
. However, as early as 1858, Franciscus Donders
Franciscus Donders
-External links:* B. Theunissen. , F.C. Donders: turning refracting into science, @ History of science and scholarship in the Netherlands.* in the Virtual Laboratory of the Max Planck Institute for the History of Science* P. Eling, , Geneeskundige en fysioloog....
used mental chronometry
Mental chronometry
Mental chronometry is the use of response time in perceptual-motor tasks to infer the content, duration, and temporal sequencing of cognitive operations....
to study attention and it was considered a major field of intellectual inquiry by authors such as Sigmund Freud
Sigmund Freud
Sigmund Freud , born Sigismund Schlomo Freud , was an Austrian neurologist who founded the discipline of psychoanalysis...
. One major debate in this period was whether it was possible to attend to two things at once (split attention). Walter Benjamin described this experience as "reception in a state of distraction." This disagreement could only be resolved through experimentation.
1950s to present
In the 1950s, research psychologists renewed their interest in attention when the dominant epistemology shifted from positivism (i.e., behaviorism) to realismPhilosophical realism
Contemporary philosophical realism is the belief that our reality, or some aspect of it, is ontologically independent of our conceptual schemes, linguistic practices, beliefs, etc....
during what has come to be known as the "cognitive revolution
Cognitive revolution
The cognitive revolution is the name for an intellectual movement in the 1950s that began what are known collectively as the cognitive sciences. It began in the modern context of greater interdisciplinary communication and research...
". The cognitive revolution admitted unobservable cognitive processes like attention as legitimate objects of scientific study.
Modern research on attention began with the analysis of the "cocktail party problem" by
Colin Cherry
Colin Cherry
Edward Colin Cherry was a British cognitive scientist whose main contributions were in focused auditory attention, specifically regarding the cocktail party problem. This concerns the problem of following only one conversation while many other conversations are going on around us...
in 1953. At a cocktail party how do people select the conversation that they are listening to and ignore the rest? This problem is at times called "focused attention", as opposed to "divided attention". Cherry performed a number of experiments which became known as dichotic listening
Dichotic listening
In cognitive psychology, dichotic listening is a procedure commonly used to investigate selective attention in the auditory system. In dichotic listening, two different auditory stimuli are presented to the participant simultaneously, one to each ear, normally using a set of headphones...
and were extended by Donald Broadbent
Donald Broadbent
Donald Eric Broadbent FRS was an influential English experimental psychologist. His career and his research work bridged the gap between the pre-Second World War approach of Sir Frederic Bartlett and its wartime development into applied psychology, and what from the late 1960s became known as...
and others. In a typical experiment, subjects would use a set of headphones
Headphones
Headphones are a pair of small loudspeakers, or less commonly a single speaker, held close to a user's ears and connected to a signal source such as an audio amplifier, radio, CD player or portable Media Player. They are also known as stereophones, headsets or, colloquially, cans. The in-ear...
to listen to two streams of words in different ears
EARS
EARS may refer to:* Electoral software* Electronic Arts, Redwood Shores campus.* Emirates Amateur Radio Society...
and selectively attend to one stream. After the task, the experimenter would question the subjects about the content of the unattended stream. Experiments by Gray and Wedderburn and later Anne Treisman
Anne Treisman
Anne Marie Treisman FRS is a psychologist currently at Princeton University's Department of Psychology. She researches visual attention, object perception, and memory. One of her most influential ideas is the feature integration theory of attention, first published with G. Gelade in 1980...
pointed out various problems in Broadbent's early model and eventually led to the Deutsch-Norman model in 1968. In this model, no signal is filtered out, but all are processed to the point of activating their stored representations in memory. The point at which attention becomes "selective" is when one of the memory representations is selected for further processing. At any time, only one can be selected, resulting in the attentional bottleneck.
This debate became known as the early-selection vs late-selection models. In the early selection models (first proposed by Donald Broadbent
Donald Broadbent
Donald Eric Broadbent FRS was an influential English experimental psychologist. His career and his research work bridged the gap between the pre-Second World War approach of Sir Frederic Bartlett and its wartime development into applied psychology, and what from the late 1960s became known as...
and Anne Treisman
Anne Treisman
Anne Marie Treisman FRS is a psychologist currently at Princeton University's Department of Psychology. She researches visual attention, object perception, and memory. One of her most influential ideas is the feature integration theory of attention, first published with G. Gelade in 1980...
), attention shuts down or attenuates processing in the unattended ear before the mind can analyze its semantic content. In the late selection models (first proposed by J. Anthony Deutsch and Diana Deutsch
Diana Deutsch
Diana Deutsch is a British-American perceptual and cognitive psychologist, born in London, England. She is currently Professor of Psychology at the University of California, San Diego, and is one of the most prominent researchers on the psychology of music...
), the content in both ears is analyzed semantically, but the words in the unattended ear cannot access consciousness. This debate has still not been resolved.
Anne Treisman
Anne Treisman
Anne Marie Treisman FRS is a psychologist currently at Princeton University's Department of Psychology. She researches visual attention, object perception, and memory. One of her most influential ideas is the feature integration theory of attention, first published with G. Gelade in 1980...
developed the highly influential feature integration theory
Feature integration theory
The feature integration theory, developed by Anne Treisman and Garry Gelade since the early 1980s, posits that different kinds of attention are responsible for binding different features into consciously experienced wholes...
. According to this model, attention binds different features of an object (e.g., color and shape) into consciously experienced wholes. Although this model has received much criticism, it is still widely cited and spawned similar theories with modification, such as Jeremy Wolfe's Guided Search Theory.
In the 1960s, Robert Wurtz at the National Institutes of Health
National Institutes of Health
The National Institutes of Health are an agency of the United States Department of Health and Human Services and are the primary agency of the United States government responsible for biomedical and health-related research. Its science and engineering counterpart is the National Science Foundation...
began recording electrical signals from the brains of macaque
Macaque
The macaques constitute a genus of Old World monkeys of the subfamily Cercopithecinae. - Description :Aside from humans , the macaques are the most widespread primate genus, ranging from Japan to Afghanistan and, in the case of the barbary macaque, to North Africa...
s who were trained to perform attentional tasks. These experiments showed for the first time that there was a direct neural correlate
Neural correlate
A neural correlate of a content of experience is any bodily component, such as an electro-neuro-biological state or the state assumed by some biophysical subsystem of the brain, whose presence necessarily and regularly correlates with such a specific content of experience.When the full ontological...
of a mental process (namely, enhanced firing in the superior colliculus
Superior colliculus
The optic tectum or simply tectum is a paired structure that forms a major component of the vertebrate midbrain. In mammals this structure is more commonly called the superior colliculus , but, even in mammals, the adjective tectal is commonly used. The tectum is a layered structure, with a...
).
In the 1990s, psychologists began using PET
Positron emission tomography
Positron emission tomography is nuclear medicine imaging technique that produces a three-dimensional image or picture of functional processes in the body. The system detects pairs of gamma rays emitted indirectly by a positron-emitting radionuclide , which is introduced into the body on a...
and later fMRI to image the brain in attentive tasks. Because of the highly expensive equipment that was generally only available in hospitals, psychologists sought for cooperation with neurologists. Pioneers of brain imaging studies of selective attention are psychologist Michael I. Posner
Michael Posner (psychologist)
Michael I. Posner is the editor of numerous cognitive and neuroscience compilations and is an eminent researcher in the field of attention...
(then already renowned for his seminal work on visual selective attention) and neurologist Marcus Raichle. Their results soon sparked interest from the entire neuroscience community in these psychological studies, which had until then focused on monkey brains. With the development of these technological innovations neuroscientists
Neuroscience
Neuroscience is the scientific study of the nervous system. Traditionally, neuroscience has been seen as a branch of biology. However, it is currently an interdisciplinary science that collaborates with other fields such as chemistry, computer science, engineering, linguistics, mathematics,...
became interested in this type of research that combines sophisticated experimental paradigms from cognitive psychology
Cognitive psychology
Cognitive psychology is a subdiscipline of psychology exploring internal mental processes.It is the study of how people perceive, remember, think, speak, and solve problems.Cognitive psychology differs from previous psychological approaches in two key ways....
with these new brain imaging techniques. Although the older technique of EEG
EEG
EEG commonly refers to electroencephalography, a measurement of the electrical activity of the brain.EEG may also refer to:* Emperor Entertainment Group, a Hong Kong-based entertainment company...
had long been used to study the brain activity underlying selective attention by cognitive psychophysiologists
Psychophysiology
Psychophysiology is the branch of psychology that is concerned with the physiological bases of psychological processes. While psychophysiology was a general broad field of research in the 1960s and 1970s, it has now become quite specialized, and has branched into subspecializations...
, the ability of the newer techniques to actually measure precisely localized activity inside the brain generated renewed interest by a wider community of researchers. The results of these experiments have shown a broad agreement with the psychological, psychophysiological and the experiments performed on monkeys.
Selective Attention
In cognitive psychologyCognitive psychology
Cognitive psychology is a subdiscipline of psychology exploring internal mental processes.It is the study of how people perceive, remember, think, speak, and solve problems.Cognitive psychology differs from previous psychological approaches in two key ways....
there are at least two models which describe how visual attention operates. These models may be considered loosely as metaphors which are used to describe internal processes and to generate hypotheses that are falsifiable. Generally speaking, visual attention is thought to operate as a two-stage process. In the first stage, attention is distributed uniformly over the external visual scene and processing of information is performed in parallel. In the second stage, attention is concentrated to a specific area of the visual scene (i.e. it is focused), and processing is performed in a serial fashion.
The first of these models to appear in the literature is the spotlight model. The term "spotlight" was first used by David LaBerge, and was inspired by the work of William James
William James
William James was a pioneering American psychologist and philosopher who was trained as a physician. He wrote influential books on the young science of psychology, educational psychology, psychology of religious experience and mysticism, and on the philosophy of pragmatism...
who described attention as having a focus, a margin, and a fringe. The focus is an area that extracts information from the visual scene with a high-resolution, the geometric center of which being where visual attention is directed. Surrounding the focus is the fringe of attention which extracts information in a much more crude fashion (i.e. low-resolution). This fringe extends out to a specified area and this cut-off is called the margin.
The second model is called the zoom-lens model, and was first introduced in 1983. This model inherits all properties of the spotlight model (i.e. the focus, the fringe, and the margin) but has the added property of changing in size. This size-change mechanism was inspired by the zoom lens
Zoom lens
A zoom lens is a mechanical assembly of lens elements for which the focal length can be varied, as opposed to a fixed focal length lens...
you might find on a camera, and any change in size can be described by a trade-off in the efficiency of processing. The zoom-lens of attention can be described in terms of an inverse trade-off between the size of focus and the efficiency of processing: because attentional resources are assumed to be fixed, then it follows that the larger the focus is, the slower processing will be of that region of the visual scene since this fixed resource will be distributed over a larger area. It is thought that the focus of attention can subtend a minimum of 1° of visual angle
Visual angle
The visual angle is the angle a viewed object subtends at the eye, usually stated in degrees of arc.It also is called the object's angular size....
, however the maximum size has not yet been determined.
Bottom-Up vs Top-Down
Attention Researchers have described two different aspects of how our minds select items present in the environment to attend to.The first aspect is called bottom-up processing, also known as stimulus-driven attention or exogenous attention. These describe the aspects of our attentional processing that are thought to be driven by the properties of the objects themselves. These aspects of attention are thought to involve parietal
Parietal lobe
The parietal lobe is a part of the Brain positioned above the occipital lobe and behind the frontal lobe.The parietal lobe integrates sensory information from different modalities, particularly determining spatial sense and navigation. For example, it comprises somatosensory cortex and the...
and temporal
Temporal lobe
The temporal lobe is a region of the cerebral cortex that is located beneath the Sylvian fissure on both cerebral hemispheres of the mammalian brain....
cortices, as well as the brainstem. Certain aspects of an object's properties, such as motion or a sudden loud noise, have the capacity to attract our attention in a pre-conscious, or non-volitional way. We attend to them whether we want to or not.
The second aspects is called top-down processing, also known as goal-driven, endogenous attention, attentional control
Attentional Control
In cognitive neuroscience, attentional control refers to individuals' capacity to choose what they pay attention to and what they ignore. It is also known as endogenous attention or executive attention. In lay terms, attentional control can be described as an individual's ability to concentrate...
or executive
Executive functions
The executive system is a theorized cognitive system in psychology that controls and manages other cognitive processes. It is responsible for processes that are sometimes referred to as the executive function, executive functions, supervisory attentional system, or cognitive control...
attention. This refers to those aspects of our attentional orienting which are under the control of the person who is attending. In the brain, it is thought to be mediated primarily by the frontal
Frontal lobe
The frontal lobe is an area in the brain of humans and other mammals, located at the front of each cerebral hemisphere and positioned anterior to the parietal lobe and superior and anterior to the temporal lobes...
cortex and basal ganglia
Basal ganglia
The basal ganglia are a group of nuclei of varied origin in the brains of vertebrates that act as a cohesive functional unit. They are situated at the base of the forebrain and are strongly connected with the cerebral cortex, thalamus and other brain areas...
.
Attentional Control/Executive Attention
Attentional controlAttentional Control
In cognitive neuroscience, attentional control refers to individuals' capacity to choose what they pay attention to and what they ignore. It is also known as endogenous attention or executive attention. In lay terms, attentional control can be described as an individual's ability to concentrate...
, also known as endogenous or executive
Executive functions
The executive system is a theorized cognitive system in psychology that controls and manages other cognitive processes. It is responsible for processes that are sometimes referred to as the executive function, executive functions, supervisory attentional system, or cognitive control...
attention, refers to our capacity to choose what we pay attention to and what we ignore. It is considered one of the executive functions
Executive functions
The executive system is a theorized cognitive system in psychology that controls and manages other cognitive processes. It is responsible for processes that are sometimes referred to as the executive function, executive functions, supervisory attentional system, or cognitive control...
, mediated primarily by frontal
Frontal lobe
The frontal lobe is an area in the brain of humans and other mammals, located at the front of each cerebral hemisphere and positioned anterior to the parietal lobe and superior and anterior to the temporal lobes...
areas of the brain. Subcomponents of attentional control include conflict resolution and inhibition. Individuals' capacity to exercise attentional control has been shown to relate to other aspects of the executive functions
Executive functions
The executive system is a theorized cognitive system in psychology that controls and manages other cognitive processes. It is responsible for processes that are sometimes referred to as the executive function, executive functions, supervisory attentional system, or cognitive control...
, such as working memory
Working memory
Working memory has been defined as the system which actively holds information in the mind to do verbal and nonverbal tasks such as reasoning and comprehension, and to make it available for further information processing...
.
Overt and covert attention
Attention may be differentiated according to its status as "overt" versus "covert". Overt attention is the act of directing senseSense
Senses are physiological capacities of organisms that provide inputs for perception. The senses and their operation, classification, and theory are overlapping topics studied by a variety of fields, most notably neuroscience, cognitive psychology , and philosophy of perception...
organs towards a stimulus source. Covert attention is the act of mentally focusing on one of several possible sensory stimuli. Covert attention is thought to be a neural process that enhances the signal from a particular part of the sensory panorama. (e.g. While reading, shifting overt attention would amount to movement of eyes to read different words, but covert attention shift would occur when you shift your focus from semantic processing of word to the font or color of the word you are reading.)
There are studies that suggest the mechanisms of overt and covert attention may not be as separate as previously believed. Though humans and primates can look in one direction but attend in another, there may be an underlying neural circuitry that links shifts in covert attention to plans to shift gaze. For example, if individuals attend to the right hand corner field of view, movement of the eyes in that direction may have to be actively suppressed.
The current view is that visual covert attention is a mechanism for quickly scanning the field of view for interesting locations. This shift in covert attention is linked to eye movement circuitry that sets up a slower saccade
Saccade
A saccade is a fast movement of an eye, head or other part of an animal's body or device. It can also be a fast shift in frequency of an emitted signal or other quick change. Saccades are quick, simultaneous movements of both eyes in the same direction...
to that location.
Influence of Processing Load
One theory regarding selective attention is the load theory, which states that there are two mechanisms that affect attention: cognitive and perceptual. The perceptual considers the subject’s ability to perceive or ignore stimuli, both task-related and non task-related. Studies show that if there are many stimuli present (especially if they are task-related), it is much easier to ignore the non-task related stimuli, but if there are few stimuli the mind will perceive the irrelevant stimuli as well as the relevant. The cognitive refers to the actual processing of the stimuli, studies regarding this showed that the ability to process stimuli decreased with age, meaning that younger people were able to perceive more stimuli and fully process them, but were likely to process both relevant and irrelevant information, while older people could process fewer stimuli, but usually processed only relevant information.Some people can process multiple stimuli, e.g. trained morse code operators have been able to copy 100% of a message while carrying on a meaningful conversation. This relies on the reflexive response due to "overlearning" the skill of morse code reception/detection/transcription so that it is an autonomous function requiring no specific attention to perform.
Neural correlates of attention
Most experiments show that one neural correlateNeural correlate
A neural correlate of a content of experience is any bodily component, such as an electro-neuro-biological state or the state assumed by some biophysical subsystem of the brain, whose presence necessarily and regularly correlates with such a specific content of experience.When the full ontological...
of attention is enhanced firing. If a neuron has a certain response to a stimulus when the animal is not attending to the stimulus, then when the animal does attend to the stimulus, the neuron's response will be enhanced even if the physical characteristics of the stimulus remain the same.
In a recent review, Knudsen describes a more general model which identifies four core processes of attention, with working memory
Working memory
Working memory has been defined as the system which actively holds information in the mind to do verbal and nonverbal tasks such as reasoning and comprehension, and to make it available for further information processing...
at the center:
- Working memoryWorking memoryWorking memory has been defined as the system which actively holds information in the mind to do verbal and nonverbal tasks such as reasoning and comprehension, and to make it available for further information processing...
temporarily stores information for detailed analysis. - Competitive selection is the process that determines which information gains access to working memory.
- Through top-down sensitivity control, higher cognitive processes can regulate signal intensity in information channels that compete for access to working memory, and thus give them an advantage in the process of competitive selection. Through top-down sensitivity control, the momentary content of working memory can influence the selection of new information, and thus mediate voluntary control of attention in a recurrent loop (endogenous attention).
- Bottom-up saliency filters automatically enhance the response to infrequent stimuli, or stimuli of instinctive or learned biological relevance (exogenous attention).
Neurally, at different hierarchical levels spatial maps can enhance or inhibit activity in sensory areas, and induce orienting behaviors like eye movement.
- At the top of the hierarchy, the frontal eye fieldsFrontal eye fieldsThe frontal eye fields is a region located in the premotor cortex, which is part of the frontal cortex of the primate brain.-Function:...
(FEF) on the dorsolateral frontal cortex contain a retinocentric spatial map. Microstimulation in the FEF induces monkeys to make a saccadeSaccadeA saccade is a fast movement of an eye, head or other part of an animal's body or device. It can also be a fast shift in frequency of an emitted signal or other quick change. Saccades are quick, simultaneous movements of both eyes in the same direction...
to the relevant location. Stimulation at levels too low to induce a saccade will nonetheless enhance cortical responses to stimuli located in the relevant area. - At the next lower level, a variety of spatial maps are found in the parietal cortex. In particular, the lateral intraparietal area (LIP) contains a saliency map and is interconnected both with the FEF and with sensory areas.
- Certain automatic responses that influence attention, like orienting to a highly salient stimulus, are mediated subcortically by the superior colliculi.
- At the neural network level, it is thought that processes like lateral inhibition mediate the process of competitive selection.
In many cases attention produces changes in the EEG
EEG
EEG commonly refers to electroencephalography, a measurement of the electrical activity of the brain.EEG may also refer to:* Emperor Entertainment Group, a Hong Kong-based entertainment company...
. Many animals, including humans, produce gamma waves (40–60 Hz) when focusing attention on a particular object or activity.