Increase Focus
Attention
is the cognitive process of selectively concentrating on one aspect of the
environment while ignoring other things. Attention has also been referred to as
the allocation of processing resources. Attention is one of the most intensely
studied topics within psychology and cognitive neuroscience. 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 and vigilance. A relatively new body of research
is investigating the phenomenon of traumatic brain injuries and their effects on
attention. Attention also has variations amongst
cultures.
History
of the study of attention
Philosophical period
Prior to the
founding of psychology as a scientific discipline, attention was studied in the
field of philosophy. Due to this, many of the discoveries in the field of
Attention were made by philosophers. Psychologist John Watson cites Juan Luis
Vives as the Father of Modern Psychology due to his book De Anima et Vita in
which Vives was the first to recognize the importance of empirical
investigation. In his work on memory, Vives found that the more closely one
attends to stimuli, the better they will be retained.
Psychologist
Daniel E. Berlyne credits the first extended treatment of attention to
philosopher Nicolas Malebranche in his work "The Search After Truth".
"Malebranche held that we have access to ideas, or mental representations of the
external world, but not direct access to the world itself." Thus in order
to keep these ideas organized, attention is necessary. Otherwise we will confuse
these ideas. Malebranche writes in "The Search After Truth", "because it often
happens that the understanding has only confused and imperfect perceptions of
things, it is truly a cause of our errors.... It is therefore necessary to look
for means to keep our perceptions from being confused and imperfect. And,
because, as everyone knows, there is nothing that makes them clearer and more
distinct than attentiveness, we must try to find the means to become more
attentive than we are". According to Malebranche, attention is crucial to
understanding and keeping thoughts organized.
Philosopher
Gottfried Wilhelm Leibniz introduced the concept of apperception to this
philosophical approach to attention. Apperception refers to "the process by
which new experience is assimilated to and transformed by the residuum of past
experience of an individual to form a new whole." Apperception is required
for a perceived event to become a conscious event. Leibniz emphasized a
reflexive involuntary view of attention known as exogenous orienting. However
there is also endogenous orienting which is voluntary and directed attention.
Philosopher Johann Friedrich Herbart agreed with Leibniz's view of apperception
however he expounded on it in by saying that new experiences had to be tied to
ones already existing in the mind. Herbart was also the first person to stress
the importance of applying mathematical modeling to the study of
psychology.
It was
previously thought in the beginning of the 19th century that people were not
able to attend to more than one stimulus at a time. However with research
contributions by Sir William Hamilton, 9th Baronet this view was changed.
Hamilton proposed a view of attention that likened its capacity to holding
marbles. You can only hold a certain amount of marbles at a time before it
starts to spill over. His view states that we can attend to more than one
stimulus at once. William Stanley Jevons later expanded this view and stated
that we can attend to up to four items at a time.
During this
period of attention, various philosophers made significant contributions to the
field. They began the research on the extent of attention and how attention is
directed.
1860-1909
This period
of attention research took the focus from conceptual findings to experimental
testing. It also involved psychophysical methods that allowed measurement of the
relation between physical stimulus properties and the psychological perceptions
of them. This period covers the development of attentional research from the
founding of psychology to 1909.
Wilhelm
Wundt introduced the study of attention to the field of psychology. Wundt
measured mental processing speed by likening it to differences in stargazing
measurements. Astronomer's in this time would measure the time it took for stars
to travel. Among these measurements when astronomers recorded the times, there
were personal differences in calculation. These different readings resulted in
different reports from each astronomer. To correct for this, a personal equation
was developed. Wundt applied this to mental processing speed. Wundt realized
that the time it takes to see the stimulus of the star and write down the time
was being called an "observation error" but actually was the time it takes to
switch voluntarily one's attention from one stimulus to another. Wundt called
his school of psychology voluntarism. It was his belief that psychological
processes can only be understood in terms of goals and
consequences.
Franciscus
Donders used mental chronometry to study attention and it was considered a major
field of intellectual inquiry by authors such as Sigmund Freud. Donders and his
students conducted the first detailed investigations of the speed of mental
processes. Donders measured the time required to identify a stimulus and to
select a motor response. This was the time difference between stimulus
discrimination and response initiation. Donders also formalized the subtractive
method which states that the time for a particular process can be estimated by
adding that process to a task and taking the difference in reaction time between
the two tasks. He also differentiated between three types of reactions: simple
reaction, choice reaction, and go/no-go reaction.
Hermann von
Helmholtz also contributed to the field of attention relating to the extent of
attention. Von Helmholtz stated that it is possible to focus on one stimulus and
still perceive or ignore others. An example of this is being able to focus on
the letter u in the word house and still perceiving the letters h, o, s, and
e.
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.
In 1890,
William James, in his textbook Principles of Psychology,
remarked:
“ Everyone
knows what attention is. It is the taking possession by the mind, in clear and
vivid form, of one out of what seem several simultaneously possible objects or
trains of thought. Focalization, concentration, of consciousness are of its
essence. It implies withdrawal from some things in order to deal effectively
with others, and is a condition which has a real opposite in the confused,
dazed, scatterbrained state which in French is called distraction, and
Zerstreutheit in German. ”
James
differentiated between sensorial attention and intellectual attention. Sensorial
attention is when attention is directed to objects of sense, stimuli that are
physically present. Intellectual attention is attention directed to ideal or
represented objects; stimuli that are not physically present. James also
distinguished between immediate or derived attention: attention to the present
versus to something not physically present. According to James, attention has
five major effects. Attention works to make us perceive, conceive, distinguish,
remember, and shorten reactions time.
1910-1949
During the
period from 1910-1949, research in attention waned and interest in behaviorism
flourished. It is often stated that there was no research during this period.
Ulric Neisser stated that in this period, "There was no research on attention".
This is simply not true. In 1927 Jersild published very important work on
"Mental Set and Shift". He stated, "The fact of mental set is primary in all
conscious activity. The same stimulus may evoke any one of a large number of
responses depending upon the contextual setting in which it is placed". This
research found that the time to complete a list was longer for mixed lists than
for pure lists. For example, if a list was names of animals versus a list with
names of animals, books, makes and models of cars, and types of fruits, it takes
longer to process. This is task switching.
In 1931,
Telford discovered the psychological refractory period. The stimulation of
neurons is followed by a refractory phase during which neurons are less
sensitive to stimulation. In 1935 John Ridley Stroop developed the Stroop Task
which elicited the Stroop Effect. Stroop's task showed that irrelevant stimulus
information can have a major impact on performance. In this task, subjects were
to look at a list of colors. This list of colors had each color typed in a color
different from the actual text. For example the word Blue would be typed in
Orange, Pink in Black, etc.
Example:
Blue Purple Red Green Purple Green
Subjects
were then instructed to say the name of the ink color and ignore the text. It
took 110 seconds to complete a list of this type compared to 63 seconds to name
the colors when presented in the form of solid squares. The naming time nearly
doubled in the presence of conflicting color words, an effect known as the
Stroop Effect.
1950-1974
In the
1950s, research psychologists renewed their interest in attention when the
dominant epistemology shifted from positivism (i.e., behaviorism) to realism
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.
Broadbent's
Filter Model of Attention states that information is held in a pre-attentive
temporary store, and only sensory events that have some physical feature in
common are selected to pass into the limited capacity processing system. This
implies that the meaning of unattended messages is not identified. Also, a
significant amount of time is required to shift the filter from one channel to
another. 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), attention shuts down (in
Broadbent's model) or attenuates (in Triesman's refinement) 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.
In the
1960s, Robert Wurtz at the National Institutes of Health began recording
electrical signals from the brains of macaques 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
mid-1970s, multiple resource models were put forth. These studies showed that it
is easier to perform two tasks together when the tasks use different stimulus or
response modalities than when they use the same modalities. Michael Posner did
research on space-based versus object-based approaches to attention in the
1980s. For space-based attention, attention is likened to that of a spotlight.
Attention is directed to everything in the spotlight's
field.
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
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.[citation needed]
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
Selective
attention
The spotlight model of attention.
Visual attention
In cognitive
psychology 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 inspired by the work of William James who described attention as
having a focus, a margin, and a fringe.[16] 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 that 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.
Auditory
Attention
Selective
Auditory Attention
Divided
attention
Divided
attention is the task of actively paying attention to more than one task at a
time, and it is both important and common in every day life. It is rare for
someone to be engaged in just one task.
Divided
attention can be improved with practice. Spelke, Hirst, and Niesser (1976)
studied accuracy and response time of performance by participants reading short
stories and writing down dictated words. The participants’ initial performance
was very poor when both tasks were performed simultaneously, but after
participants practiced the tasks 5 days a week for 85 sessions, their
performance improved for both tasks (Sternberg & Sternberg, 2012). Spelke
and others have proposed that it is possible that controlled tasks can be
automatized, thus using fewer attentional resources. In addition, how well
people divide their attention has to do with that person's intelligence (Hunt
& Lansman, 1982, as cited in Sternberg & Sternberg, 2012). According to
researchers, more intelligent people can timeshare between two tasks and
effectively perform two tasks better.
There have
been multiple theories regarding divided attention. One, conceived by Kahneman
in 1973, explains that there is a single pool of attentional resources that can
be freely divided among multiple tasks. This model seems to be too
oversimplified, however, due to the different modalities (e.g., visual,
auditory, verbal) that we perceive (Sternberg & Sternberg, 2012). When the
two tasks are from the same modality, such as listening to a radio station and
writing a paper, it is much more difficult to concentrate on both because the
tasks are likely to interfere with each other. The specific modality model was
theorized by Navon and Gopher in 1979. Although this model is more adequate at
explaining divided attention among simple tasks, resource theory is another,
more accurate metaphor for explaining divided attention on complex tasks.
Resource theory demonstrates that as we automatize each complex task, performing
that task requires less of our limited-capacity attentional resources (Sternberg
& Sternberg, 2012).
Other
variables play a part in our ability to pay attention to and concentrate on many
tasks at once. These include, but are not limited to, anxiety, arousal, task
difficulty, and skills (Sternberg & Sternberg, 2012). Attention is a very
multi-faceted process and it is better understood now due to cognitive research
and the study of the brain.
Bottom-Up vs
Top-Down
Researchers
have described two different aspects of how our minds come to attend to items
present in the environment.
The first
aspect is called bottom-up processing, also known as stimulus-driven attention
or exogenous attention. These describe attentional processing which is driven by
the properties of the objects themselves. Some processes, such as motion or a
sudden loud noise, can attract our attention in a pre-conscious, or
non-volitional way. We attend to them whether we want to or not. These aspects
of attention are thought to involve parietal and temporal cortices, as well as
the brainstem.
The second
aspect is called top-down processing, also known as goal-driven, endogenous
attention, attentional control or executive attention. This aspect of our
attentional orienting is under the control of the person who is attending. It is
mediated primarily by the frontal cortex and basal ganglia as one of the
executive functions. Research has shown that it is related to other aspects of
the executive functions, such as working memory and conflict resolution and
inhibition.
Overt and
covert attention
Attention
may be differentiated according to its status as "overt" versus "covert". Overt
attention is the act of directing sense 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 a 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.
Influence of
processing load
One theory
regarding selective attention is the cognitive 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.
Clinical
model of attention
Attention is
best described as the sustained focus of cognitive resources on information
while filtering or ignoring extraneous information. Attention is a very basic
function that often is a precursor to all other neurological/cognitive
functions. As is frequently the case, clinical models of attention differ from
investigation models. One of the most used models for the evaluation of
attention in patients with very different neurologic pathologies is the model of
Sohlberg and Mateer. This hierarchic model is based in the recovering of
attention processes of brain damage patients after coma. Five different kinds of
activities of growing difficulty are described in the model; connecting with the
activities those patients could do as their recovering process
advanced.
Focused attention: The ability to respond discretely to specific
visual, auditory or tactile stimuli.
Sustained attention (vigilance): The
ability to maintain a consistent behavioral response during continuous and
repetitive activity.
Selective attention: The ability to maintain a
behavioral or cognitive set in the face of distracting or competing stimuli.
Therefore it incorporates the notion of "freedom from
distractibility."
Alternating attention: The ability of mental flexibility
that allows individuals to shift their focus of attention and move between tasks
having different cognitive requirements.
Divided attention: This is the
highest level of attention and it refers to the ability to respond
simultaneously to multiple tasks or multiple task
demands.
This model
has been shown to be very useful in evaluating attention in very different
pathologies, correlates strongly with daily difficulties and is especially
helpful in designing stimulation programs such as attention process training, a
rehabilitation program for neurologic patients of the same
authors.
Neural
correlates of attention
Most
experiments show that one neural correlate 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:
Working
memory 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).
Neutrally,
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 fields (FEF) on the dorsolateral frontal
cortex contain a retinocentric spatial map. Microstimulation in the FEF induces
monkeys to make a saccade 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. Many animals, including humans,
produce gamma waves (40–60 Hz) when focusing attention on a particular object or
activity.
Another
commonly used model for the attention system has been put forth by researchers
such as Michael Posner divides attention into three functional components:
alerting, orienting, and executive attention.
Alerting is the process
involved in becoming and staying attentive toward the surroundings. It appears
to exist in the frontal and parietal lobes of the right hemisphere, and is
modulated by norepinephrine.
Orienting is the directing of attention to a
specific stimulus.
Executive attention is used when there is a conflict
between multiple attention cues. It is essentially the same as the central
executive in Baddeley's model of working memory. The Eriksen flanker task has
shown that the executive control of attention may take place in the anterior
cingulate cortex
Cultural
variation
Children
appear to develop patterns of attention related to the cultural practices of
their families, communities, and the institutions in which they
participate.
In 1955
Henry suggested that there are societal differences in sensitivity to signals
from many ongoing sources that call for the awareness of several levels of
attention simultaneously. He tied his speculation to ethnographic observations
of communities in which children are involved in a complex social community with
multiple relationships.
Attention
can be focused in skilled ways on more than one activity at a time, which can be
seen in different communities and cultures such as the Mayans of San Pedro. One
example is simultaneous attention which involves uninterrupted attention to
several activities occurring at the same time. Another cultural practice that
may relate to simultaneous attention strategies is coordination within a group.
San Pedro toddlers and caregivers frequently coordinated their activities with
other members of a group in multiway engagements rather than in a dyadic
fashion.
Attention
modelling
In the
domain of computer vision, efforts have been made in modelling the mechanism of
human attention, especially the bottom-up attentional
mechanism.
Generally
speaking, there are two kinds of models to mimic the bottom-up saliency
mechanism. One way is based on the spatial contrast analysis. For example, in a
center-surround mechanism is used to define saliency across scales, which is
inspired by the putative neural mechanism. It has also been hypothesized that
some visual inputs are intrinsically salient in certain background contexts and
that these are actually task-independent. This model has established itself as
the exemplar for saliency detection and consistently used for comparison in the
literature.; the other way is based on the frequency domain analysis. This
method was first proposed by Hou et al., this method was called SR, and then
PQFT method was also introduced. Both SR and PQFT only use the phase
information. In 2012, the HFT method was introduced, and both the amplitude and
the phase information are made use
of.
is the cognitive process of selectively concentrating on one aspect of the
environment while ignoring other things. Attention has also been referred to as
the allocation of processing resources. Attention is one of the most intensely
studied topics within psychology and cognitive neuroscience. 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 and vigilance. A relatively new body of research
is investigating the phenomenon of traumatic brain injuries and their effects on
attention. Attention also has variations amongst
cultures.
History
of the study of attention
Philosophical period
Prior to the
founding of psychology as a scientific discipline, attention was studied in the
field of philosophy. Due to this, many of the discoveries in the field of
Attention were made by philosophers. Psychologist John Watson cites Juan Luis
Vives as the Father of Modern Psychology due to his book De Anima et Vita in
which Vives was the first to recognize the importance of empirical
investigation. In his work on memory, Vives found that the more closely one
attends to stimuli, the better they will be retained.
Psychologist
Daniel E. Berlyne credits the first extended treatment of attention to
philosopher Nicolas Malebranche in his work "The Search After Truth".
"Malebranche held that we have access to ideas, or mental representations of the
external world, but not direct access to the world itself." Thus in order
to keep these ideas organized, attention is necessary. Otherwise we will confuse
these ideas. Malebranche writes in "The Search After Truth", "because it often
happens that the understanding has only confused and imperfect perceptions of
things, it is truly a cause of our errors.... It is therefore necessary to look
for means to keep our perceptions from being confused and imperfect. And,
because, as everyone knows, there is nothing that makes them clearer and more
distinct than attentiveness, we must try to find the means to become more
attentive than we are". According to Malebranche, attention is crucial to
understanding and keeping thoughts organized.
Philosopher
Gottfried Wilhelm Leibniz introduced the concept of apperception to this
philosophical approach to attention. Apperception refers to "the process by
which new experience is assimilated to and transformed by the residuum of past
experience of an individual to form a new whole." Apperception is required
for a perceived event to become a conscious event. Leibniz emphasized a
reflexive involuntary view of attention known as exogenous orienting. However
there is also endogenous orienting which is voluntary and directed attention.
Philosopher Johann Friedrich Herbart agreed with Leibniz's view of apperception
however he expounded on it in by saying that new experiences had to be tied to
ones already existing in the mind. Herbart was also the first person to stress
the importance of applying mathematical modeling to the study of
psychology.
It was
previously thought in the beginning of the 19th century that people were not
able to attend to more than one stimulus at a time. However with research
contributions by Sir William Hamilton, 9th Baronet this view was changed.
Hamilton proposed a view of attention that likened its capacity to holding
marbles. You can only hold a certain amount of marbles at a time before it
starts to spill over. His view states that we can attend to more than one
stimulus at once. William Stanley Jevons later expanded this view and stated
that we can attend to up to four items at a time.
During this
period of attention, various philosophers made significant contributions to the
field. They began the research on the extent of attention and how attention is
directed.
1860-1909
This period
of attention research took the focus from conceptual findings to experimental
testing. It also involved psychophysical methods that allowed measurement of the
relation between physical stimulus properties and the psychological perceptions
of them. This period covers the development of attentional research from the
founding of psychology to 1909.
Wilhelm
Wundt introduced the study of attention to the field of psychology. Wundt
measured mental processing speed by likening it to differences in stargazing
measurements. Astronomer's in this time would measure the time it took for stars
to travel. Among these measurements when astronomers recorded the times, there
were personal differences in calculation. These different readings resulted in
different reports from each astronomer. To correct for this, a personal equation
was developed. Wundt applied this to mental processing speed. Wundt realized
that the time it takes to see the stimulus of the star and write down the time
was being called an "observation error" but actually was the time it takes to
switch voluntarily one's attention from one stimulus to another. Wundt called
his school of psychology voluntarism. It was his belief that psychological
processes can only be understood in terms of goals and
consequences.
Franciscus
Donders used mental chronometry to study attention and it was considered a major
field of intellectual inquiry by authors such as Sigmund Freud. Donders and his
students conducted the first detailed investigations of the speed of mental
processes. Donders measured the time required to identify a stimulus and to
select a motor response. This was the time difference between stimulus
discrimination and response initiation. Donders also formalized the subtractive
method which states that the time for a particular process can be estimated by
adding that process to a task and taking the difference in reaction time between
the two tasks. He also differentiated between three types of reactions: simple
reaction, choice reaction, and go/no-go reaction.
Hermann von
Helmholtz also contributed to the field of attention relating to the extent of
attention. Von Helmholtz stated that it is possible to focus on one stimulus and
still perceive or ignore others. An example of this is being able to focus on
the letter u in the word house and still perceiving the letters h, o, s, and
e.
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.
In 1890,
William James, in his textbook Principles of Psychology,
remarked:
“ Everyone
knows what attention is. It is the taking possession by the mind, in clear and
vivid form, of one out of what seem several simultaneously possible objects or
trains of thought. Focalization, concentration, of consciousness are of its
essence. It implies withdrawal from some things in order to deal effectively
with others, and is a condition which has a real opposite in the confused,
dazed, scatterbrained state which in French is called distraction, and
Zerstreutheit in German. ”
James
differentiated between sensorial attention and intellectual attention. Sensorial
attention is when attention is directed to objects of sense, stimuli that are
physically present. Intellectual attention is attention directed to ideal or
represented objects; stimuli that are not physically present. James also
distinguished between immediate or derived attention: attention to the present
versus to something not physically present. According to James, attention has
five major effects. Attention works to make us perceive, conceive, distinguish,
remember, and shorten reactions time.
1910-1949
During the
period from 1910-1949, research in attention waned and interest in behaviorism
flourished. It is often stated that there was no research during this period.
Ulric Neisser stated that in this period, "There was no research on attention".
This is simply not true. In 1927 Jersild published very important work on
"Mental Set and Shift". He stated, "The fact of mental set is primary in all
conscious activity. The same stimulus may evoke any one of a large number of
responses depending upon the contextual setting in which it is placed". This
research found that the time to complete a list was longer for mixed lists than
for pure lists. For example, if a list was names of animals versus a list with
names of animals, books, makes and models of cars, and types of fruits, it takes
longer to process. This is task switching.
In 1931,
Telford discovered the psychological refractory period. The stimulation of
neurons is followed by a refractory phase during which neurons are less
sensitive to stimulation. In 1935 John Ridley Stroop developed the Stroop Task
which elicited the Stroop Effect. Stroop's task showed that irrelevant stimulus
information can have a major impact on performance. In this task, subjects were
to look at a list of colors. This list of colors had each color typed in a color
different from the actual text. For example the word Blue would be typed in
Orange, Pink in Black, etc.
Example:
Blue Purple Red Green Purple Green
Subjects
were then instructed to say the name of the ink color and ignore the text. It
took 110 seconds to complete a list of this type compared to 63 seconds to name
the colors when presented in the form of solid squares. The naming time nearly
doubled in the presence of conflicting color words, an effect known as the
Stroop Effect.
1950-1974
In the
1950s, research psychologists renewed their interest in attention when the
dominant epistemology shifted from positivism (i.e., behaviorism) to realism
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.
Broadbent's
Filter Model of Attention states that information is held in a pre-attentive
temporary store, and only sensory events that have some physical feature in
common are selected to pass into the limited capacity processing system. This
implies that the meaning of unattended messages is not identified. Also, a
significant amount of time is required to shift the filter from one channel to
another. 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), attention shuts down (in
Broadbent's model) or attenuates (in Triesman's refinement) 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.
In the
1960s, Robert Wurtz at the National Institutes of Health began recording
electrical signals from the brains of macaques 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
mid-1970s, multiple resource models were put forth. These studies showed that it
is easier to perform two tasks together when the tasks use different stimulus or
response modalities than when they use the same modalities. Michael Posner did
research on space-based versus object-based approaches to attention in the
1980s. For space-based attention, attention is likened to that of a spotlight.
Attention is directed to everything in the spotlight's
field.
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
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.[citation needed]
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
Selective
attention
The spotlight model of attention.
Visual attention
In cognitive
psychology 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 inspired by the work of William James who described attention as
having a focus, a margin, and a fringe.[16] 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 that 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.
Auditory
Attention
Selective
Auditory Attention
Divided
attention
Divided
attention is the task of actively paying attention to more than one task at a
time, and it is both important and common in every day life. It is rare for
someone to be engaged in just one task.
Divided
attention can be improved with practice. Spelke, Hirst, and Niesser (1976)
studied accuracy and response time of performance by participants reading short
stories and writing down dictated words. The participants’ initial performance
was very poor when both tasks were performed simultaneously, but after
participants practiced the tasks 5 days a week for 85 sessions, their
performance improved for both tasks (Sternberg & Sternberg, 2012). Spelke
and others have proposed that it is possible that controlled tasks can be
automatized, thus using fewer attentional resources. In addition, how well
people divide their attention has to do with that person's intelligence (Hunt
& Lansman, 1982, as cited in Sternberg & Sternberg, 2012). According to
researchers, more intelligent people can timeshare between two tasks and
effectively perform two tasks better.
There have
been multiple theories regarding divided attention. One, conceived by Kahneman
in 1973, explains that there is a single pool of attentional resources that can
be freely divided among multiple tasks. This model seems to be too
oversimplified, however, due to the different modalities (e.g., visual,
auditory, verbal) that we perceive (Sternberg & Sternberg, 2012). When the
two tasks are from the same modality, such as listening to a radio station and
writing a paper, it is much more difficult to concentrate on both because the
tasks are likely to interfere with each other. The specific modality model was
theorized by Navon and Gopher in 1979. Although this model is more adequate at
explaining divided attention among simple tasks, resource theory is another,
more accurate metaphor for explaining divided attention on complex tasks.
Resource theory demonstrates that as we automatize each complex task, performing
that task requires less of our limited-capacity attentional resources (Sternberg
& Sternberg, 2012).
Other
variables play a part in our ability to pay attention to and concentrate on many
tasks at once. These include, but are not limited to, anxiety, arousal, task
difficulty, and skills (Sternberg & Sternberg, 2012). Attention is a very
multi-faceted process and it is better understood now due to cognitive research
and the study of the brain.
Bottom-Up vs
Top-Down
Researchers
have described two different aspects of how our minds come to attend to items
present in the environment.
The first
aspect is called bottom-up processing, also known as stimulus-driven attention
or exogenous attention. These describe attentional processing which is driven by
the properties of the objects themselves. Some processes, such as motion or a
sudden loud noise, can attract our attention in a pre-conscious, or
non-volitional way. We attend to them whether we want to or not. These aspects
of attention are thought to involve parietal and temporal cortices, as well as
the brainstem.
The second
aspect is called top-down processing, also known as goal-driven, endogenous
attention, attentional control or executive attention. This aspect of our
attentional orienting is under the control of the person who is attending. It is
mediated primarily by the frontal cortex and basal ganglia as one of the
executive functions. Research has shown that it is related to other aspects of
the executive functions, such as working memory and conflict resolution and
inhibition.
Overt and
covert attention
Attention
may be differentiated according to its status as "overt" versus "covert". Overt
attention is the act of directing sense 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 a 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.
Influence of
processing load
One theory
regarding selective attention is the cognitive 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.
Clinical
model of attention
Attention is
best described as the sustained focus of cognitive resources on information
while filtering or ignoring extraneous information. Attention is a very basic
function that often is a precursor to all other neurological/cognitive
functions. As is frequently the case, clinical models of attention differ from
investigation models. One of the most used models for the evaluation of
attention in patients with very different neurologic pathologies is the model of
Sohlberg and Mateer. This hierarchic model is based in the recovering of
attention processes of brain damage patients after coma. Five different kinds of
activities of growing difficulty are described in the model; connecting with the
activities those patients could do as their recovering process
advanced.
Focused attention: The ability to respond discretely to specific
visual, auditory or tactile stimuli.
Sustained attention (vigilance): The
ability to maintain a consistent behavioral response during continuous and
repetitive activity.
Selective attention: The ability to maintain a
behavioral or cognitive set in the face of distracting or competing stimuli.
Therefore it incorporates the notion of "freedom from
distractibility."
Alternating attention: The ability of mental flexibility
that allows individuals to shift their focus of attention and move between tasks
having different cognitive requirements.
Divided attention: This is the
highest level of attention and it refers to the ability to respond
simultaneously to multiple tasks or multiple task
demands.
This model
has been shown to be very useful in evaluating attention in very different
pathologies, correlates strongly with daily difficulties and is especially
helpful in designing stimulation programs such as attention process training, a
rehabilitation program for neurologic patients of the same
authors.
Neural
correlates of attention
Most
experiments show that one neural correlate 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:
Working
memory 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).
Neutrally,
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 fields (FEF) on the dorsolateral frontal
cortex contain a retinocentric spatial map. Microstimulation in the FEF induces
monkeys to make a saccade 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. Many animals, including humans,
produce gamma waves (40–60 Hz) when focusing attention on a particular object or
activity.
Another
commonly used model for the attention system has been put forth by researchers
such as Michael Posner divides attention into three functional components:
alerting, orienting, and executive attention.
Alerting is the process
involved in becoming and staying attentive toward the surroundings. It appears
to exist in the frontal and parietal lobes of the right hemisphere, and is
modulated by norepinephrine.
Orienting is the directing of attention to a
specific stimulus.
Executive attention is used when there is a conflict
between multiple attention cues. It is essentially the same as the central
executive in Baddeley's model of working memory. The Eriksen flanker task has
shown that the executive control of attention may take place in the anterior
cingulate cortex
Cultural
variation
Children
appear to develop patterns of attention related to the cultural practices of
their families, communities, and the institutions in which they
participate.
In 1955
Henry suggested that there are societal differences in sensitivity to signals
from many ongoing sources that call for the awareness of several levels of
attention simultaneously. He tied his speculation to ethnographic observations
of communities in which children are involved in a complex social community with
multiple relationships.
Attention
can be focused in skilled ways on more than one activity at a time, which can be
seen in different communities and cultures such as the Mayans of San Pedro. One
example is simultaneous attention which involves uninterrupted attention to
several activities occurring at the same time. Another cultural practice that
may relate to simultaneous attention strategies is coordination within a group.
San Pedro toddlers and caregivers frequently coordinated their activities with
other members of a group in multiway engagements rather than in a dyadic
fashion.
Attention
modelling
In the
domain of computer vision, efforts have been made in modelling the mechanism of
human attention, especially the bottom-up attentional
mechanism.
Generally
speaking, there are two kinds of models to mimic the bottom-up saliency
mechanism. One way is based on the spatial contrast analysis. For example, in a
center-surround mechanism is used to define saliency across scales, which is
inspired by the putative neural mechanism. It has also been hypothesized that
some visual inputs are intrinsically salient in certain background contexts and
that these are actually task-independent. This model has established itself as
the exemplar for saliency detection and consistently used for comparison in the
literature.; the other way is based on the frequency domain analysis. This
method was first proposed by Hou et al., this method was called SR, and then
PQFT method was also introduced. Both SR and PQFT only use the phase
information. In 2012, the HFT method was introduced, and both the amplitude and
the phase information are made use
of.