Covert orienting is the act to mentally shifting one's focus without moving one's eyes. Covert orienting has the potential to affect the output of perceptual processes by governing attention to particular items or locations for example, the activity of a V4 neuron whose receptive field lies on an attended stimuli will be enhanced by covert attention  but does not influence the information that is processed by the senses.
Researchers often use "filtering" tasks to study the role of covert attention of selecting information. These tasks often require participants to observe a number of stimuli, but attend to only one. 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.
There are studies that suggest the mechanisms of overt and covert orienting may not be controlled separately and independently as previously believed. Central mechanisms that may control covert orienting, such as the parietal lobe, also receive input from subcortical centres involved in overt orienting. Orienting attention is vital and can be controlled through external exogenous or internal endogenous processes.
However, comparing these two processes is challenging because external signals do not operate completely exogenously, but will only summon attention and eye movements if they are important to the subject. Exogenous from Greek exo , meaning "outside", and genein , meaning "to produce" orienting is frequently described as being under control of a stimulus. This often results in a reflexive saccade. Since exogenous cues are typically presented in the periphery, they are referred to as peripheral cues.
Exogenous orienting can even be observed when individuals are aware that the cue will not relay reliable, accurate information about where a target is going to occur. This means that the mere presence of an exogenous cue will affect the response to other stimuli that are subsequently presented in the cue's previous location. Several studies have investigated the influence of valid and invalid cues. Posner and Cohen noted a reversal of this benefit takes place when the interval between the onset of the cue and the onset of the target is longer than about ms.
Endogenous from Greek endo , meaning "within" or "internally" orienting is the intentional allocation of attentional resources to a predetermined location or space. Simply stated, endogenous orienting occurs when attention is oriented according to an observer's goals or desires, allowing the focus of attention to be manipulated by the demands of a task. In order to have an effect, endogenous cues must be processed by the observer and acted upon purposefully.
These cues are frequently referred to as central cues. This is because they are typically presented at the center of a display, where an observer's eyes are likely to be fixated. Central cues, such as an arrow or digit presented at fixation, tell observers to attend to a specific location. When examining differences between exogenous and endogenous orienting, some researchers suggest that there are four differences between the two kinds of cues:. There exist both overlaps and differences in the areas of the brain that are responsible for endogenous and exogenous orientating. Researchers of this school have described two different aspects of how the mind focuses attention 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. 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. 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.
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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. Attention is best described as the sustained focus of cognitive resources on information while filtering or ignoring extraneous information.
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. 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.
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 neurological patients of the same authors.
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 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. Another commonly used model for the attention system has been put forth by researchers such as Michael Posner.
He divides attention into three functional components: Children appear to develop patterns of attention related to the cultural practices of their families, communities, and the institutions in which they participate. In , Jules 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. Many Indigenous children in the Americas predominantly learn by observing and pitching in.
There are several studies to support that the use of keen attention towards learning is much more common in Indigenous Communities of North and Central America than in a middle-class European-American setting. Keen attention is both a requirement and result of learning by observing and pitching-in. Incorporating the children in the community gives them the opportunity to keenly observe and contribute to activities that were not directed towards them.
It can be seen from different Indigenous communities and cultures, such as the Mayans of San Pedro , that children can simultaneously attend to multiple events. One example is simultaneous attention which involves uninterrupted attention to several activities occurring at the same time. San Pedro toddlers and caregivers frequently coordinated their activities with other members of a group in multiway engagements rather than in a dyadic fashion.
This learning by observing and pitching-in model requires active levels of attention management. The child is present while caretakers engage in daily activities and responsibilities such as: Eventually the child is expected to be able to perform these skills themselves. In the domain of computer vision , efforts have been made to model the mechanism of human attention, especially the bottom-up intentional mechanism  and its semantic significance in classification of video contents  .
Both spatial attention and temporal attention have been incorporated in such classification efforts. Generally speaking, there are two kinds of models to mimic the bottom-up salience mechanism in static images. One way is based on the spatial contrast analysis. For example, a center—surround mechanism has been used to define salience across scales, inspired by the putative neural mechanism. This model has established itself as the exemplar for salience 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. Hemispatial neglect, also called unilateral neglect , often occurs when people have damage to their right hemisphere. Damage to the left side of the brain the left hemisphere rarely yields significant neglect of the right side of the body or object in the person's local environments. The effects of spatial neglect, however, may vary and differ depending on what area of the brain was damaged. Damage to different neural substrates can result in different types of neglect.
Attention disorders lateralized and nonlaterized may also contribute to the symptoms and effects. New technology has yielded more information, such that there is a large, distributed network of frontal, parietal, temporal, and subcortical brain areas that have been tied to neglect. Social attention is one special form of attention that involves the allocation of limited processing resources in a social context. Previous studies on social attention often regard how attention is directed toward socially relevant stimuli such as faces and gaze directions of other individuals.
In one extreme, individual tends to attend to the self and prioritize self-related information over others', and, in the other extreme, attention is allocated to other individuals to infer their intentions and desires. Attending-to-self and attending-to-others mark the two ends of an otherwise continuum spectrum of social attention. For a given behavioral context, the mechanisms underlying these two polarities might interact and compete with each other in order to determine a saliency map of social attention that guides our behaviors.
Berlyne credits the first extended treatment of attention to philosopher Nicolas Malebranche in his work "The Search After Truth". 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". 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.
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. In the beginning of the 19th century, it was thought 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. 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 Wilhelm Wundt introduced the study of attention to the field of psychology.
The Problem of the Locus of Selection
Wundt measured mental processing speed by likening it to differences in stargazing measurements. Astronomers 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.
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He also differentiated between three types of reactions: 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. James differentiated between censorial attention and intellectual attention. Censorial 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: According to James, attention has five major effects.
Attention works to make us perceive, conceive, distinguish, remember, and shorten reactions time. During this period, research in attention waned and interest in behaviorism flourished, leading some to believe, like Ulric Neisser , that in this period, "There was no research on attention". However, Jersild published very important work on "Mental Set and Shift" in He stated, "The fact of mental set is primary in all conscious activity.
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The same stimulus may evoke any one of a large number of responses depending upon the contextual setting in which it is placed". 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 , Telford discovered the psychological refractory period. The stimulation of neurons is followed by a refractory phase during which neurons are less sensitive to stimulation.
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, and so on.
Subjects were then instructed to say the name of the ink color and ignore the text. It took seconds to complete a list of this type compared to 63 seconds to name the colors when presented in the form of solid squares. In the s, research psychologists renewed their interest in attention when the dominant epistemology shifted from positivism i.
Modern research on attention began with the analysis of the " cocktail party problem " by Colin Cherry in 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.
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.
In the light of the large number of functional domains and the enormous amount of knowledge on selection, competition, selectivity and priority control in each of these individual domains, this Theme Issue deliberately restricts itself by imposing additional constraints beyond the fundamental notion of attentional across-domain integration by biased competition. We therefore focus on vision integration of biased competition in visual perception, visual memory and visual action , on task-driven control of attentional integration and on real-world stimuli, scenes and behaviour as a paradigmatic case, in which attentional integration is evidently required.
Our focus of visual perception, memory and action had several reasons. First, during the past decades, our knowledge about visual information processing has grown tremendously [ 31 , 32 ]. This enormous progress has been based on experimental paradigms for studying specific functional domains such as visual attention [ 33 ], object recognition [ 34 ], visual short-term memory [ 35 ] or visual-based sensorimotor control [ 24 , 36 ]. The wealth of research paradigms and empirical data make research within the visual modality an optimal vantage point for further analysis. Second, we choose vision as a model system in that such a research focus allows the tackling of one of the greatest challenges of interdisciplinary research, namely variability in terms of methods, spatial and temporal scales, and theoretical languages.
The complete aforementioned toolkit of research methods—electrophysiology, functional imaging, lesion studies and advanced behavioural methods—is accepted and used in all domains of vision research. Moreover, shared theoretical tools such as mathematical and computational modelling e.
To conclude, vision provides the tools and terminology an integrated view will be built upon, and in turn, vision serves as prime test bed for experimental validation. Third, a substantial and increasing body of experimental work exists already that investigates how attentional processes might link visual perception, memory and action. These studies have focused, for instance, on how attention and working memory processes could interact [ 30 , 37 , 38 ], on how covert visual attention in perception and motor action selection may be coupled [ 39 — 41 ] or on how retrieval from long-term memory and action selection might be linked [ 42 ].
Biased competition in functional domains has to be integrated in order to achieve coherency in goal-directed behaviour and cognition. We suggest that common priority signals from the current task play a key role in this integration. At any given point in time, there should always be one unique task or intention, action plan at the highest level of control in mind and brain, and thus in control of attention [ 11 , 43 — 45 ].
Attentional selection in visual perception, memory and action: a quest for cross-domain integration
Even when several tasks are seemingly being carried out in parallel, a common action plan i. What is a task? We are committed to a relative broad working definition. Goal states—sometimes also called intentions—define a reference value or set point. To reach the reference value, task-specific information for priority control and biasing of competition is required, namely a description of relevant objects, events and actions [ 10 , 43 , 44 ]. References to stimuli and actions, as well as regularities connecting them, are also important ingredients to tasks [ 50 ].
Experimental evidence points to a central role of the prefrontal cortex PFC [ 45 , 50 — 52 ]. For instance, if you are reading a book in your room and you smell a fire, then it is highly probable that the current task of reading will be immediately replaced by the new task of locating the fire and escaping from it. Again, the PFC is critical for this function [ 23 ]. The need for integration across functional domains becomes most evident when dealing with natural settings and real-world tasks.
Traditional psychophysics has, by contrast, emphasized well-controlled i. Frequently, such research implicitly or explicitly assumes that complex processing will then be eventually understood by combining results from simple stimuli [ 54 ]; this implies, however, linear processes that seem in sharp contrast to the highly nonlinear nature of perceptual and cognitive processing.
Provided the tight link between gaze and covert attention [ 10 , 20 ], tracking eye movements and measuring gaze allocation present one of the most promising paradigms for studying attentional processes in real-world vision. For a long time, experiments in this area were restricted to constrained laboratory settings, introducing biases [ 55 ], often neglecting head and body movements, and providing limited information for real-world situations [ 56 ]. Only recently, with the advent of powerful wearable eye trackers and virtual reality technology, real-world tasks and stimuli could be combined with less and less constrained settings.
The key challenge for such endeavours is to allow the experimenter sufficient control over the experimental setting, without compromising the realism of the task and task set. Only when understanding—as proposed throughout this Theme Issue—attention as a combination of priority control and competition within and across domains as well as based on a solid theoretical and modelling framework [ 45 , 62 — 67 ], quantitative hypotheses can be formulated that eventually allow both—a fully realistic scenario task and environment and sufficient experimental control.
In this Theme Issue, we therefore use real-world tasks and natural stimuli as paradigmatic cases for integration of attentional selection across domains [ 22 , 26 , 28 ]. In this Theme Issue, we bring together data and models based from a large variety of fields, including theoretical modelling, classical psychophysical experiments across the domains of perception, memory and action, real-world perception and action, as well as monkey electrophysiology.
The Theme Issue opens with a review by Humphreys et al. This provides an important constraint on formal theories of attention, namely the requirement to include affordances, even if seemingly perceptually complex, in the guidance of attention. In this spirit of action-related attention, Flanagan et al. They find that proactive gaze behaviour, similar to the one preparing one's own actions, is elicited if and only if the evaluation of a mechanical event—judging the weight of an object lifted by someone else—is required, when compared with observing the visually identical situation with the task of predicting the choice of an item.
Indeed, they find that orientation-discrimination performance is better and apparent contrast higher at the reach target. However, unlike for eye movements, these effects show a distinct temporal evolution, suggesting two distinct mechanisms for performance benefits, which are in this view linked to movement preparation, and visual appearance, which is linked to priority. Theeuwes [ 70 ] provides a detailed review on the literature on feature-based attention and argues that there is little evidence for endogenous, top-down control in feature-based attention and thus advocates a view that all feature-based attention could be explained fully by bottom-up priming, in contrast to the predominate role of top-down control in spatial attention, which is at the focus of many other studies in this Theme Issue.
Because parameters related to temporal expectancy turn out to be simple linear functions of the model's internal parameters, the article naturally extends the scope of TVA to relevant experimental parameters in the temporal domain. Models of attention such as TVA typically focus on attention deployment within a single fixation, whereas there is little theoretical work on the relation between memory and attention across an eye movement.
Rooted in TVA, Schneider [ 30 ] proposes a complementary approach to model effects of attention and working memory across competition episodes. The novel model task-driven visual attention and working memory; TRAM unifies a series of experiments in attention and memory, in particular in the context of the attentional blink, which so far have modelled largely in isolation, in a single theory. Together, these papers exemplify the potential of formal theories of attention, in particular TVA and its descendants, for explaining a large variety of phenomena across domains.
Only items that are immediately relevant for a task are retained in an active memory state, whereas non-immediately relevant items are stored in a more passive form of representation. Only the active representation influences visual selection and search, even if retrieval performance for actively and passively stored memories is similar. A series of articles in this Theme Issue address whether and how results and models from the laboratory transfer to more realistic scenarios and tasks.
They find that the fixation probability on an object during prolonged viewing correlates with its probability to be detected in a rapid-serial-visual presentation sequence, thereby relating overt attention in space to covert attention in time. Thereby, the model extends models of template search to the more naturalistic search mode, when no exact template, but only the category of the natural target object is given.
They show that the priority given to natural objects in a real-world task tea-making for both for gaze allocation and memorization is modulated by whether an observer is actually performing the task or merely watching it. Specifically, task-relevant items are fixated longer and their position is remembered better, if and only if the observer is actively engaged in the task. The benefit for position memory still holds if the observer is moving through the real-world setting without manipulating the objects when compared with watching head-centred recordings , whereas the gaze preference requires active object manipulation.
They show that the lightness perception of two physically identical stimuli influences sampling by eye movements, and in turn, this sampling strategy modulates lightness perception. Following segmentation of a stimulus into target and occluder, fixations preferentially land on the target and thereby modulate lightness perception, and both fixations and perception are similarly affected if segmentation is no longer possible.
In summary, these papers exemplify the integration of selection across domains for naturalistic situations: The Theme Issue concludes by three electrophysiological studies that provide some of the neural basis for the theories, concepts and behavioural data discussed above. They find that a potential target that has previously been fixated i. As such, the paper provides a substrate for involvement of memory in modulating current perceptual and attentional processing. Contrary to the standard view, which presumes a role of PFC in suppressing unwanted behaviour, they review recent evidence in favour of PFC's role as facilitator of goal-directed saccades.
This evidence, in particular, draws on primarily excitatory connection of the PFC to the superior colliculus in the macaque. In this view, PFC facilitates goal-directed behaviour and plays a decisive role in implementing and maintaining the task set. While they confirm that stochastic accumulator models provide a quantification of behaviour at large in the non-human primate, they provide compelling evidence that a one-to-one mapping of the model to neural activity falls short.
Instead, they propose a multi-stage accumulator model that is consistent with both the behavioural and the currently available neuronal data. Together, the three electrophysiological papers mirror the themes of the whole issue, cross-domain integration and task as control factor: Working with this ZiF research group was scientifically and personally in many respects rewarding—we are very grateful to all members of the ZIF groups and the numerous other researchers that came to the ZiF and contributed to this great research year — see http: We are very grateful to Britta Padberg and her team for the splendid hospitality during this year.
The papers of this Theme Issue are based on invited contributions of the opening conference of the ZiF research group in October National Center for Biotechnology Information , U. This article has been cited by other articles in PMC. Abstract For decades, the cognitive and neural sciences have benefitted greatly from a separation of mind and brain into distinct functional domains. Functional domains of mind and brain: Attention as biased competition: This Theme Issue at a glance In this Theme Issue, we bring together data and models based from a large variety of fields, including theoretical modelling, classical psychophysical experiments across the domains of perception, memory and action, real-world perception and action, as well as monkey electrophysiology.
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Deco G, Rolls ET. Attention, short-term memory, and action selection: The temporal flexibility of attentional selection in the visual cortex. A neural theory of visual attention and short-term memory NTVA. Neuropsychologia 49 , — doi: Fecteau J, Munoz D. Salience, relevance, and firing: Attention, intention, and priority in the parietal lobe. Habekost T, Starrfelt R. Deubel H, Schneider WX. Saccade target selection and object recognition: Memory and prediction in natural gaze control.
B , doi: Everling S, Johnston K. Control of the superior colliculus by the lateral prefrontal cortex. Mirpour K, Bisley JW. Evidence for differential top-down and bottom-up suppression in posterior parietal cortex. Priorities for selection and representation in natural tasks.