p.631 Issues of attention bear on every area of cognitive science. In addition to the questions that arise within individual cognitive domains, students of attention find themselves confronted, inevitably, by the problems of integration and coordination among different cognitive domains in the overall control of behavior. The latter constitute traditionally the central problems for theories of attention and must be counted surely among the most complex and difficult problems in cognitive science.

p.631 What would a computational theory that was adequate to the functions of attention be like? What is the overall purpose (or what are the overall purposes) of attention, and what are the determining and enabling constraints on attentional processes?

p.632 I have tried to set out a conceptual framework for the functions of visual attention that offers an alternative to the traditional preoccupation with issues of limited capacity and selectivity of "processing."

p.632 To keep things within manageable bounds, the discussion is confined to certain functions of visual attention, in the context of immediate perceptual-motor activities.

p.632-633 The fundamental constraint that underlies all the operations of attention, imposing their essentially selective character, is the limited information-processing capacity of the brain... Hence... the basic function or purpose of attentional mechanisms is to protect the brain's limited capacity system (or systems) from informational overload

p.647 I have noted also evidence for a significant interdependence between the orienting of spatial attention and the preparation for action.

p.648 Many authors have suggested that the selectivity of attention is in some way related to or dependent on the need for coherent control of action

p.649 The necessary control of action of course includes decisions not to perform a given action... Selection among competing sources of control parameters in the sensory input is equally essential for the coherence of action preparation, or action planning... The attentional selectivity with which we are concerned is therefore selection for potential control of action.

p.649 When the conditions for two or more intended actions conflict, then one or both must be modified sufficiently to enable their continued execution. Failing that, one activity must be given priority while the other is postponed or abandoned.

p.650 (possibly very complex) processes of perceptual grouping and segmentation may have logically to precede the effective focusing of visual selection-for-action.

p.651-652 First, we are concerned with systems that have to operate in an environment that is, at best, only partly or incompletely predictable. Furthermore it is an environment that can change at any moment extremely rapidly, in ways that may be of critical importance for the organism... Second, we are concerned with systems with a very wide range of potential goals of action. Priority... must be continuously adjusted.... Third, we are concerned with multi-functional organisms... organisms (or robots) whose subcomponents... are not in general uniquely dedicated to particular goals or to particular categories of action... The primary purpose of an attentional system must be to ensure the coherence of behavior under these often conflicting constraints. Coherent, goal-directed behavior requires processes of selective priority assignment and coordination at many different levels (motivational, cognitive, motor, sensory). Together this set of selective and coordinative processes can be said to make up the effective attentional engagement (or attentional set) of an organism at any moment.

p.652 Processes responsible for establishing and maintaining coherent, attentional engagement must involve a number of... separable elements... :

• selective priority assignment among competing...goals... for control of immediate action;
• the engagement... of specific cognitive subsystems...
• selective recruitment... of appropriate effectors;
• selective priority assignment among competing available information sources... for control of specific parameters of action (selection-for-action);

p.652-653 The critical problem for any attentional system (in multifunctional organisms) is therefore how to satisfy two conflicting requirements: the need for continuity of attentional engagement, against the need for its interruptibility. Failure to shift attentional engagement when faced by environmental threats (or opportunities) can of course be fatal to an organism's survival or physical integrity. At the other extreme constant shifting or fragmentation of attentional engagement, triggered by every sensory event of environmental affordance, would make sustained, purposeful activity impossible and result only in behavioral chaos. Between these two equally disastrous extremes lies a range of more or less viable solutions. All of them depend on some means of evaluating, or at least estimating, the relative motivational importance and temporal urgency of the potential threats and affordances outside the current attentional engagement, relative to the estimated importance and urgency of the current activity or activities. (Both variables - urgency and long-term importance - are needed and should presumably be able to trade off against one another.)

p.653 Humans (and other species) appear to have adopted a combination of several different partial solutions to this problem... (1) internally generated, predictive control of attention shifting... (2) externally elicited shifts of attentional engagement, cued by the detection of more or less complex triggering conditions; and (3) active combinations of (1) and (2), as, for example, in many forms of exploration and search. I should therefore add, as a further indispensable attentional function, continuous (parallel) monitoring of the environment... for changes relevant to current and long-term goals.

p.653 Environmental monitoring may be expected to operate at many different levels. These should include fast, relatively crude or approximate systems, operating on rule-of-thumb (that is, associative) criteria, both learned and unlearned, as well as possibly slower... systems, supported also by processes of (discontinuous) predictive search under goal-directed control. Detection of a critical external or internal event... must be capable of triggering attentional orienting. Equally important, sensory-motor orienting must be capable of being inhibited by the competing, higher priority of the current attentional engagement.

Computation of this critical balance of priorities appears to be one of the central problems for any system of intelligent attentional control.

p.654 the processes of visual-spatial selection-for-action are instrumental to a number of different, and... competing, attentional functions or purposes: (1) to implement (and to protect the coherence of) the current attentional engagement; (2) to enable endogenously controlled [JLJ - from within] shifts of perceptual-motor engagement... and (3) to enable exogenously elicited [JLJ - from outside], visual-spatial orienting, in particular orienting cued by... visual events.

p.654 executive control is exercised only indirectly, typically through a mechanism of competitive priority assignments.

p.655 I have contrasted two different conceptions of attention and attentional selectivity. The first of these depends on the idea of limited capacity, in various forms, as the causal origin of attentional phenomena. The second, contrasting set of assumptions focuses on the necessity of attentional engagement - in particular, in many perceptual-motor activities, the need for what I have called selection-for-action - as a condition of behavioral coherence in multifunctional organisms.

p.657 In studies of selective response and selective monitoring tasks, certain stimuli (or stimulus attributes) in a visual array are designated by the experimenter as relevant to control a speeded response (targets) and others as irrelevant and to-be-ignored (distractors). In these paradigms there is extensive evidence that many other dimensions of relevance to the subject's current goals and interests... in addition to the experimenter's instructions, affect the efficiency of selection-for-action.

p.657 Johnston and Dark (1986) summarized a range of such results in two empirical generalizations: (1) "All levels of stimulus analysis can be primed for particular stimuli," and (2) "Stimuli conforming to active schemata are easy to attend to, but difficult to ignore." (Or more generally, "Selective attention can be guided by active schemata.")

p.661 The experimental paradigms discussed here are relevant to issues of attentional selectivity in the visual control of immediate action or immediate response.

p.662 according to many theorists... attention has been conceptualized as some unspecified but essentially limited mental energy or resource or capacity. What this resource supposedly enables is processing. Or rather, it enables certain sorts of processing ("further processing"). Other sorts of processing do not need attention.

p.662 How else could attention be conceptualized? [JLJ - Define attention without using the concept of attention. Hmm. Given that an organism must do something, attention represents a behavior that, if done, has good payback potential - now or later - for survival, finance, social interaction or general well-being. For example, for a scholar, attending in class has the potential payback of good grades and a good job. For an intern or apprentice, watching experienced workers do their job and asking questions has the potential payback of learning enough to do that job and earn a living. etc. Attention is a strategic tuning and retuning of cognitive resources to the situation-relevant information flows, so that whatever is sensed/retained (perhaps initially combined with a lesson or pointers from a teacher, even if later self-taught, or instinctive) has potential use later in plausible action, contest or crisis. We wisely attend to those things that our future self would have wished us to have attended to, if surprised by a plausible situation such as an unexpected audit or challenge, and we were not ready. We did not study in college, got C's, and was not able to land a good job. Guess I should have studied and paid more attention in class. We attend to our speedometer so that we will not be surprised by getting a speeding ticket. We attend in general because the invested effort spent in the act of attending has a payback later - results - that are deemed worth the effort spent. Certain things attended, such as watching television, do not have good payback later, while other things attended, such as teachers or reading books for class, do have good payback. We attend as part of a well-intentioned strategy scheme, so that the future, when it arrives, is somehow measurably better for us [and no worse] than if we did not attend.]

p.662-663 Within the domain of perceptual-motor performance... it may be a more fruitful heuristic to focus research on a different set of questions regarding the functions of visual attention. These questions are... about the mechanisms of attentional control: questions about the... computational mechanisms by which attentional engagement is established, coordinated, maintained, interrupted, and redirected, both in spatial and nonspatial terms, in the preparation and control of action.