The theoretical framework presented in this article explains expert performance as the end result of individuals ' prolonged efforts to improve performance while negotiating motivational and external constraints. In most domains of expertise, individuals begin in their childhood a regimen of effortful activities (deliberate practice) designed to optimize improvement. Individual differences, even among elite performers, are closely related to assessed amounts of deliberate practice. Many characteristics once believed to reflect innate talent are actually the result of intense practice extended for a minimum of 10 years. Analysis of expert performance provides unique evidence on the potential and limits of extreme environmental adaptation and learning. Our civilization has always recognized exceptional individuals, whose performance in sports, the arts, and science is vastly superior to that of the rest of the population. Speculations on the causes of these individuals ' extraordinary abilities and performance are as old as the first records of their achievements. Early accounts commonly attribute these individuals' outstanding performance to divine intervention, such as the

Number sense " is a short-hand for our ability to quickly understand, approximate, and manipulate numerical quantities. My hypothesis is that number sense rests on cerebral circuits that have evolved specifically for the purpose of representing basic arithmetic knowledge. Four lines of evidence suggesting that number sense constitutes a domain-specific, biologically-determined ability are reviewed: the presence of evolutionary precursors of arithmetic in animals; the early emergence of arithmetic competence in infants independently of other abilities, including language; the existence of a homology between the animal, infant, and human adult abilities for number processing ; and the existence of a dedicated cerebral substrate. In adults of all cultures, lesions to the inferior parietal region can specifically impair number sense while leaving the knowledge of other cognitive domains intact. Furthermore, this region is demonstrably activated during number processing. I postulate that higher-level cultural developments in arithmetic emerge through the establishment of linkages between this core analogical representation (the " number line ") and other verbal and visual representations of number notations. The neural and cognitive organization of those representations can explain why some mathematical concepts are intuitive, while others are so difficult to grasp. Thus, the ultimate foundations of mathematics rests on core representations that have been internalized in our brains through evolution.

When exposed to a regular stimulus field, for instance, that generated by an artificial grammar, subjects unintentionally learn to respond efficiently to the underlying structure (Miller, 1958; Reber 1967). We explored the hypothesis that the learning process is chunking and that grammatical knowledge is implicitly encoded in a hierarchical network of chunks. We trained subjects on exemplar sentences while inducing them to form specific chunks. Their knowledge was then assessed through judgments ofgrammaticality. We found that subjects were less sensitive to violations that preserved their chunks than to violations that did not. We derived the theory of competitive chunking (CC) and found that it successfully reproduces, via computer simula-tions, both Miller's experimental results and our own. In CC, chunks are hierarchical structures strengthened with use by a bottom-up perception process. Strength-mediated competitions determine which chunks are created and which are used by the perception process. The world is regular, and people are efficient regularity detectors. Sometimes people are intentionally looking for structural regularities. Other times, however, people learn to respond to structured stimuli even though they do not suspect

Abstract—An approach is explicitly formulated to blend a local with a global theory to investigate oscillatory neocortical firings, to determine the source and the information-processing nature of the alpha rhythm. The basis of this optimism is founded on a statistical mechanical theory of neocortical interactions which has had success in numerically detailing properties of short-term-memory (STM) capacity at the mesoscopic scales of columnar interactions, and which is consistent with other theory deriving similar dispersion relations at the macroscopic scales of electroencephalographic (EEG) and magnetoencephalographic (MEG) activity.

A fundamental aspect of multiple task management is attending to new stimuli and integrating associated task requirements into an ongoing task set- this is ``interruption management'' (IM). Anecdotal evidence and field studies indicate the frequency and consequences of interruptions, however experimental investigations of mechanisms influencing IM are scarce. Interruptions on commercial flightdecks are numerous, of various forms, and have been cited as contributing factors in many aviation incident and accident reports. This research grounds an experimental investigation of flightdeck interruptions in a proposed IM stage model. This model organizes basic research, identifies influencing mechanisms, and suggests appropriate dependent measures for IM. Fourteen airline pilots participated in a flightdeck simulation experiment to investigate the general effects of performing an interrupting task and interrupted procedure, and the effects of specific task factors: (1) modality; (2) embeddedness, or goal­level, of an interruption; (3) strength of association, or coupling­strength, between interrupted tasks; (4) semantic similarity; and (5) environmental stress. General effects of interruptions were extremely robust. All individual task factors significantly affected interruption management, except ``similarity.'' Results extend the Interruption Management model, and are interpreted for their implications for interrupted flightdeck performance and intervention strategies for mitigating their effects on the flightdeck.

Abstract. VR offers the potential to develop human testing and training environments that allow for the precise control of complex stimulus presentations in which human cognitive and functional performance can be accurately assessed and rehabilitated. However, basic feasibility issues need to be addressed in order for this technology to be reasonably and efficiently applied to the neuropsychological assessment (NA) and cognitive rehabilitation (CR) of persons with acquired brain injury and neurological disorders. This chapter will provide an introduction to the basic concepts of neuropsychological assessment and cognitive rehabilitation along with rationales for virtual realityÕs applicability in these complimentary fields. We review the relevant literature regarding theoretical and pragmatic issues for these applications, and provide a description of our ongoing work developing a mental rotation/spatial skills cognitive assessment and training system. References are provided in each section for further reading in each area reviewed. 1.

The extent to which memory for information content is reliable, trustworthy, and accurate is crucial in the information age. Being forced to divert attention to interrupting messages is common, however, and can cause memory loss. The memory e#ects of interrupting messages were investigated in three experiments. In Experiment 1, attending to an interrupting message decreased memory accuracy. Experiment 2, where four interrupting messages were used, replicated this result. In Experiment 3, an interrupting message was shown to be most disturbing when it was semantically very close to the main message. Drawing from a theory of long-term working memory it is argued that interrupting messages can both disrupt the active semantic elaboration of content during encoding and cause semantic interference upon retrieval. Properties of the interrupting message a#ect the extent and type of errors in remembering. Design implications are discussed.

This article investigates how and why people remember the existence of hidden information. To obtain data on this kind of memory phenomenon, we observed an experienced programmer doing her own work at her own computer. The programmer's interaction with the computer generates much more information than fits on the screen at once. Most of this information is hidden, scrolled out of the way by the programming environment to make Direct all correspondence to: Erik M. Altmann, George Mason University, Human Factors & Applied Cognition, Mailstop 2E5, Fairfax, VA 22030 USA; E-Mail: altmann@gmu.edu

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We examine the effect of environmental cues on being interrupted while performing a task. We conducted an experiment in which participants, after an interruption, received either a blatant environmental cue of their previous action (a red arrow), a subtle environmental cue of their previous action (a cursor that was placed in the same location as their previous action), or no environmental cue at all. We found that participants in the blatant condition resumed their task faster than participants in the other two conditions. Furthermore, a subtle environmental cue was no better than no cue at all. The results support our model of memory for goals.