How do people know as much as they do with as little information as they get? The problem takes many forms; learning vocabulary from text is an especially dramatic and convenient case for research. A new general theory of acquired similarity and knowledge representation, latent semantic analysis (LSA), is presented and used to successfully simulate such learning and several other psycholinguistic phenomena. By inducing global knowledge indirectly from local co-occurrence data in a large body of representative text, LSA acquired knowledge about the full vocabulary of English at a comparable rate to schoolchildren. LSA uses no prior linguistic or perceptual similarity knowledge; it is based solely on a general mathematical learning method that achieves powerful inductive effects by extracting the right number of dimensions (e.g., 300) to represent objects and contexts. Relations to other theories, phenomena, and problems are sketched. Prologue "How much do we know at any time? Much more, or so I believe, than we know we know!" —Agatha Christie, The Moving Finger A typical American seventh grader knows the meaning of

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.

Did evolution endow the human brain with a predisposition to represent and acquire knowledge about numbers? Although the parietal lobe...

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Abstract not found

Graded interference effects were tested in a naming task, in parallel for objects and actions. Participants named either object or action pictures presented in the context of other pictures (blocks) that were either semantically very similar, or somewhat semantically similar or semantically dissimilar. We found that naming latencies for both object and action words were modulated by the semantic similarity between the exemplars in each block, providing evidence in both domains of graded semantic effects. Graded Semantic Effects in Object and Action Naming Miller and Fellbaum (1991) wrote: "When psychologists think about the organization of lexical memory it is nearly always the organization of nouns that they have in mind" (p.214). Even more specifically, we may add, often it is nouns referring to objects that we have in mind. Although the object-noun domain is certainly relevant to studies of lexical memory, it only represents part of adults' lexical knowledge; theories and tools deve...

We study the allocation of time across decision problems. If a decision-maker (1) has noisy estimates of value, (2) improves those estimates the longer he or she analyzes a choice problem, and (3) allocates time optimally, then the decision-maker should spend less time choosing when the difference in value between two options is relatively large. To test this prediction we ask subjects to make 27 binary incentive-compatible intertemporal choices, and measure response time for each decision. Our time allocation model explains 54 % of the variance in average decision time. These results support the view that decisionmaking is a cognitively costly activity that uses time as an input allocated according to cost-benefit principles.

Recent work has brought attention to the phenomenon of memory-based sequence smoothing. In this research, subjects study a sequence of random numbers and then recall them in their correct order. Previous findings suggest that subjects tend to remember a smoothed version of the original sequence (Anderson 1999). The smoothing phenomenon, to be covered in depth later, can be conceptualized as drift toward a local mean, such that subjects ’ recall of a number at a certain position is influenced by the numbers in adjacent positions. The purpose of the present study was to determine the relationship between memory-based sequence smoothing and representation. It is hypothesized that experimental conditions that encourage non-categorical, magnitude-based encoding will display a greater degree of smoothing than will conditions that encourage categorical encoding. I will review the evidence supporting memory-based sequence smoothing, along with the literature on mental representation and numerical cognition. I will also discuss how the theories of numerical cognition explain smoothing and how smoothing might play an adaptive role in numerical cognition.

this article should be addressed In Stanislas Deraerie, Laboratoire de Sciences Cognitives et Psycholinguistique, 54 Bd Raspall, F-75270 Paris Ctdex 06, France

What is the nature of our mental representation of quantity? We find that human adults show no performance cost of comparing numerosities across vs. within visual and auditory stimulus sets, or across vs. within simultaneous and sequential sets. In addition, reaction time and performance in such tasks are determined by the ratio of the numerosities to be compared; absolute set size has no effect. These findings suggest that modality-specific stimulus properties undergo a non-iterative transformation into representations of quantity that are independent of the modality or format of the stimulus. q 2002 MIT Published by Elsevier Science B.V. All rights reserved.