American Cancer Society; Centers for Disease Control and Prevention; Swiss Re; Swiss Cancer Research foundation; Swiss Cancer League; Institut National du Cancer; La Ligue Contre le Cancer; Rossy Family Foundation; US National Cancer Institute; and the Susan G Komen Foundation.

Members of the Pirahã tribe use a "one-two-many" system of counting. I ask whether speakers of this innumerate language can appreciate larger numerosities without the benefit of words to encode them. This addresses the classic Whorfian question about whether language can determine thought. Results of numerical tasks with varying cognitive demands show that numerical cognition is clearly affected by the lack of a counting system in the language. Performance with quantities greater than three was remarkably poor, but showed a constant coefficient of variation, which is suggestive of an analog estimation process.

Centering theory, developed within computotionol linguistics, provides an account of ways in which patterns of interutteronce reference con promote the local coherence of discourse. It states thot each utterance in o coherent discourse segment contains a single semantic entity-the backword-looking center-that provides a link to the previous utteronce, ond an ordered set of entities-the forward-looking centers-that offer potential links to the next utterance. We report five reading-time experiments thot test predictions of this theory with respect to the conditions under which it is preferable to realize (refer to) on entity using a pronoun rother thon o repeated definite description or name. The experiments show that there is a single backward-looking center thot is preferentiolly realized as a pronoun, ond thot the backward-looking center is typically reolized as the grammoticol subiea of the utterance. They also provide evidence that there is a set of forward-looking centers that is ranked in terms of prominence, and that a key factor in determining prominence-surface-initial position--does not affect determination of the bockword-looking center. This provides evidence for the dissociation of the coherence processes of looking bockward and looking forward.A central issue in language processing is determining the way in which utterances fit together to form a coherent discourse. Utterances that seem equivalent in isolation, because their main propositional content is identical, may have radically different effects on discourse coherence. When an utterance is put into a discourse, the particular way in which it realizes a given propositional content determines the extent to which it coheres with the previous discourse. In this article, we examine the ways in which the structure and coherence of a discourse are influenced by the manner in which its utterances

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