The Late-Archean Magmatic Gold Event: Toward a Non-Uniformitarian Approach.

International audienceGold is exceptionally abundant at the end of Archean. Three main steps are recognized: (1) a late TTG event at the core of calderas, producing small porphyries and gold-rich VMS deposits; (2) a sanukitoïd event, producing alkaline and felsic subvolcanic plutons with large gold hydrothermal systems, and (3) a hydrothermal/structural event. A large part of the gold mineralization may be directly related to the unique geodynamic situation, including the first subduction with two generations of gold-enriched intrusions

Acquisition of French Liaison and Related Child Errors

Although French liaison is a major topic in the fields of adult French phonology and sociolinguistics, its acquisition remains a terra incognita. Moreover, very frequent liaison consonant substitutions ("les- n-ours" instead of the adult form "les ours" with a /z/ liaison) or insertions ("papa-n-ours" instead of "papa ours") are well-known stereotypes of the French "babytalk", but their relationship with the acquisition of liaison has never been considered. Three kinds of data addressing these issues are presented. First, 300 such errors in the speech of a girl (from 2;0 to 3;6) during daily interactions will be analyzed. They suggest that /n/ is the most intrusive liaison consonant (compared with /z/ and /t/). Second, an experimentation has been carried out with 4-year old children (N=24) with the purpose of eliciting errors in words with obligatory liaisons. The results provide confirmation that /n/ is the most intrusive liaison consonant and suggest that some children are prone to use the liaison consonant they have just heard : they say more ofen "un-z-ours" (with a /z/ liaison instead of the adult /n/) after they have heard "des ours" with an adult-like /z/ liaison. Third, an experiment with three age groups [age means: 3;5 (N=15), 4;6 (N=24), 5;8 (N=15)] investigates whether implicit knowledge about probabilistic phonotactic constraints is used in segmenting ambiguous "determiner-noun" sequences. For example, subjects are hearing "determiner + non-word" sequences including a /n/ or a /z/ consonant, whose lexical and syllabic status is ambiguous : in such a sequence as "un (n)apil", one cannot hear whether /n/ is the coda liaison consonant of "un" (un apil), or whether it is the consonantal onset of the non word (un napil). Subjects are then asked to replace the singular determiner "un" with the plural determiner "des" (and vice versa when "des" + non-word sequences are presented). Responses like [dezapil] suggest that they consider /n/ to be a liaison consonant. Responses like [denapil] suggest that they view /n/ as the initial onset of the non-word "napil". Results show that responses of the youngest group do not fit phonotactic constraints (in French, /n/ is more frequent than /z/ as a word initial consonant and /z/ more frequent than /n/ as a liaison consonant) . The discussion addresses two issues : (1) What is the lexical status of liaison in the phonological representation of young children ? (2) If knowlegdge about phonotactic constraints is not available before the age of 4, how could we explain that /n/ is the most intrusive liaison consonant as early as the age of 2

Retrieval or nonretrieval strategies in mental arithmetic? An operand recognition paradigm

According to LeFevre, Sadesky, and Bisanz (1996), averaging solution latencies in order to study individuals' arithmetic strategies can result in misleading conclusions. Therefore, in addition to classical chronometric data, they collected verbal reports and challenged the assumption that adults rely systematically on retrieval of arithmetic facts from memory to solve simple addition problems. However, Kirk and Ashcraft (2001) questioned the validity of such a methodology and concluded that a more appropriate method has to be found. Thus, we developed an operand recognition paradigm that does not rely on verbal reports or on solution latencies. In accordance with LeFevre et al., we show in a first experiment that adults resort to nonretrieval strategies to solve addition problems involvingmedium numbers. However, in a second experiment, we show that high-skilled individuals can solve the same problems using a retrieval strategy. The benefits of our paradigm to the study of arithmetic strategies are discusse

Le nombre, sa genèse et son utilisation par l’enfant et l’adulte

Inexistent

Liaison acquisition, word segmentation and construction in French: A usage based account

International audienceIn the linguistic field, liaison in French is interpreted as an indicator of interactions between the various levels of language organization. The current study examines the same issue while adopting a developmental perspective. Five experiments involving children aged 2-6 years provide evidence for a developmental scenario which interrelates a number of different issues: the acquisition of phonological alternations, the segmentation of new words, the long-term stabilization of the word form in the lexicon, and the formation of item-based constructions. According to this scenario, children favour the presence of initial CV syllables when segmenting stored chunks of speech of the type word1-liaison-word2 (les arbres 'the trees' is segmented as /le/ + /zarbr/). They cope with the variation of the liaison in the input by memorizing multiple exemplars of the same word2 (/zarbr/, /narbr/). They learn the correct relations between the word1s and the word2 exemplars through exposure to the well-formed sequence (un + /narbr/, deux + /zarbr/). They generalize the relation between a word1 and a class of word2 exemplars beginning with a specific liaison consonant by integrating this information into an item-based schema (e.g. un + /nX/, deux + /zX/). This model is based on the idea that the segmentation of new words and the development of syntactic schemas are two aspects of the same process

Usage-based account of the acquisition of liaison: evidence from sensitivity to plural / singular orientation of nouns

International audienceThis study investigates whether the production and the recognition of liaison sequences in children depend on the singular/plural orientation of nouns. Certain nouns occur more frequently in the plural (e.g., arbre "tree") whereas others are found more often in the singular (e.g., arc-en-ciel "rainbow"). In the input, children more frequently encounter these plural-oriented nouns after determiners which indicate plurality (e.g., les, des, "the", deux, "two", etc.) and which are often associated with a /z/ liaison [døzarbr],"two trees". In experiment 1, 122 children (aged from 3;2 to 6;3) were asked to produce nominal phrases with either /z/ liaisons (i.e., in plural contexts like deux ours [døzurs],"two bears") or with /n/ liaisons (i.e., in singular contexts like un ours [oenurs],"one bear"). We found correlations between the plural-orientation of the nouns and (1) the probability that they will be preceded by an incorrect /z/ liaison in singular contexts (2) the probability that they will be preceded by a correct /z/ liaison in the plural context. This result was however restricted to the younger children. In experiment 2, 20 children (aged from 5;5 to 6;3) were asked to monitor target words in auditorily presented sentences. The results showed shorter responses times for singular-oriented nouns when preceded by singular determiners than when preceded by plural determiners. Conversely, plural-oriented nouns were responded to faster when preceded by a plural determiner than by a singular determiner. Results are discussed within the framework of a two-stage model of liaison acquisition recently proposed by Chevrot, Chabanal and Dugua (2007) and Chevrot, Dugua and Fayol (2009)

The Use of the Operand-Recognition Paradigm for the Study of Mental Addition in Older Adults

Objectives. Determining how individuals solve arithmetic problems is crucial for our understanding of human cognitive architecture. Elderly adults are supposed to use memory retrieval more often than younger ones. However, they might backup their retrieval by reconstructive strategies. In order to investigate this issue, we used the operand-recognition paradigm, which capitalizes on the fact that algorithmic procedures degrade the memory traces of the operands. Method. Twenty-three older adults (M = 70.4) and 23 younger adults (M = 20.0) solved easy, difficult, and medium-difficulty addition and comparison problems and were then presented with a recognition task of the operands. Results. When one-digit numbers with sums larger than 10 were involved (medium-difficulty problem), it was more difficult for younger adults to recognize the operands after addition than comparison. In contrast, in older adults, recognition times of the operands were the same after addition and comparison. Discussion. Older adults, in contrast with younger adults, are able to retrieve the results of addition problems of medium difficulty. Contrary to what was suggested, older participants do not seem to resort to backup strategies for such problems. Finally, older adults' reliance on the more efficient retrieval strategy allowed them to catch up to younger adults in terms of solution time

The use of automated procedures by older adults with high arithmetic skills during addition problem solving.

International audienceIn contrast to other cognitive abilities, arithmetic skills are known to be preserved in healthy elderly adults. In fact, they would even outperform young adults because they more often retrieve arithmetic facts from long-term memory. Nevertheless, we suggest here that the superiority of older over younger adults could also stem from the use of more efficient automated and unconscious counting procedures. We tested 35 older participants using the sign priming paradigm and selected the 18 most efficient ones, aged from 60 to 77. Sign priming are interpreted as the indicator of the pre-activation of an abstract procedure as soon as the arithmetic sign is presented. We showed that expert elderly arithmeticians behaved exactly as 26 young participants presenting the same level of arithmetic proficiency. More precisely, we showed that presenting the “+” sign 150 ms before the operands speeds up the solving process compared to a situation wherein the problem is classically presented in itswhole on the screen. Only tie problems and problems involving 0 were not subjected to these priming effects and we concluded that only these problems were solved by retrieval, either of the answer for tie problems or of a rule for + 0 problems. These results could provide new insights for the conception of training programs aiming at preserving older individuals’ arithmetical skills and, in a longer-term perspective, at maintaining their financial autonomy, which is decisive for keeping them in charge of their daily life

General and Specific Contributions of RAN to Reading and Arithmetic Fluency in First Graders: A Longitudinal Latent Variable Approach

In the present study, we opted for a longitudinal design and examined rapid automatized naming (RAN) performance from two perspectives. In a first step, we examined the structure of RAN performance from a general cognitive perspective. We investigated whether rapid naming measures (e.g., digit RAN and color RAN) reflect a mainly domain-general factor or domain-specific factors. In a second step, we examined how the best fitting RAN model was related to reading and arithmetic outcomes, assessed several months later. Finally in a third step we took a clinical perspective and investigated specific contributions of RAN measures to reading and arithmetic outcomes. While RAN has emerged as a promising predictor of reading, the relationship between RAN and arithmetic has been less examined in the past. Hundred and twenty-two first graders completed seven RAN tasks, each comprising visually familiar stimuli such as digits, vowels, consonants, dice, finger-numeral configurations, objects, and colors. Four months later the same children completed a range of reading and arithmetic tasks. From a general descriptive perspective, structural equation modeling supports a one-dimensional RAN factor in 6- to -7-year-old children. However, from a clinical perspective, our findings emphasize the specific contributions of RANs. Interestingly, alphanumeric RANs (i.e., vowel RAN) were most promising when predicting reading skills and number-specific RANs (i.e., finger-numeral configuration RAN) were most promising when predicting arithmetic fluency. The implications for clinical and educational practices will be discussed

Hippocampal spatial mechanisms relate to the development of arithmetic symbol processing in children

Understanding the meaning of abstract mathematical symbols is a cornerstone of arithmetic learning in children. Studies have long focused on the role of spatial intuitions in the processing of numerals. However, it has been argued that such intuitions may also underlie symbols that convey fundamental arithmetic concepts, such as arithmetic operators. In the present cross-sectional study, we used fMRI to investigate how and when associations between arithmetic operators and brain regions processing spatial information emerge in children from 3rd to 10th grade. We found that the mere perception of a ‘+’ sign elicited grade-related increases of spatial activity in the right hippocampus. That is, merely perceiving ‘+’ signs – without any operands – elicited enhanced hippocampal activity after around 7th grade (12–13 years old). In these children, hippocampal activity in response to a ‘+’ sign was further correlated with the degree to which calculation performance was facilitated by the preview of that sign before an addition problem, an effect termed operator-priming. Grade-related increases of hippocampal spatial activity were operation-specific because they were not observed with ‘×’ signs, which might evoke rote retrieval rather than numerical manipulation. Our study raises the possibility that hippocampal spatial mechanisms help build associations between some arithmetic operators and space throughout age and/or education