Acquisition of Nonadjacent Phonological Dependencies in the Native Language During the First Year of Life

Languages instantiate many different kinds of dependencies, some holding between adjacent elements and others holding between nonadjacent elements. In the domain of phonology–phonotactics, sensitivity to adjacent dependencies has been found to appear between 6 and 10 months. However, no study has directly established the emergence of sensitivity to nonadjacent phonological dependencies in the native language. The present study focuses on the emergence of a perceptual Labial‐Coronal (LC) bias, a dependency involving two nonadjacent consonants. First, Experiment 1 shows that a preference for monosyllabic consonant‐vowel‐consonant LC words over CL (Coronal‐Labial) words emerges between 7 and 10 months in French‐learning infants. Second, two experiments, presenting only the first or last two phonemes of the original stimuli, establish that the LC bias at 10 months cannot be explained by adjacent dependencies or by a preference for more frequent coronal consonants ( Experiment 2a & b ). At 7 months, by contrast, infants appear to react to the higher frequency of coronal consonants ( Experiment 3a & b ). The present study thus demonstrates that infants become sensitive to nonadjacent phonological dependencies between 7 and 10 months. It further establishes a change between these two ages from sensitivity to local properties to nonadjacent dependencies in the phonological domain.     

Statistical inference for oscillation processes

ABSTRACT

A new model for time series with a specific oscillation pattern is proposed. The model consists of a hidden phase process controlling the speed of polling and a nonparametric curve characterizing the pattern, leading together to a generalized state space model. Identifiability of the model is proved and a method for statistical inference based on a particle smoother and a nonparametric EM algorithm is developed. In particular, the oscillation pattern and the unobserved phase process are estimated. The proposed algorithms are computationally efficient and their performance is assessed through simulations and an application to human electrocardiogram recordings.     

Confounding adjustment methods for multi-level treatment comparisons under lack of positivity and unknown model specification

Imbalances in covariates between treatment groups are frequent in observational studies and can lead to biased comparisons. Various adjustment methods can be employed to correct these biases in the context of multi-level treatments (> 2). Analytical challenges, such as positivity violations and incorrect model specification due to unknown functional relationships between covariates and treatment or outcome, may affect their ability to yield unbiased results. Such challenges were expected in a comparison of fire-suppression interventions for preventing fire growth. We identified the overlap weights, augmented overlap weights, bias-corrected matching and targeted maximum likelihood as methods with the best potential to address those challenges. A simple variance estimator for the overlap weight estimators that can naturally be combined with machine learning is proposed. In a simulation study, we investigated the performance of these methods as well as those of simpler alternatives. Adjustment methods that included an outcome modeling component performed better than those that focused on the treatment mechanism in our simulations. Additionally, machine learning implementation was observed to efficiently compensate for the unknown model specification for the former methods, but not the latter. Based on these results, we compared the effectiveness of fire-suppression interventions using the augmented overlap weight estimator.     

Random walk Green kernels in the neutral Moran model conditioned on survivors at a random time to origin

In the theory of finite discrete-time birth and death chains with absorbing endpoint boundaries, the evaluation of both additive and multiplicative path functionals is made possible by their Green and λ–potential kernels. These computations are addressed in the context of such Markov chains. The application to the neutral Moran model of population genetics yields first hitting and return times. A neutral Moran bridge model, forward and backward in time, for a given total number x of survivors of a single common ancestor at some random time T to the origin of times, yields the age of a mutant allele currently observed to have x copies of itself. This forward theory of age, made possible by Green kernels, is comparable to Watterson’s backward theory of age, which makes use of the reversibility of the Moran chain.     

The probability of ties with scoring methods: Some results

The main flaw of the Condorcet method is that a Condorcet winner does not always exist (when there is a top cycle). Moreover, in some cases, all candidates are contained in one cycle and, therefore, a society or committee using the Condorcet method risks to face a severe indeterminacy. An indeterminacy can also happen when using other methods: for example the Borda method, plurality voting or any scoring method; but the origin of the indeterminacy is completely different. It happens when all candidates are tied. We study the probability that all candidates are tied when using a scoring method. We show that it is equivalent to some random walk problems. Some analytical and numerical results show that, under the assumptions underlying our study, the probability is very small and decreases when the number of voters or candidates increases. Received: 18 December 1998/Accepted: 17 March 2000     

Better Processing of Consonantal Over Vocalic Information in Word Learning at 16 Months of Age

Previous research using the name‐based categorization task has shown that 20‐month‐old infants can simultaneously learn 2 words that only differ by 1 consonantal feature but fail to do so when the words only differ by 1 vocalic feature. This asymmetry was taken as evidence for the proposal that consonants are more important than vowels at the lexical level. This study explores this consonant‐vowel asymmetry in 16‐month‐old infants, using an interactive word learning task. It shows that the pattern of the 16‐month‐olds is the same as that of the 20‐month‐olds. Infants succeeded with 1‐feature consonantal contrasts (either place or voicing) but were at chance level with 1‐feature vocalic contrasts (either place or height). These results thus contribute to a growing body of evidence establishing, from early infancy to adulthood, that consonants and vowels have different roles in lexical acquisition and processing.     

How Risk Disciplines Pre-Commitment

This paper studies the entry strategies of firms on risky markets. We focus on markets where demand is affine and cost is linear; moreover, the demand includes a normally distributed random variable. In such a model, we show that the leader’s strategy changes with the level of market risk even when firms are risk neutral. Therefore, the availability of future information for a Stackelberg follower has a feedback effect on the leader’s strategy. We also show that compared with traditional markets with no risk, the basic trade-off between flexibility and pre-commitment is only slightly changed in the qualitative game where firms are free to choose when to enter the market.

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