The article analyzes the neural and functional grounding of language skills as well as their emergence in hominid evolution, hypothesizing stages leading from abilities known to exist in monkeys and apes and presumed to exist in our hominid ancestors right through to modern spoken and signed languages. The starting point is the observation that both premotor area F5 in monkeys and Broca's area in humans contain a "mirror system" active for both execution and observation of manual actions, and that F5 and Broca's area are homologous brain regions. This grounded the mirror system hypothesis of Rizzolatti and Arbib (1998) which offers the mirror system for grasping as a key neural "missing link" between the abilities of our nonhuman ancestors of 20 million years ago and modern human language, with manual gestures rather than a system for vocal communication providing the initial seed for this evolutionary process. The present article, however, goes "beyond the mirror" to offer hypotheses on evolutionary changes within and outside the mirror systems which may have occurred to equip Homo sapiens with a language-ready brain. Crucial to the early stages of this progression is the mirror system for grasping and its extension to permit imitation. Imitation is seen as evolving via a so-called simple system such as that found in chimpanzees (which allows imitation of complex "object-oriented" sequences but only as the result of extensive practice) to a so-called complex system found in humans (which allows rapid imitation even of complex sequences, under appropriate conditions) which supports pantomime. This is hypothesized to have provided the substrate for the development of protosign, a combinatorially open repertoire of manual gestures, which then provides the scaffolding for the emergence of protospeech (which thus owes little to nonhuman vocalizations), with protosign and protospeech then developing in an expanding spiral. It is argued that these stages involve biological evolution of both brain and body. By contrast, it is argued that the progression from protosign and protospeech to languages with full-blown syntax and compositional semantics was a historical phenomenon in the development of Homo sapiens, involving few if any further biological changes.

What are the brain and cognitive systems that allow humans to play baseball, compute square roots, cook soufflés, or navigate the Tokyo subways? It may seem that studies of human infants and of non-human animals will tell us little about these abilities, because only educated, enculturated human adults engage in organized games, formal mathematics, gourmet cooking, or map-reading. In this chapter, we argue against this seemingly sensible conclusion. When human adults exhibit complex, uniquely human, culture-specific skills, they draw on a set of psychological and neural mechanisms with two distinctive properties: they evolved before humanity and thus are shared with other animals, and they emerge early in human development and thus are common to infants, children, and adults. These core knowledge systems form the building blocks for uniquely human skills. Without them we wouldn’t be able to learn about different kinds of games, mathematics, cooking, or maps. To understand what is special about human intelligence, therefore, we must study both the core knowledge systems on which it rests and the mechanisms by which these systems are orchestrated to permit new kinds of concepts and cognitive processes. What is core knowledge? A wealth of research on non-human primates and on human

this article were implemented using software developed by Michael Harm, whom we also thank

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In this paper, we investigated the performance of bird species recognition using neural networks with different preprocessing methods and different sets of features. Context neural network architecture was designed to embed the dynamic nature of bird songs into inputs. We devised a noise reduction algorithm and effectively applied it to enhance bird species recognition. The performance of the context neural network architecture was comparatively evaluated with linear/mel frequency cepstral coefficients and promising experimental results were achieved. 1.

Recent studies have suggested that age of acquisition (AoA) has an impact on skilled word reading. This result raises questions about previous studies in which AoA was not controlled, and about current theories in which it is not addressed. Analyses of the materials used in previous studies suggest that the observed AoA effects may have been due to other factors. We also found little evidence for an AoA effect in computational models of reading which used words that exhibit normal spelling-sound regularities. An AoA effect was observed, however, in a model in which early and late learned words did not overlap in terms of orthography or phonology. The results suggest that AOA effects occur when what is learned about early pattersn does not carry over to later ones. This condition is not characteristic of learning spelling-sound mappings but may be relevant to tasks such as learning the names for objects.

Do the neural circuits that subserve language acquisition lose plasticity as they become tuned to the maternal language? We tested adult subjects born in Korea and adopted by French families in childhood; they have become fluent in their second language and report no conscious recollection of their native language. In behavioral tests assessing their memory for Korean, we found that they do not perform better than a control group of native French subjects who have never been exposed to Korean. We also used event-related fMRI to monitor cortical activations while the Korean adoptees and native French listened to sentences spoken in the Korean, French, and in other unknown foreign languages. The adopted subjects did not show any specific activations to Korean stimuli relative to unknown languages.

ral evidence for AoA effects was weak. They pointed out that it is difficult to manipulate AoA while matching stimuli along other dimensions, because AoA is naturally correlated with such variables as imageability, length, and familiarity that also affect skilled performance. These correlations derive from an obvious source: These factors affect the ease of word learning, which is what AoA norms estimate. Thus, it is very difficult to dissociate the effects of when a word was learned (AoA) from the factors that determined when it was learned. Zevin and Seidenberg noted particular difficulties associated with standard measures of word frequency. First, differences among the most commonly used norms with respect to estimates of frequency may result in failures to equate stimuli appropriately with respect to this factor. Second, the theoretical interpretation of such frequency measures is unclear. Do they measure frequency of ex31 Copyright 2004 Psychonomic Society, Inc. This research was

at the outset that the expression “Critical Period Hypothesis ” (CPH) is used with two different meanings. The first meaning of the CPH corresponds to an empirical hypothesis according to which humans are more efficient at language learning in the first years of life. In other words, the CPH states that age of acquisition is an important predictor of ultimate proficiency: the older one starts to learn a language, the smaller the odds of reaching nativelike proficiency. The expression “critical period hypothesis ” is also sometimes used to refer to the concept that an agerelated decline in neural plasticity is the cause of increasing difficulties in language learning (Penfield & Roberts 1959). According to this second meaning, the CPH is a potential explanation of age effects on language acquisition. The two meanings must be distinguished because there may be a critical period according to the first meaning, that is, a detrimental effect of age of acquisition on ultimate proficiency in a language, even if the explanation in terms of loss of neural plasticity is wrong. In other words, an adverse effect of age of acquisition (AoA) may have other causes than irreversible neural changes (Birdsong 1999b lists some alternative explanations). Another point is worth emphasizing. In the framework of the Critical Period Hypothesis (with the second meaning), it is often assumed that the putative loss of plasticity is due to

Theories of the evolutionary origins of language must be informed by empirical and theoretical results from a variety of different fields. Complementing recent surveys of relevant work from linguistics, animal behaviour and genetics, this paper surveys the requirements on evolutionary scenarios that derive from mathematical evolutionary biology. It presents a number of simple but fundamental models from population genetics, evolutionary gametheory and social evolution theory, and evaluates their applicability to natural language. This review yields a list of required elements of evolutionary explanations in general, and of explanations for language and communication in particular. 1