Identifying the specific language abilities that separate humans from nonhuman primates has been the topic of innumerable speculations. In a recent Science article, Fitch and Hauser (2004; hereafter, F&H) argued that the hierarchy of grammars of increasing generative power described by Chomsky (e.g., 1957) provides the key for a response. At the lowest level of complexity are the finite state grammars (FSGs), which generate sequences by concatenating a set of elements (states) while following prespecified transitional probabilities. The extant literature, as F&H pointed out, indicates that nonhuman primates can master such grammars. However, according to Chomsky, human language use requires the mastery of the next level in the complexity hierarchy, termed the phrase structure grammar (PSG). "In addition to concatenating items like an FSG, a PSG can embed strings within other strings, thus creating complex hierarchical structures and long-distance dependencies" (F&H, p. 378). An instance of embedding in English is "the rat the cat ate stole the cheese," in which one relative clause ("the cat ate") is nested within the sentence ("the rat stole the cheese"). The aim of F&H's article was to show that although the abilities to master a PSG are available to all normal humans, they are not available to monkeys.In their experimental demonstration, F&H (2004) used a particular PSG, termed A n B n , where n ϭ {2,3}. This grammar generates center-embedded constructions, such as that represented in Figure 1 for n ϭ 3. The A and B elements were drawn within separate sets of eight CV syllables and were further distinguished by their acoustic characteristics. The A syllables were spoken by a female, and the B syllables by a male, so that the two classes of syllables differed by voice pitch, quality, and other particularities of the voice sources.Participants (undergraduate students, on the one hand, and cotton-top tamarins, on the other) first heard a set of sentences following the pattern AABB or AAABBB. In the subsequent test phase, they heard novel sentences, half following the same grammar (A n B n ) and half following an FSG (AB n ), which generated either ABAB or ABABAB sentences. The students were asked to state whether the pattern of each novel sound was the same as or different from the pattern heard during the familiarization phase. They scored 85% correct on this discrimination task. The performance of the tamarins was assessed through their visual orientation toward the loudspeaker, an increase in looking rate being taken as indicative that the sounds were perceived as different. Interestingly, the tamarins displayed an equivalent rate of looking to strings that violated the rules of the grammar and looking to strings that were consistent with those rules. Obviously, their failure to selectively look at the nonconsistent strings could be due to multiple causes, such as a perceptual inability to discriminate the acoustic properties of A and B syllables. In order to eliminate alternative interpretations, F&H (2004)...

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Saffran, Newport, and Aslin (1996a) found that human infants are sensitive to statistical regularities corresponding to lexical units when hearing an artificial spoken language. Two sorts of segmentation strategies have been proposed to account for this early word-segmentation ability: bracketing strategies, in which infants are assumed to insert boundaries into continuous speech, and clustering strategies, in which infants are assumed to group certain speech sequences together into units (Swingley, 2005). In the present study, we test the predictions of two computational models instantiating each of these strategies i.e., Serial Recurrent Networks: Elman, 1990; and Parser: Perruchet & Vinter, 1998 in an experiment where we compare the lexical and sublexical recognition performance of adults after hearing 2 or 10 min of an artificial spoken language. The results are consistent with Parser's predictions and the clustering approach, showing that performance on words is better than performance on part-words only after 10 min. This result suggests that word segmentation abilities are not merely due to stronger associations between sublexical units but to the emergence of stronger lexical representations during the development of speech perception processes.

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Learning and processing natural language requires the ability to track syntactic relationships between words and phrases in a sentence, which are often separated by intervening material. These nonadjacent dependencies can be studied using artificial grammar learning paradigms and structured sequence processing tasks. These approaches have been used to demonstrate that human adults, infants and some nonhuman animals are able to detect and learn dependencies between nonadjacent elements within a sequence. However, learning nonadjacent dependencies appears to be more cognitively demanding than detecting dependencies between adjacent elements, and only occurs in certain circumstances. In this review, we discuss different types of nonadjacent dependencies in language and in artificial grammar learning experiments, and how these differences might impact learning. We summarize different types of perceptual cues that facilitate learning, by highlighting the relationship between dependent elements bringing them closer together either physically, attentionally, or perceptually. Finally, we review artificial grammar learning experiments in human adults, infants, and nonhuman animals, and discuss how similarities and differences observed across these groups can provide insights into how language is learned across development and how these language‐related abilities might have evolved.

Language is a distinguishing characteristic of our species, and the course of its evolution is one of the hardest problems in science. It has long been generally considered that human speech requires a low larynx, and that the high larynx of nonhuman primates should preclude their producing the vowel systems universally found in human language. Examining the vocalizations through acoustic analyses, tongue anatomy, and modeling of acoustic potential, we found that baboons (Papio papio) produce sounds sharing the F1/F2 formant structure of the human [ɨ æ ɑ ɔ u] vowels, and that similarly with humans those vocalic qualities are organized as a system on two acoustic-anatomic axes. This confirms that hominoids can produce contrasting vowel qualities despite a high larynx. It suggests that spoken languages evolved from ancient articulatory skills already present in our last common ancestor with Cercopithecoidea, about 25 MYA.

Critical issues in letter and word priming were investigated using the novel incremental priming technique. This technique adds a parametric manipulation of prime duration (or prime intensity) to the traditional design of a fast masked priming study. By doing so, additional information on the time course and nature of priming effects can be obtained. In Experiment 1, cross-case letter priming (a-A) was investigated in both alphabetic decision (letter/non-letter classification) and letter naming. In Experiment 2, cross-case word priming was investigated in lexical decision and naming. Whereas letter priming in alphabetic decision was most strongly determined by visual overlap between prime and target, word priming in lexical decision was facilitated by both orthographic and phonological information. Orthographic activation was stronger and occurred earlier than phonological activation. In letter and word naming, in contrast, priming effects were most strongly determined by phonological/articulatory information. Differences and similarities between letter and word recognition are discussed in the light of the incremental priming data.

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