Social interaction facilitates word learning in preverbal infants: Word–object mapping and word segmentation

In natural settings, infants learn spoken language with the aid of a caregiver who explicitly provides social signals. Although previous studies have demonstrated that young infants are sensitive to these signals that facilitate language development, the impact of real-life interactions on early word segmentation and word–object mapping remains elusive. We tested whether infants aged 5–6 months and 9–10 months could segment a word from continuous speech and acquire a word–object relation in an ecologically valid setting. In Experiment 1, infants were exposed to a live tutor, while in Experiment 2, another group of infants were exposed to a televised tutor. Results indicate that both younger and older infants were capable of segmenting a word and learning a word–object association only when the stimuli were derived from a live tutor in a natural manner, suggesting that real-life interaction enhances the learning of spoken words in preverbal infants.     

Speaker variability augments phonological processing in early word learning

Infants in the early stages of word learning have difficulty learning lexical neighbors (i.e. word pairs that differ by a single phoneme), despite their ability to discriminate the same contrast in a purely auditory task. While prior work has focused on top‐down explanations for this failure (e.g. task demands, lexical competition), none has examined if bottom‐up acoustic‐phonetic factors play a role. We hypothesized that lexical neighbor learning could be improved by incorporating greater acoustic variability in the words being learned, as this may buttress still‐developing phonetic categories, and help infants identify the relevant contrastive dimension. Infants were exposed to pictures accompanied by labels spoken by either a single or multiple speakers. At test, infants in the single‐speaker condition failed to recognize the difference between the two words, while infants who heard multiple speakers discriminated between them.     

Infant speech perception bootstraps word learning

By their first birthday, infants can understand many spoken words. Research in cognitive development has long focused on the conceptual changes that accompany word learning, but learning new words also entails perceptual sophistication. Several developmental steps are required as infants learn to segment, identify and represent the phonetic forms of spoken words, and map those word forms to different concepts. We review recent research on how infants' perceptual systems unfold in the service of word learning, from initial sensitivity for speech to the learning of language-specific sound patterns. Building on a recent theoretical framework and emerging new methodologies, we show how speech perception is crucial for word learning, and suggest that it bootstraps the development of a separate but parallel phonological system that links sound to meaning.     

A real-time approach to spoken language processing in aphasia

The study is based on an on-line investigation of spoken language comprehension processes in 25 French-speaking aphasics using a syllable-monitoring task. Nonsense syllables were presented in three different conditions: context-free (embedded in strings of nonsense syllables), lexical context (where the target nonsense syllable is the initial, medial, or final syllable of real three-syllable words), and sentence context. This study builds on an earlier one that explored the relationship between the acoustic-phonetic, lexical, and sentential levels of spoken language processing in French-speaking normals and gave evidence of top-down lexical and sentential influence on syllable recognition. In the present study, aphasic patients from various diagnostic categories were classified as high (N = 13) or low (N = 12) comprehenders. The results show that low comprehending aphasics make no use of sentence information in the syllable-recognition task. As for top-down effect at the single word level that is observed in normal listeners. However, a subgroup analysis shows that the Broca's are the only high comprehending aphasics who perform in the same way as normal listeners; this sets them apart from the anomics and conduction aphasics.     

新词词素熟悉性影响视觉词切分线索在新词学习中的促进作用

为考察词素熟悉性是否会影响视觉词切分线索在新词学习中的作用,本研究中新词由两类假词构成：第一类假词由两个高频字（高熟悉性词素）组成,第二类假词由两个低频字（低熟悉性词素）组成。实验采用学习-测试范式,将新词镶嵌在句子中供大学生被试阅读。结果发现,相比由低熟悉性词素构成的新词,词间空格在由高熟悉词素构成的新词中起到的促进作用更大。表明在汉语阅读过程中,词素熟悉性可能作为一种线索参与词切分。     

Cross-modal working memory binding and L1-L2 word learning

The ability to create temporary binding representations of information from different sources in working memory has recently been found to relate to the development of monolingual word recognition in children. The current study explored this possible relationship in an adult word-learning context. We assessed whether the relationship between cross-modal working memory binding and lexical development would be observed in the learning of associations between unfamiliar spoken words and their semantic referents, and whether it would vary across experimental conditions in first- and second-language word learning. A group of English monolinguals were recruited to learn 24 spoken disyllable Mandarin Chinese words in association with either familiar or novel objects as semantic referents. They also took a working memory task in which their ability to temporarily bind auditory-verbal and visual information was measured. Participants’ performance on this task was uniquely linked to their learning and retention of words for both novel objects and for familiar objects. This suggests that, at least for spoken language, cross-modal working memory binding might play a similar role in second language-like (i.e., learning new words for familiar objects) and in more native-like situations (i.e., learning new words for novel objects). Our findings provide new evidence for the role of cross-modal working memory binding in L1 word learning and further indicate that early stages of picture-based word learning in L2 might rely on similar cognitive processes as in L1.     

Word order priming in written and spoken sentence production

An experiment is reported that showed priming of the word order of auxiliary verb and past participle in Dutch subordinate clauses, both in speaking and in writing. Participants completed sentence fragments to full sentences. Prime sentence fragments were constrained so as to be completed with only one possible word order. Target sentence fragments, presented immediately after the prime fragments, could be completed with the same word order as that of the prime and an alternative order with the two words exchanged. Significant priming effects were obtained, so that the same word orders tended to be used in prime and target. We interpret this as evidence for a distinct process of constituent structure linearization during sentence production, which serves to ensure the fluency of speech and writing.     

The effects of processing requirements on neurophysiological responses to spoken sentences

Ten English speaking subjects listened to sentences that varied in sentential constraint (i.e., the degree to which the context of a sentence predicts the final word of that sentence) and event-related potentials (ERPs) were recorded during the presentation of the final word of each sentence. In the Control condition subjects merely listened to the sentences. In the Orthographic processing condition subjects merely listened to the sentences. In the Orthographic processing condition subjects decided, following each sentence, whether a given letter had been present in the final word of the preceding sentence. In the Phonological processing condition the subjects judged whether a given speech sound was contained in the terminal word. In the Semantic processing condition subjects determined whether the final word was a member of a given semantic category. A previous finding in the visual modality that the N400 component was larger in amplitude for low constraint sentence terminations than for high was extended to the auditory modality. It was also found that the amplitude of a N200-like response was similarly responsive to contextual constraint. The hypothesis that N400 amplitude would vary significantly with the depth of processing of the terminal word was not supported by the data. The "N200" recorded in this language processing context showed the classic frontocentral distribution of the N200. The N400 to spoken sentences had a central/centroparietal distribution similar to the N400 in visual modality experiments. It is suggested that the N400 obtained in these sentence contexts reflects an automatic semantic processing of words that occurs even when semantic analysis is not required to complete a given task. The cooccurrence and topographical dissimilarity of the "N200" and N400 suggest that the N400 may not be a delayed or a generic N200.     

All words are not created equal: expectations about word length guide infant statistical learning

Infants have been described as ‘statistical learners’ capable of extracting structure (such as words) from patterned input (such as language). Here, we investigated whether prior knowledge influences how infants track transitional probabilities in word segmentation tasks. Are infants biased by prior experience when engaging in sequential statistical learning? In a laboratory simulation of learning across time, we exposed 9- and 10-month-old infants to a list of either disyllabic or trisyllabic nonsense words, followed by a pause-free speech stream composed of a different set of disyllabic or trisyllabic nonsense words. Listening times revealed successful segmentation of words from fluent speech only when words were uniformly disyllabic or trisyllabic throughout both phases of the experiment. Hearing trisyllabic words during the pre-exposure phase derailed infants’ abilities to segment speech into disyllabic words, and vice versa. We conclude that prior knowledge about word length equips infants with perceptual expectations that facilitate efficient processing of subsequent language input.     

Incidental formation of episodic associations: The importance of sentential context

The influence of relevant semantic context on the incidental formation of episodic associations between words was probed in two experiments. In Experiment 1, we examined the influence of associations formed incidentally between unrelated words presented either in isolation or embedded in a sentential context on subsequent explicit paired-associate leaning tested by cued recall. The results of Experiment 1 showed that the cued-recall rate of words studied in sentential context was higher than that of words co-occurring in isolated pairs. A subsequent single-items recognition test showed equal item memory for words studied in sentences than for words studied in isolated pairs, suggesting that the sentential context effect in cued recall indeed reflected stronger associations between paired words rather than better memory for single words. In Experiment 2, we ruled out memory for the entire sentence as an alternative explanation for the results of Experiment 1. We suggest two possible mechanisms to account for this advantage: First, pairs embedded in a sentence undergo semantic elaboration that might lead to the incidental formation of an association between them. Second, words embedded in a sentence enjoy the conjoint activation of compatible semantic features, a fact that may also facilitate the formation of an episodic association between them. The implications of these results for computational models using word representations based on co-occurrence data are discussed.     

The effects of talker familiarity on spoken word identification in younger and older listeners

The present study was designed to examine age differences in the ability to use voice information acquired intentionally (Experiment 1) or incidentally (Experiment 2) as an aid to spoken word identification. Following both implicit and explicit voice learning, participants were asked to identify novel words spoken either by familiar talkers (ones they had been exposed to in the training phase) or by 4 unfamiliar voices. In both experiments, explicit memory for talkers' voices was significantly lower in older than in young listeners. Despite this age-related decline in voice recognition, however, older adults exhibited equivalent, and in some cases greater, benefit than young listeners from having words spoken by familiar talkers. Implications of the findings for age-related changes in explicit versus implicit memory systems are discussed.     

The locus of the effects of sentential-semantic context in spoken-word processing

Models of word recognition differ with respect to where the effects of sentential-semantic context are to be located. Using a crossmodal priming technique, this research investigated the availability of lexical entries as a function of stimulus information and contextual constraint. To investigate the exact locus of the effects of sentential contexts, probes that were associatively related to contextually appropriate and inappropriate words were presented at various positions before and concurrent with the spoken word. The results show that sentential contexts do not preselect a set of contextually appropriate words before any sensory information about the spoken word is available. Moreover, during lexical access, defined here as the initial contact with lexical entries and their semantic and syntactic properties, both contextually appropriate and inappropriate words are activated. Contextual effects are located after lexical access, at a point in time during word processing where the sensory input by itself is still insufficiently informative to disambiguate between the activated entries. This suggests that sentential-semantic contexts have their effects during the process of selecting one of the activated candidates for recognition.     

Rapid Gains in Speed of Verbal Processing by Infants in the 2nd Year

Infants improve substantially in language ability during their 2nd year. Research on the early development of speech production shows that vocabulary begins to expand rapidly around the age of 18 months. During this period, infants also make impressive gains in understanding spoken language. We examined the time course of word recognition in infants from ages 15 to 24 months, tracking their eye movements as they looked at pictures in response to familiar spoken words. The speed and efficiency of verbal processing increased dramatically over the 2nd year. Although 15-month-old infants did not orient to the correct picture until after the target word was spoken, 24-month-olds were significantly faster, shifting their gaze to the correct picture before the end of the spoken word. By 2 years of age, children are progressing toward the highly efficient performance of adults, making decisions about words based on incomplete acoustic information.     

Influences of high and low variability on infant word recognition

Although infants begin to encode and track novel words in fluent speech by 7.5 months, their ability to recognize words is somewhat limited at this stage. In particular, when the surface form of a word is altered, by changing the gender or affective prosody of the speaker, infants begin to falter at spoken word recognition. Given that natural speech is replete with variability, only some of which determines the meaning of a word, it remains unclear how infants might ever overcome the effects of surface variability without appealing to meaning. In the current set of experiments, consequences of high and low variability are examined in preverbal infants. The source of variability, vocal affect, is a common property of infant-directed speech with which young learners have to contend. Across a series of four experiments, infants' abilities to recognize repeated encounters of words, as well as to reject similar-sounding words, are investigated in the context of high and low affective variation. Results point to positive consequences of affective variation, both in creating generalizable memory representations for words, but also in establishing phonologically precise memories for words. Conversely, low variability appears to degrade word recognition on both fronts, compromising infants' abilities to generalize across different affective forms of a word and to detect similar-sounding items. Findings are discussed in the context of principles of categorization that may potentiate the early growth of a lexicon.     

Sentential context and the interpretation of unambiguous words

Two experiments were carried out in order to investigate how the linguistic context (in the form of a sentence) facilitates the interpretation of unambiguous words. Experiment I established that if a sentential context as a whole is sufficient to evoke an inference that calls to mind a particular aspect of a word's meaning, the presence of a verb with appropriate selectional restrictions does not enhance the process. Experiment II showed that when no other cues are provided within a sentence, both verbs and adjectives are effective in enhancing a specific aspect of the meaning of a word. These findings were taken to support the hypothesis that in understanding a sentence, people instantiate particular aspects of the meanings of words in order to construct specific interpretations, and linguistic context guides this process of selection.     

Or cues knowledge of alternatives: Evidence from priming

Recent research has determined that word meanings can instantly influence the meaning and distribution of other words in the sentence. Here, we manipulated basic carrier sentences with the disjunction or linking two nouns that were either filling the same thematic role or not, and were either semantically related or not. Though previous research has shown that one word can prime a semantically related word even in a sentential context, we predicted that if or cues knowledge about contextually‐relevant alternatives, priming for semantic relatives will only obtain when those words also fill the same thematic role. These predictions were confirmed, as self‐paced reading times of the second alternative in the sentence were faster only when the two alternatives shared the same thematic role and semantic category, suggesting that disjunction words like or function similarly to verbs, which cue knowledge about expected argument structure and sense depending on sentential context. The relevance of these findings for basic reasoning phenomena (i.e., the subadditivity effect) is also discussed.     

Retrieval-based illusory recollections: Why study-test contextual changes impair source memory

Illusory source recollections can be manufactured purely by the conditions at retrieval. At encoding, individuals listened to words spoken by a male or a female voice and later, at retrieval, determined who initially had spoken the test word or whether it was a new word. In Experiment 1, individuals were instructed during the memory test to make a response of male or female only if they clearly recollected the speaker presenting the item during encoding and to respond don't remember otherwise. Presenting test words with the same voice (match condition) as the one that had presented the word at encoding, a different voice (mismatch condition), or no test voice had no effect on the rate of responding don't remember. Instead, matching and mismatching test voices created illusory recollections that were consistent with the test voice. Experiment 2 yielded similar results with a remember/know source test. In this article, a theory is proposed that explains the illusory recollection effects, and a multinomial model and procedure are used to separate and measure the contributions of source discrimination and illusory recollections to performance.     

Infants' sensitivity to allophonic cues for word segmentation

A series of four experiments was conducted to determine whether English-learning infants can use allophonic cues to word boundaries to segment words from fluent speech. Infants were familiarized with a pair of two-syllable items, such as nitrates and night rates and then were tested on their ability to detect these same words in fluent speech passages. The presence of allophonic cues to word boundaries did not help 9-month-olds to distinguish one of the familiarized words from an acoustically similar foil. Infants familiarized with nitrates were just as likely to listen to a passage about night rates as they were to listen to one about nitrates. Nevertheless, when the passages contained distributional cues that favored the extraction of the familiarized targets, 9-month-olds were able to segment these items from fluent speech. By the age of 10.5 months, infants were able to rely solely on allophonic cues to locate the familiarized target words in passages. We consider what implications these findings have for understanding how word segmentation skills develop.     

Twelve-month-olds privilege words over other linguistic sounds in an associative learning task

We examined whether 12-month-old infants privilege words over other linguistic stimuli in an associative learning task. Sixty-four infants were presented with sets of either word–object, communicative sound–object, or consonantal sound–object pairings until they habituated. They were then tested on a ‘switch’ in the sound to determine whether they were able to associate the word and/or sound with the novel objects. Infants associated words, but not communicative sounds or consonantal sounds, with novel objects. The results demonstrate that infants exhibit a preference for words over other linguistic stimuli in an associative word learning task. This suggests that by 12 months of age, infants have developed knowledge about the nature of an appropriate sound form for an object label and will privilege this form as an object label.     

Unblocking memory through directed forgetting

The ability to remember an item can be blocked, or negatively primed, by exposure to related items. For example, ALLERGY is less likely to be generated given the word fragment A_L_ _GY if one is first exposed to ANALOGY. We examined whether this memory blocking effect is influenced by list-method directed forgetting. A total of 144 participants learned two lists of items, each consisting of words that were designed to negatively prime performance on a subsequent word fragment completion task. Participants who were told to forget List 1 before learning List 2 suffered significantly less memory blocking owing to the negative primes from List 1 than participants who were told to remember List 1. These results suggest that directed forgetting can modify the memory blocking effect by affecting the accessibility of information in memory.