Headturn Preference Procedure Research Articles

Was that my name? Infants' listening in conversational multi-talker backgrounds.

This study tested infants' ability to segregate target speech from a background of ecologically valid multi-talker speech at a 10 dB SNR. Using the Headturn Preference Procedure, 72 English-learning 5-, 9-, and 12-month-old monolinguals were tested on their ability to detect and perceive their own name. At all three ages infants were able to detect the presence of the target speech, but only at 9 months did they show sensitivity to the phonetic details that distinguished their own name from other names. These results extend previous findings on infants' speech perception in noise to more naturalistic forms of background speech.

The longevity of statistical learning: When infant memory decays, isolated words come to the rescue.

Research over the past 2 decades has demonstrated that infants are equipped with remarkable computational abilities that allow them to find words in continuous speech. Infants can encode information about the transitional probability (TP) between syllables to segment words from artificial and natural languages. As previous research has tested infants immediately after familiarization, infants' ability to retain sequential statistics beyond the immediate familiarization context remains unknown. Here, we examine infants' memory for statistically defined words 10 min after familiarization with an Italian corpus. Eight-month-old English-learning infants were familiarized with Italian sentences that contained 4 embedded target words-2 words had high internal TP (HTP, TP = 1.0) and 2 had low TP (LTP, TP = .33)-and were tested on their ability to discriminate HTP from LTP words using the Headturn Preference Procedure. When tested after a 10-min delay, infants failed to discriminate HTP from LTP words, suggesting that memory for statistical information likely decays over even short delays (Experiment 1). Experiments 2-4 were designed to test whether experience with isolated words selectively reinforces memory for statistically defined (i.e., HTP) words. When 8-month-olds were given additional experience with isolated tokens of both HTP and LTP words immediately after familiarization, they looked significantly longer on HTP than LTP test trials 10 min later. Although initial representations of statistically defined words may be fragile, our results suggest that experience with isolated words may reinforce the output of statistical learning by helping infants create more robust memories for words with strong versus weak co-occurrence statistics. (PsycINFO Database Record

Emergence of Japanese infants' prosodic preferences in infant-directed vocabulary.

The article examines the role of infant-directed vocabulary (IDV) in infants language acquisition, specifically addressing the question of whether IDV forms that are not prominent in adult language may nonetheless be useful to the process of acquisition. Japanese IDV offers a good test case, as IDV characteristically takes a bisyllabic H(eavy)-L(ight) form that is rare in adult speech. In 5 experiments using the Headturn Preference Procedure (HPP), 8- to 10-month-old Japanese infants, but not 4- to 6-month-olds, were found to show a preference for bisyllabic H-L words over other types of words. These results demonstrate (a) that infants may develop a preference for a dominant prosodic form based on infant-directed speech, even when it is not a prominent characteristic of adult language; and perhaps more importantly, and (b) that infant-directed speech may provide a boost for a feature that could be useful for infants' acquisition of language even when it not prominent in adult language. (PsycINFO Database Record

Developing knowledge of nonadjacent dependencies.

Characterizing the nature of linguistic representations and how they emerge during early development is a central goal in the cognitive science of language. One area in which this development plays out is in the acquisition of dependencies-relationships between co-occurring elements in a word, phrase, or sentence. These dependencies often involve multiple levels of representation and abstraction, built up as infants gain experience with their native language. The authors used the Headturn Preference Procedure to systematically investigate the early acquisition of 1 such dependency, the agreement between a subject and verb in French, at 6 different ages between 14 and 24 months. The results reveal a complex developmental trajectory that provides the first evidence that infants might indeed progress through distinct stages in the acquisition of this nonadjacent dependency. The authors discuss how changes in general cognition and representational knowledge (from reflecting surface statistics to higher-level morphological features) might account for their findings. These findings highlight the importance of studying language acquisition at close time intervals over a substantial age range. (PsycINFO Database Record

An Exploration of Rhythmic Grouping of Speech Sequences by French- and German-Learning Infants.

Rhythm in music and speech can be characterized by a constellation of several acoustic cues. Individually, these cues have different effects on rhythmic perception: sequences of sounds alternating in duration are perceived as short-long pairs (weak-strong/iambic pattern), whereas sequences of sounds alternating in intensity or pitch are perceived as loud-soft, or high-low pairs (strong-weak/trochaic pattern). This perceptual bias—called the Iambic-Trochaic Law (ITL)–has been claimed to be an universal property of the auditory system applying in both the music and the language domains. Recent studies have shown that language experience can modulate the effects of the ITL on rhythmic perception of both speech and non-speech sequences in adults, and of non-speech sequences in 7.5-month-old infants. The goal of the present study was to explore whether language experience also modulates infants’ grouping of speech. To do so, we presented sequences of syllables to monolingual French- and German-learning 7.5-month-olds. Using the Headturn Preference Procedure (HPP), we examined whether they were able to perceive a rhythmic structure in sequences of syllables that alternated in duration, pitch, or intensity. Our findings show that both French- and German-learning infants perceived a rhythmic structure when it was cued by duration or pitch but not intensity. Our findings also show differences in how these infants use duration and pitch cues to group syllable sequences, suggesting that pitch cues were the easier ones to use. Moreover, performance did not differ across languages, failing to reveal early language effects on rhythmic perception. These results contribute to our understanding of the origin of rhythmic perception and perceptual mechanisms shared across music and speech, which may bootstrap language acquisition.

Infant auditory short-term memory for non-linguistic sounds

This research explores auditory short-term memory (STM) capacity for non-linguistic sounds in 10-month-old infants. Infants were presented with auditory streams composed of repeating sequences of either 2 or 4 unique instruments (e.g., flute, piano, cello; 350 or 700ms in duration) followed by a 500-ms retention interval. These instrument sequences either stayed the same for every repetition (Constant) or changed by 1 instrument per sequence (Varying). Using the head-turn preference procedure, infant listening durations were recorded for each stream type (2- or 4-instrument sequences composed of 350- or 700-ms notes). Preference for the Varying stream was taken as evidence of auditory STM because detection of the novel instrument required memory for all of the instruments in a given sequence. Results demonstrate that infants listened longer to Varying streams for 2-instrument sequences, but not 4-instrument sequences, composed of 350-ms notes (Experiment 1), although this effect did not hold when note durations were increased to 700ms (Experiment 2). Experiment 3 replicates and extends results from Experiments 1 and 2 and provides support for a duration account of capacity limits in infant auditory STM.

Infants' use of baby sign to extract unfamiliar words from the speech stream

The ability to extract words from fluent speech is crucial for language learning. Infants use environmental information to aid in this process. Baby sign is a popular trend that may aid an infant in segmenting the speech stream and extracting words. A study designed to test the effects of baby sign to aid infants in extracting words from the speech stream was conducted. Six-month-old infants were shown videos of passages where either the speaker's face, hands (sign only), or both (face and signs) were visible. A head-turn preference procedure was used to test infants' ability to identify familiarised nonsense words versus control nonsense words. The resulting data are the first to demonstrate that prior exposure to baby sign can aid an infant in extracting unfamiliar words from fluent speech and six-month-old infants can use a speaker's face as a cue to extract words from speech.

Early Speech Segmentation in French-learning Infants: Monosyllabic Words versus Embedded Syllables.

Lexical acquisition relies on many mechanisms, one of which corresponds to segmentation abilities, that is, the ability to extract word forms from fluent speech. This ability is important since words are rarely produced in isolation even when talking to infants. The present study explored whether young French-learning infants segment from fluent speech the rhythmic unit of their native language, the syllable. Using the Headturn Preference Procedure and the passage word order, we explored whether these infants can segment monosyllabic words (at 6 and 8 months), syllables embedded in bisyllabic words (at 6 months) and bisyllabic words (at 6 months). Our results bring direct evidence in support of the early rhythmic segmentation hypothesis, by establishing syllabic segmentation both for monosyllabic words and embedded syllables at 6 months, while failing to find segmentation of bisyllabic words at the same age. They also indirectly extend to French previously reported effects of coarticulation, acoustic variation and infant-directed speech on segmentation found in English. Therefore, our study contributes to a better understanding of the similarities and differences in early segmentation across languages, and thus to a better understanding of the mechanisms underlying segmentation.

Utterance‐Final Lengthening Is Predictive of Infants’ Discrimination of English Accents

Infants in their first year manifest selective patterns of discrimination between languages and between accents of the same language. Prosodic differences are held to be important in whether languages can be discriminated, together with the infant's familiarity with one or both of the accents heard. However, the nature of the prosodic cues that actually facilitate infant discrimination has not been directly examined. We analyzed the accent discrimination of 5‐ and 7‐month‐old British English infants, looking for durational features that could predict a range of discrimination results using the Headturn Preference Procedure. We previously found that both 5‐ and 7‐month‐olds based in Plymouth could discriminate Plymouth‐accented and Welsh‐accented English, while 5‐month‐olds could not discriminate Welsh‐accented and Scottish‐accented English. Most surprisingly, 7‐month‐olds failed to discriminate Plymouth‐accented and French‐accented English. From half of all utterances used in these four experiments, we calculated a range of durational metrics, both globally across utterances and locally at utterance‐final edges. Utterance‐edge metrics were the relative duration of the final consonant+vowel interval (nfinalCV) and the final vowel alone (nfinalV). Separately for 5‐ and 7‐month‐olds, we determined the difference in scores for all durational metrics between: (a) familiar training and novel test utterances and (b) familiar test and novel test utterances. Regression analyses showed unique predictors of discrimination. For 5‐month‐olds, the predictor was the difference in nfinalCV between familiar training and novel test utterances. For 7‐month‐olds, the predictor was the difference in finalV between familiar test and novel test utterances. This demonstrates an early sensitivity to precisely those localized timing features that are useful across languages for segmentation. We therefore predict that similar sensitivity should be shown in infants of other language backgrounds.

Infant-directed speech reduces English-learning infants preference for strong/weak versus weak/strong words

Mounting evidence suggests that infant-directed speech (IDS) facilitates aspects of language acquisition. An important milestone of English-learning infants' language acquisition is encoding the predominant stress-initial rhythmic structure of English, which 9-month-olds have demonstrated by showing a looking-time preference for lists of strong/weak words (e.g., doctor) versus weak/strong words (e.g., guitar) (Jusczyk et al., 1993). We tested for this preference in 48 9-month-olds using the headturn preference procedure. Twenty-four infants were presented with the words using IDS, and 24 were presented with adult-directed speech (ADS). Infants were presented with a visual display of a blinking light on one of two (left and right) monitors. When they oriented toward the monitor, a list was presented from behind that monitor until they looked away for more than 2 s. They were presented with lists of weak/strong words for half the trials and strong/weak words for the other half in quasi-random order. A repeated-measures AVOVA revealed a statistically significant interaction between word-type preference and speech condition. To our surprise, only infants in the ADS condition showed a preference strong/weak words. The findings raise the possibility that rhythmic properties of words may be more difficult for infants to encode in IDS than ADS.

Implicit meaning in 18‐month‐old toddlers

A substantial body of evidence demonstrates that infants understand the meaning of spoken words from as early as 6months. Yet little is known about their ability to do so in the absence of any visual referent, which would offer diagnostic evidence for an adult-like, symbolic interpretation of words and their use in language mediated thought. We used the head-turn preference procedure to examine whether infants can generate implicit meanings from word forms alone as early as 18months of age, and whether they are sensitive to meaningful relationships between words. In one condition, toddlers were presented with lists of words taken from the same taxonomic category (e.g. animals or body parts). In a second condition, words taken from two other categories (e.g. clothes and food items) were interleaved within the same list. Listening times were found to be longer in the related-category condition than in the mixed-category condition, suggesting that infants extract the meaning of spoken words and are sensitive to the semantic relatedness between these words. Our results show that infants have begun to construct the rudiments of a semantic system based on taxonomic relations even before they enter a period of accelerated vocabulary growth.

Perception of Speech Modulation Cues by 6-Month-Old Infants

The capacity of 6-month-old infants to discriminate a voicing contrast (/aba/-/apa/) on the basis of amplitude modulation (AM) cues and frequency modulation (FM) cues was evaluated. Several vocoded speech conditions were designed to either degrade FM cues in 4 or 32 bands or degrade AM in 32 bands. Infants were familiarized to the vocoded stimuli for a period of either 1 or 2 min. Vocoded speech discrimination was assessed using the head-turn preference procedure. Infants discriminated /aba/ from /apa/ in each condition; however, familiarization time was found to influence strongly infants' responses (i.e., their preference for novel vs. familiar stimuli). Six-month-old infants do not require FM cues and can use the slowest (< 16 Hz) AM cues to discriminate voicing. Moreover, 6-month-old infants can use AM cues extracted from only 4 broad-frequency bands to discriminate voicing.

Early syllabic segmentation of fluent speech by infants acquiring French.

Word form segmentation abilities emerge during the first year of life, and it has been proposed that infants initially rely on two types of cues to extract words from fluent speech: Transitional Probabilities (TPs) and rhythmic units. The main goal of the present study was to use the behavioral method of the Headturn Preference Procedure (HPP) to investigate again rhythmic segmentation of syllabic units by French-learning infants at the onset of segmentation abilities (around 8 months) given repeated failure to find syllabic segmentation at such a young age. The second goal was to explore the interaction between the use of TPs and syllabic units for segmentation by French-learning infants. The rationale was that decreasing TP cues around target syllables embedded in bisyllabic words would block bisyllabic word segmentation and facilitate the observation of syllabic segmentation. In Experiments 1 and 2, infants were tested in a condition of moderate TP decrease; no evidence of either syllabic or bisyllabic word segmentation was found. In Experiment 3, infants were tested in a condition of more marked TP decrease, and a novelty syllabic segmentation effect was observed. Therefore, the present study first establishes early syllabic segmentation in French-learning infants, bringing support from a syllable-based language to the proposal that rhythmic units are used at the onset of segmentation abilities. Second, it confirms that French-learning infants are sensitive to TP cues. Third, it demonstrates that they are sensitive to the relative weight of TP and rhythmic cues, explaining why effects of syllabic segmentation are not observed in context of high TPs. These findings are discussed in relation to theories of word segmentation bootstrapping, and the larger debate about statistically- versus prosodically-based accounts of early language acquisition.

Younger versus older infants’ use of prosody-like boundaries to locate musical phrases

In spoken language, particularly of the infant-directed variety, clauses are marked with prosodic cues, such as final lengthening and pitch resets at boundaries (e.g., Soderstrom et al., 2008). Though prosody is specific to language, similar acoustic cues mark phrase boundaries in music, and infants are sensitive to the correlation of these cues at musical boundaries (Jusczyk and Krumhansl, 1993). In the present study, we ask whether younger (4-month-old) and older (16-month-old) infants can use prosody-like boundary cues to facilitate recognition of musical phrases. In a musical extension of Soderstrom et al. (2005), infants were familiarized with one of two brief melodies, then were tested using the head-turn preference procedure on their ability to recognize a phrase versus phrase-straddling excerpt from the familiarization melody when it is embedded in a new musical passage. Preliminary results suggest that younger infants show a familiarity preference for the test melody containing a phrase from the familiarized melody, while older infants do not discriminate between the test item types. This suggests that young infants use prosody-like cues to group acoustic stimuli in a domain-general way, whereas older infants may not.

Toddlers Activate Lexical Semantic Knowledge in the Absence of Visual Referents: Evidence from Auditory Priming.

Language learners rapidly acquire extensive semantic knowledge, but the development of this knowledge is difficult to study, in part because it is difficult to assess young children's lexical semantic representations. In our studies, we solved this problem by investigating lexical semantic knowledge in 24-month-olds using the Head-turn Preference Procedure. In Experiment 1, looking times to a repeating spoken word stimulus (e.g., kitty-kitty-kitty) were shorter for trials preceded by a semantically related word (e.g., dog-dog-dog) than trials preceded by an unrelated word (e.g., juice-juice-juice). Experiment 2 yielded similar results using a method in which pairs of words were presented on the same trial. The studies provide evidence that young children activate of lexical semantic knowledge, and critically, that they do so in the absence of visual referents or sentence contexts. Auditory lexical priming is a promising technique for studying the development and structure of semantic knowledge in young children.

Experimental methods in studying child language acquisition.

This article reviews the some of the most widely used methods used for studying children's language acquisition including (1) spontaneous/naturalistic, diary, parental report data, (2) production methods (elicited production, repetition/elicited imitation, syntactic priming/weird word order), (3) comprehension methods (act-out, pointing, intermodal preferential looking, looking while listening, conditioned head turn preference procedure, functional neuroimaging) and (4) judgment methods (grammaticality/acceptability judgments, yes-no/truth-value judgments). The review outlines the types of studies and age-groups to which each method is most suited, as well as the advantage and disadvantages of each. We conclude by summarising the particular methodological considerations that apply to each paradigm and to experimental design more generally. These include (1) choosing an age-appropriate task that makes communicative sense (2) motivating children to co-operate, (3) choosing a between-/within-subjects design, (4) the use of novel items (e.g., novel verbs), (5) fillers, (6) blocked, counterbalanced and random presentation, (7) the appropriate number of trials and participants, (8) drop-out rates (9) the importance of control conditions, (10) choosing a sensitive dependent measure (11) classification of responses, and (12) using an appropriate statistical test. WIREs Cogn Sci 2013, 4:149-168. doi: 10.1002/wcs.1215 For further resources related to this article, please visit the WIREs website. The authors declare no conflict of interest.

A computational model to investigate assumptions in the headturn preference procedure.

In this paper we use a computational model to investigate four assumptions that are tacitly present in interpreting the results of studies on infants' speech processing abilities using the Headturn Preference Procedure (HPP): (1) behavioral differences originate in different processing; (2) processing involves some form of recognition; (3) words are segmented from connected speech; and (4) differences between infants should not affect overall results. In addition, we investigate the impact of two potentially important aspects in the design and execution of the experiments: (a) the specific voices used in the two parts on HPP experiments (familiarization and test) and (b) the experimenter's criterion for what is a sufficient headturn angle. The model is designed to be maximize cognitive plausibility. It takes real speech as input, and it contains a module that converts the output of internal speech processing and recognition into headturns that can yield real-time listening preference measurements. Internal processing is based on distributed episodic representations in combination with a matching procedure based on the assumptions that complex episodes can be decomposed as positive weighted sums of simpler constituents. Model simulations show that the first assumptions hold under two different definitions of recognition. However, explicit segmentation is not necessary to simulate the behaviors observed in infant studies. Differences in attention span between infants can affect the outcomes of an experiment. The same holds for the experimenter's decision criterion. The speakers used in experiments affect outcomes in complex ways that require further investigation. The paper ends with recommendations for future studies using the HPP.

The Development of Word Stress Processing in French and Spanish Infants

This study focuses on the development of lexical stress perception during the first year of life. Previous research shows that cross-linguistic differences in word stress organization translate into differences in word stress processing from a very early age: At 9 months, Spanish-learning infants, learning a language with variable word stress, can discriminate between segmentally varied nonsense words with initial stress (e.g., níla, túli) and final stress (e.g., lutá, pukí) in a headturn preference procedure. However, French infants, who learn a language with fixed word stress, can only distinguish between initial and final stress when no segmental variability is involved (Skoruppa et al., 2009). The present study investigates the emergence of this cross-linguistic difference. We show that at six months, neither Spanish nor French infants encode stress patterns in the presence of segmental variability (Experiment 1), while both groups succeed in the absence of segmental variability (Experiment 2). Hence, only Spanish infants, who learn a variable stress language, get better at tracking stress patterns in segmentally varied words between the ages of 6 and 9 months. In contrast, all infants seem to be able to discriminate basic stress patterns in the absence of segmental variability during the first nine months of life, regardless of the status of stress in their native language.

Effects of Prior Phonotactic Knowledge on Infant Word Segmentation: The Case of Nonadjacent Dependencies

In this study, the authors explored whether French-learning infants use nonadjacent phonotactic regularities in their native language, which they learn between the ages of 7 and 10 months, to segment words from fluent speech. Two groups of 20 French-learning infants were tested using the head-turn preference procedure at 10 and 13 months of age. In Experiment 1, infants were familiarized with 2 passages: 1 containing a target word with a frequent nonadjacent phonotactic structure and the other containing a target word with an infrequent nonadjacent phonotactic structure in French. During the test phase, infants were presented with 4 word lists: 2 containing the target words presented during familiarization and 2 other control words with the same phonotactic structure. In Experiment 2, the authors retested infants' ability to segment words with the infrequent phonotactic structure. Ten- and 13-month-olds were able to segment words with the frequent phonotactic structure, but it is only by 13 months, and only under the circumstances of Experiment 2, that infants could segment words with the infrequent phonotactic structure. These results provide new evidence showing that infant word segmentation is influenced by prior nonadjacent phonotactic knowledge.

When do infants begin recognizing familiar words in sentences?

Previous studies have shown that by 11 but not by 10 months infants recognize words that have become familiar from everyday life independently of the experimental setting. This study explored the ability of 10-, 11-, and 12-month-old infants to recognize familiar words in sentential context, without experimental training. The headturn preference procedure was used to contrast passages containing words likely to be familiar to the infants with passages containing words unlikely to have been previously heard. Two stimulus words were inserted near the beginning and end of each of a set of simple sentence frames. The ability to recognize the familiar words within sentences emerged only at 12 months of age. The contrast between segmentation abilities as they emerge as a result of everyday exposure to language, as assessed here, and those abilities as measured in studies in which words are experimentally trained is discussed in terms of memory-based mechanisms.