German-learning Infants Research Articles

Toddlers and Adults Link Nouns to Typical Space, but What do Infants do?

ABSTRACT When adults hear a noun with an implicit up location, like “moon”, they typically respond faster with an up compared to a down response. Conversely, for nouns with an implicit down location, like “stone”, they respond faster with a down response. We test when respective language-space associations develop. German-learning infants (11–14 months), toddlers (2–4 years) and adults participated in an eye-tracking experiment. Participants first heard a noun implying an up or down location. We selected nouns that are likely to be known even by the infants. Following the spoken word, a target stimulus appeared either at the upper or lower screen part. In half of the trials the target appeared at the noun’s implicit position. In the other half of the trials the target appeared in the opposite position. Participants’ time to fixate the target (our preregistered measure) was not influenced by the previously heard nouns. We discuss methodological challenges of infant research that might have compromised the power needed for this preregistered analysis. However, our exploratory measure – participants’ fixations while listening to the implicit spatial words – revealed language-space association in adults and toddlers (but not in infants). Adults and toddlers fixated the upper part of the screen more than the lower part while listening to an “up word” and, conversely, the lower part more while listening to a “down word”. Thereby, our results provide evidence that children link nouns to typical space at least from the age of two.

German infants’ discrimination of the English /æ/-/ɛ/ contrast: Evidence from a cross-sectional and a longitudinal study

Young infants can discriminate many non-native sounds, but the discrimination ability is thought to decrease within the first year of life due to perceptual attunement. However, most studies tested infants’ perception cross-sectionally, without examining within-group change. To this end, the current study tested German infants’ discrimination of the English /æ/-/ɛ/ contrast both cross-sectionally and longitudinally using the visual habituation technique. In Experiment 1, 96 German-learning infants were tested cross-sectionally at 5–6, 8–9 and 12–13 months. Linear mixed-effects models revealed that while the 5–6-month-olds did not discriminate the contrast, the 8–9- and 12–13-month-olds showed signs of discrimination only when they were habituated with /ɛ/, in line with previous findings suggesting that changes from central to peripheral vowels in the F1/F2 vowel space are more noticeable than in the reverse direction. Moreover, the 8–9-month-olds showed a novelty preference, while the 12–13-month-olds showed a familiarity preference. In Experiment 2, the infants tested at 5–6 months in Experiment 1 were tested again at 8–9 and 12–13 months. Fifteen infants completed the three experiments. Here, only the 12–13-month-olds discriminated the contrast by showing a novelty preference but only when habituated with /æ/. Overall, both experiments showed gradual development of discrimination ability across the first year, which challenges the assumptions of perceptual attunement. We propose that the perceptual sensitivity for a non-native vocalic contrast can improve during development. The change in perceptual asymmetry tells us that the direction of asymmetry is not universal and can be altered by linguistic experience. The change from novelty to familiarity preference may be due to the emerging preference for the more native-like vowel as well as the effect of repeating experiments with the same infants. In sum, our cross-sectional and longitudinal results overlap broadly, but the potential effect of repeating experiments must be considered when interpreting longitudinal studies.

Prosody outweighs statistics in 6-month-old German-learning infants' speech segmentation.

It is well established that infants use various cues to find words within fluent speech from about 7 to 8months of age. Research suggests that two main mechanisms support infants' speech segmentation: prosodic cues like the word stress patterns, and distributional cues like transitional probabilities (TPs). We tested 6-month-old German-learning infants' use of prosodic and statistical cues for speech segmentation in three experiments. In Experiment 1, infants were familiarized with an artificial language string where TPs signaled either word boundaries or iambic words-a stress pattern that is disfavored in German. Experiment 2 was a control and only the test phase was presented. In Experiment 3, prosodic cues were absent in the string and only TPs signaled word boundaries. All experiments included the same conditions at test: disyllabic words with high TPs in the string, words with low TPs and words with non-co-occurring syllables. Results showed that infants relied more strongly on prosodic cues than on TPs for word segmentation. Notably, no segmentation evidence emerged when prosodic cues were absent in the string. This finding underlines early impacts of language-specific structural properties on segmentation mechanisms.

Neural correlates of lexical-tone and vowel-quality processing in 6- and 9-month-old German-learning infants and adults.

We examined the neurophysiological underpinnings of lexical-tone and vowel-quality perception in learners of a non-tonal language. We tested 25 6- and 25 9-month-old German-learning infants, as well as 24 German adults and expected developmental differences for the two linguistic properties, as they are both carried by vowels, but have a different status in German. In adults, both lexical-tone and vowel-quality contrasts elicited mismatch negativities, with a stronger response to the vowel-quality contrast. Six-month-olds showed positive mismatch responses for lexical-tone and vowel-quality contrasts, with an emerging negative mismatch response for vowel-quality only. The negative mismatch responses became more pronounced for the vowel-quality contrast at 9 months, while the lexical-tone contrast elicited mainly positive mismatch responses. Our data reveal differential developmental changes in the processing of vowel properties that differ in their lexical relevance in the ambient language.

Infants' sensitivity to phonotactic regularities related to perceptually low-salient fricatives: a cross-linguistic study.

Infants' sensitivity to language-specific phonotactic regularities emerges between 6- and 9- months of age, and this sensitivity has been shown to impact other early processes such as wordform segmentation and word learning. However, the acquisition of phonotactic regularities involving perceptually low-salient phonemes (i.e., phoneme contrasts that are hard to discriminate at an early age), has rarely been studied and prior results show mixed findings. Here, we aimed to further assess infants' acquisition of such regularities, by focusing on the low-salient contrast of /s/- and /ʃ/-initial consonant clusters. Using the headturn preference procedure, we assessed whether French- and German-learning 9-month-old infants are sensitive to language-specific regularities varying in frequency within and between the two languages (i.e., /st/ and /sp/ frequent in French, but infrequent in German, /ʃt/ and /ʃp/ frequent in German, but infrequent in French). French-learning infants preferred the frequent over the infrequent phonotactic regularities, but the results for the German-learning infants were less clear. These results suggest crosslinguistic acquisition patterns, although an exploratory direct comparison of the French- and German-learning groups was inconclusive, possibly linked to low statistical power to detect such differences. Nevertheless, our findings suggest that infants' early phonotactic sensitivities extend to regularities involving perceptually low-salient phoneme contrasts at 9 months, and highlight the importance of conducting cross-linguistic research on such language-specific processes.

Music and language in the crib: Early cross-domain effects of experience on categorical perception of prominence in spoken language.

Rhythm perception helps young infants find structure in both speech and music. However, it remains unknown whether categorical perception of suprasegmental linguistic rhythm signaled by a co-variation of multiple acoustic cues can be modulated by prior between- (music) and within-domain (language) experience. Here we tested 6-month-old German-learning infants' ability to have a categorical perception of lexical stress, a linguistic prominence signaled through the co-variation of pitch, intensity, and duration. By measuring infants' pupil size, we find that infants as a group fail to perceive co-variation of these acoustic cues as categorical. However, at an individual level, infants with above-average exposure to music and language at home succeeded. Our results suggest that early exposure to music and infant-directed language can boost the categorical perception of prominence. RESEARCH HIGHLIGHTS: 6-month-old German-learning infants' ability to perceive lexical stress prominence categorically depends on exposure to music and language at home. Infants with high exposure to music show categorical perception. Infants with high exposure to infant-directed language show categorical perception. Co-influence of high exposure to music and infant-directed language may be especially beneficial for categorical perception. Early exposure to predictable rhythms boosts categorical perception of prominence.

Maturation of consonant perception, but not vowel perception, predicts lexical skills at 12 months.

Consonants and vowels differentially contribute to lexical acquisition. From 8months on, infants' preferential reliance on consonants has been shown to predict their lexical outcome. Here, the predictive value of German-learning infants' (n=58, 29 girls, 29 boys) trajectories of consonant and vowel perception, indicated by the electrophysiological mismatch response, across 2, 6, and 10months for later lexical acquisition was studied. The consonant-perception trajectory from 2 to 6months (β=-2.95) and 6 to 10months (β=-.91), but not the vowel-perception trajectory, significantly predicted receptive vocabulary at 12 months. These results reveal an earlier predictive value of consonant perception for word learning than previously found, and a particular role of the longitudinal maturation of this skill in lexical acquisition.

Pupillary entrainment reveals individual differences in cue weighting in 9-month-old German-learning infants

Young infants can segment continuous speech with statistical as well as prosodic cues. Understanding how these cues interact can be informative about how infants solve the segmentation problem. Here we investigate how German-speaking adults and 9-month-old German-learning infants weigh statistical and prosodic cues when segmenting continuous speech. We measured participants' pupil size while they were familiarized with a continuous speech stream where prosodic cues were pitted off against transitional probabilities. Adult participants' changes in pupil size synchronized with the occurrence of prosodic words during the familiarization and the temporal alignment of these pupillary changes was predictive of adult participants' performance at test. Further, 9-month-olds as a group failed to consistently segment the familiarization stream with prosodic or statistical cues. However, the variability in temporal alignment of the pupillary changes at word frequency showed that prosodic and statistical cues compete for dominance when segmenting continuous speech. A follow-up language development questionnaire at 40 months of age suggested that infants who entrained to prosodic words performed better on a vocabulary task and those infants who relied more on statistical cues performed better on grammatical tasks. Together these results suggest that statistics and prosody may serve different roles in speech segmentation in infancy.

No Evidence of Robust Noun-Referent Associations in German-Learning 6- to 14-Month-Olds.

Work with the looking-while-listening (LWL-) paradigm suggested that 6-month-old English-learning infants associated several labels for common nouns with pictures of their referents: While one distractor picture was present, infants systematically fixated the named target picture. However, recent work revealed constraints of infants' noun comprehension. The age at which these abilities can be obtained appears to relate to the infants' familiarity with the talker, the target language, and word frequency differences in target-distractor pairs. Here, we present further data to this newly established field of research. We tested 42 monolingual German-learning infants aged 6–14 months by means of the LWL-paradigm. Infants saw two pictures side-by-side on a screen, whilst an unfamiliar male talker named one of both. Overall, infants did not fixate the target picture more than the distractor picture. In line with previous results, infants' performance on the task was higher when target and distractor differed within their word frequency—as operationalized by the parental rating of word exposure. Together, our results add further evidence for constraints on early word learning. They point to cross-linguistic differences in early word learning and strengthen the view that infants might use extra-linguistic cues within the stimulus pairing, such as frequency imbalance, to disambiguate between two potential referents.

Only the right noise? Effects of phonetic and visual input variability on 14-month-olds' minimal pair word learning.

Seminal work by Werker and colleagues (Stager & Werker [1997] Nature, 388, 381-382) has found that 14-month-old infants do not show evidence for learning minimal pairs in the habituation-switch paradigm. However, when multiple speakers produce the minimal pair in acoustically variable ways, infants' performance improves in comparison to a single speaker condition (Rost & McMurray [2009] Developmental Science, 12, 339-349). The current study further extends these results and assesses how different kinds of input variability affect 14-month-olds' minimal pair learning in the habituation-switch paradigm testing German learning infants. The first two experiments investigated word learning when the labels were spoken by a single speaker versus when the labels were spoken by multiple speakers. In the third experiment we studied whether non-acoustic variability, implemented by visual variability of the objects presented together with the labels, would also affect minimal pair learning. We found enhanced learning in the multiple speakers compared to the single speaker condition, confirming previous findings with English-learning infants. In contrast, visual variability of the presented objects did not support learning. These findings both confirm and better delimit the beneficial role of speech-specific variability in minimal pair learning. Finally, we review different proposals on the mechanisms via which variability confers benefits to learning and outline what may be likely principles that underlie this benefit. We highlight among these the multiplicity of acoustic cues signalling phonemic contrasts and the presence of relations among these cues. It is in these relations where we trace part of the source for the apparent paradoxical benefit of variability in learning.

Language-specific prosodic acquisition: A comparison of phrase boundary perception by French- and German-learning infants

This study compares the development of prosodic processing in French- and German-learning infants. The emergence of language-specific perception of phrase boundaries was directly tested using the same stimuli across these two languages. French-learning (Experiment 1, 2) and German-learning 6- and 8-month-olds (Experiment 3) listened to the same French noun sequences with or without major prosodic boundaries ([Loulou et Manou][et Nina]; [Loulou et Manou et Nina], respectively). The boundaries were either naturally cued (Experiment 1), or cued exclusively by pitch and duration (Experiment 2, 3). French-learning 6- and 8-month-olds both perceived the natural boundary, but neither perceived the boundary when only two cues were present. In contrast, German-learning infants develop from not perceiving the two-cue boundary at 6 months to perceiving it at 8 months, just like German-learning 8-month-olds listening to German (Wellmann, Holzgrefe, Truckenbrodt, Wartenburger, & Höhle, 2012). In a control experiment (Experiment 4), we found little difference between German and French adult listeners, suggesting that later, French listeners catch up with German listeners. Taken together, these cross-linguistic differences in the perception of identical stimuli provide direct evidence for language-specific development of prosodic boundary perception.

Perceptual Reorganization of Lexical Tones: Effects of Age and Experimental Procedure.

Findings on the perceptual reorganization of lexical tones are mixed. Some studies report good tone discrimination abilities for all tested age groups, others report decreased or enhanced discrimination with increasing age, and still others report U-shaped developmental curves. Since prior studies have used a wide range of contrasts and experimental procedures, it is unclear how specific task requirements interact with discrimination abilities at different ages. In the present work, we tested German and Cantonese adults on their discrimination of Cantonese lexical tones, as well as German-learning infants between 6 and 18 months of age on their discrimination of two specific Cantonese tones using two different types of experimental procedures. The adult experiment showed that German native speakers can discriminate between lexical tones, but native Cantonese speakers show significantly better performance. The results from German-learning infants suggest that 6- and 18-month-olds discriminate tones, while 9-month-olds do not, supporting a U-shaped developmental curve. Furthermore, our results revealed an effect of methodology, with good discrimination performance at 6 months after habituation but not after familiarization. These results support three main conclusions. First, habituation can be a more sensitive procedure for measuring infants' discrimination than familiarization. Second, the previous finding of a U-shaped curve in the discrimination of lexical tones is further supported. Third, discrimination abilities at 18 months appear to reflect mature perceptual sensitivity to lexical tones, since German adults also discriminated the lexical tones with high accuracy.

Infants' Processing of Prosodic Cues: Electrophysiological Evidence for Boundary Perception beyond Pause Detection.

Infants as young as six months are sensitive to prosodic phrase boundaries marked by three acoustic cues: pitch change, final lengthening, and pause. Behavioral studies suggest that a language-specific weighting of these cues develops during the first year of life; recent work on German revealed that eight-month-olds, unlike six-month-olds, are capable of perceiving a prosodic boundary on the basis of pitch change and final lengthening only. The present study uses Event-Related Potentials (ERPs) to investigate the neuro-cognitive development of prosodic cue perception in German-learning infants. In adults' ERPs, prosodic boundary perception is clearly reflected by the so-called Closure Positive Shift (CPS). To date, there is mixed evidence on whether an infant CPS exists that signals early prosodic cue perception, or whether the CPS emerges only later-the latter implying that infantile brain responses to prosodic boundaries reflect acoustic, low-level pause detection. We presented six- and eight-month-olds with stimuli containing either no boundary cues, only a pitch cue, or a combination of both pitch change and final lengthening. For both age groups, responses to the former two conditions did not differ, while brain responses to prosodic boundaries cued by pitch change and final lengthening showed a positivity that we interpret as a CPS-like infant ERP component. This hints at an early sensitivity to prosodic boundaries that cannot exclusively be based on pause detection. Instead, infants' brain responses indicate an early ability to exploit subtle, relational prosodic cues in speech perception-presumably even earlier than could be concluded from previous behavioral results.

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.

Early Prosodic Acquisition in Bilingual Infants: The Case of the Perceptual Trochaic Bias.

Infants start learning the prosodic properties of their native language before 12 months, as shown by the emergence of a trochaic bias in English-learning infants between 6 and 9 months (Jusczyk et al., 1993), and in German-learning infants between 4 and 6 months (Höhle et al., 2009, 2014), while French-learning infants do not show a bias at 6 months (Höhle et al., 2009). This language-specific emergence of a trochaic bias is supported by the fact that English and German are languages with trochaic predominance in their lexicons, while French is a language with phrase-final lengthening but lacking lexical stress. We explored the emergence of a trochaic bias in bilingual French/German infants, to study whether the developmental trajectory would be similar to monolingual infants and whether amount of relative exposure to the two languages has an impact on the emergence of the bias. Accordingly, we replicated Höhle et al. (2009) with 24 bilingual 6-month-olds learning French and German simultaneously. All infants had been exposed to both languages for 30 to 70% of the time from birth. Using the Head Preference Procedure, infants were presented with two lists of stimuli, one made up of several occurrences of the pseudoword /GAba/ with word-initial stress (trochaic pattern), the second one made up of several occurrences of the pseudoword /gaBA/ with word-final stress (iambic pattern). The stimuli were recorded by a native German female speaker. Results revealed that these French/German bilingual 6-month-olds have a trochaic bias (as evidenced by a preference to listen to the trochaic pattern). Hence, their listening preference is comparable to that of monolingual German-learning 6-month-olds, but differs from that of monolingual French-learning 6-month-olds who did not show any preference (Höhle et al., 2009). Moreover, the size of the trochaic bias in the bilingual infants was not correlated with their amount of exposure to German. The present results thus establish that the development of a trochaic bias in simultaneous bilinguals is not delayed compared to monolingual German-learning infants (Höhle et al., 2009) and is rather independent of the amount of exposure to German relative to French.

Use of bound morphemes (noun particles) in word segmentation by Japanese-learning infants

Abstract Recent studies have shown that English-, French-, and German-learning infants begin to use determiners to segment adjacent nouns before their first birthday. The present research extended the investigation to a typologically different language, Japanese, focusing on infants’ use of a high-frequency particle ga, a subject-marker. In Japanese, a particle follows, rather than precedes, the noun, and is usually followed by a predicate verb; thus particles rarely occur at utterance edges. Furthermore, a particle is not a free morpheme (like a determiner) but a bound morpheme. Although particles are frequently omitted in colloquial speech, the frequency of their occurrence is comparable to that of high-frequency determiners in a previously studied language, French. The results demonstrated that Japanese-learning infants used particles for word segmentation not at 10 and 12 months but at 15 months, which is later than the age at which infants begin to use determiners in previously studied languages. The reason for this delay was discussed in light of the properties of Japanese particles.

The influence of infant-directed speech on 12-month-olds’ intersensory perception of fluent speech

The present study examined whether infant-directed (ID) speech facilitates intersensory matching of audio–visual fluent speech in 12-month-old infants. German-learning infants’ audio–visual matching ability of German and French fluent speech was assessed by using a variant of the intermodal matching procedure, with auditory and visual speech information presented sequentially. In Experiment 1, the sentences were spoken in an adult-directed (AD) manner. Results showed that 12-month-old infants did not exhibit a matching performance for the native, nor for the non-native language. However, Experiment 2 revealed that when ID speech stimuli were used, infants did perceive the relation between auditory and visual speech attributes, but only in response to their native language. Thus, the findings suggest that ID speech might have an influence on the intersensory perception of fluent speech and shed further light on multisensory perceptual narrowing.

Cross-modal matching of audio-visual German and French fluent speech in infancy.

The present study examined when and how the ability to cross-modally match audio-visual fluent speech develops in 4.5-, 6- and 12-month-old German-learning infants. In Experiment 1, 4.5- and 6-month-old infants’ audio-visual matching ability of native (German) and non-native (French) fluent speech was assessed by presenting auditory and visual speech information sequentially, that is, in the absence of temporal synchrony cues. The results showed that 4.5-month-old infants were capable of matching native as well as non-native audio and visual speech stimuli, whereas 6-month-olds perceived the audio-visual correspondence of native language stimuli only. This suggests that intersensory matching narrows for fluent speech between 4.5 and 6 months of age. In Experiment 2, auditory and visual speech information was presented simultaneously, therefore, providing temporal synchrony cues. Here, 6-month-olds were found to match native as well as non-native speech indicating facilitation of temporal synchrony cues on the intersensory perception of non-native fluent speech. Intriguingly, despite the fact that audio and visual stimuli cohered temporally, 12-month-olds matched the non-native language only. Results were discussed with regard to multisensory perceptual narrowing during the first year of life.

Der frühe expressive Wortschatzumfang simultan mehrsprachig aufwachsender Kinder - ein diagnostisch relevantes Kriterium?

Bilingual young children's early expressive vocabulary size and its composition (as one domain of the language development) should be examined to find out whether children with a risk for delayed language development may be identified in this way. 30 bilingual kindergarten infants from Berlin (with simultaneous language acquisition; second language German) and 30 monolingual German infants from the greater areas of Stuttgart and Heidelberg were pair matched (mean chronological age 22.5 [SD 3.1] months; min 16; max 26). The German expressive vocabulary checklist Elternfragebogen zur Wort-schatzentwicklung im frühen Kindesalter (ELAN; Bockmann & Kiese-Himmel, 2006) was filled out by all parents. In addition, parents of bilingual infants completed the adaption of the German vocabulary checklist Sprachbeurteilung durch Eltern (SBE-2-KT; v. Suchodoletz & Sachse, 2008) for the second mother tongue. The monolinguals' word sum in the ELAN (145.7; SD 75.8) differed significantly (p=0.001) from the bilinguals' word sum (78.3; SD 78.9 words). In contrast, bilinguals did not significantly differ in their overall expressive vocabulary size (ELAN+SBE-2-KT: 101.2; SD 77.0 words) from their monolingual counterparts (ELAN). Because bilinguals had a similar sized overall early vocabulary (both languages) like monolingual German-learning infants, the diagnostic criterion to identify late talkers with 24 months of age (less than 50 German words and no word combinations) should not be applied to bilingually infants with simultaneously double language acquisition.

The naïve language expert: introduction to the research topic

The naïve language expert: introduction to the research topic