Publications

Abstract

While infants' sensitivity to visual speech cues and the benefit of these cues have been well-established by behavioural studies, there is little evidence on the effect of visual speech cues on infants' neural processing of continuous auditory speech. In this study, we investigated whether visual speech cues, such as the movements of the lips, jaw, and larynx, facilitate infants' neural speech tracking. Ten-month-old Dutch-learning infants watched videos of a speaker reciting passages in infant-directed speech while electroencephalography (EEG) was recorded. In the videos, either the full face of the speaker was displayed or the speaker's mouth and jaw were masked with a block, obstructing the visual speech cues. To assess neural tracking, speech-brain coherence (SBC) was calculated, focusing particularly on the stress and syllabic rates (1–1.75 and 2.5–3.5 Hz respectively in our stimuli). First, overall, SBC was compared to surrogate data, and then, differences in SBC in the two conditions were tested at the frequencies of interest. Our results indicated that infants show significant tracking at both stress and syllabic rates. However, no differences were identified between the two conditions, meaning that infants' neural tracking was not modulated further by the presence of visual speech cues. Furthermore, we demonstrated that infants' neural tracking of low-frequency information is related to their subsequent vocabulary development at 18 months. Overall, this study provides evidence that infants' neural tracking of speech is not necessarily impaired when visual speech cues are not fully visible and that neural tracking may be a potential mechanism in successful language acquisition.

Abstract

The environment in which infants learn language is multimodal and rich with social cues. Yet, the effects of such cues, such as eye contact, on early speech perception have not been closely examined. This study assessed the role of ostensive speech, signalled through the speaker's eye gaze direction, on infants’ word segmentation abilities. A familiarisation-then-test paradigm was used while electroencephalography (EEG) was recorded. Ten-month-old Dutch-learning infants were familiarised with audio-visual stories in which a speaker recited four sentences with one repeated target word. The speaker addressed them either with direct or with averted gaze while speaking. In the test phase following each story, infants heard familiar and novel words presented via audio-only. Infants’ familiarity with the words was assessed using event-related potentials (ERPs). As predicted, infants showed a negative-going ERP familiarity effect to the isolated familiarised words relative to the novel words over the left-frontal region of interest during the test phase. While the word familiarity effect did not differ as a function of the speaker's gaze over the left-frontal region of interest, there was also a (not predicted) positive-going early ERP familiarity effect over right fronto-central and central electrodes in the direct gaze condition only. This study provides electrophysiological evidence that infants can segment words from audio-visual speech, regardless of the ostensiveness of the speaker's communication. However, the speaker's gaze direction seems to influence the processing of familiar words.

Abstract

Children’s songs are a great source for linguistic learning. Here we explore whether children can acquire novel words in a second language by playing a game featuring children’s songs in a playhouse. The playhouse is designed by the Noplica foundation (www.noplica.nl) to advance language learning through unsupervised play. We present data from three experiments that serve to scientifically proof the functionality of one game of the playhouse: the Energy Center. For this game, children move three hand-bikes mounted on a panel within the playhouse. Once the children cycle, a song starts playing that is accompanied by musical instruments. In our experiments, children executed a picture-selection task to evaluate whether they acquired new vocabulary from the songs presented during the game. Two of our experiments were run in the field, one at a Dutch and one at an Indian pre-school. The third experiment features data from a more controlled laboratory setting. Our results partly confirm that the Energy Center is a successful means to support vocabulary acquisition in a second language. More research with larger sample sizes and longer access to the Energy Center is needed to evaluate the overall functionality of the game. Based on informal observations at our test sites, however, we are certain that children do pick up linguistic content from the songs during play, as many of the children repeat words and phrases from the songs they heard. We will pick up upon these promising observations during future studies.

Abstract

Infants exploit acoustic boundaries to perceptually organize phrases in speech. This prosodic parsing ability is well‐attested and is a cornerstone to the development of speech perception and grammar. However, infants also receive linguistic input in child songs. This study provides evidence that infants parse songs into meaningful phrasal units and replicates previous research for speech. Six‐month‐old Dutch infants (n = 80) were tested in the song or speech modality in the head‐turn preference procedure. First, infants were familiarized to two versions of the same word sequence: One version represented a well‐formed unit, and the other contained a phrase boundary halfway through. At test, infants were presented two passages, each containing one version of the familiarized sequence. The results for speech replicated the previously observed preference for the passage containing the well‐formed sequence, but only in a more fine‐grained analysis. The preference for well‐formed phrases was also observed in the song modality, indicating that infants recognize phrase structure in song. There were acoustic differences between stimuli of the current and previous studies, suggesting that infants are flexible in their processing of boundary cues while also providing a possible explanation for differences in effect sizes.

Abstract

Children’s songs are omnipresent and highly attractive stimuli in infants’ input. Previous work suggests that infants process linguistic–phonetic information from simplified sung melodies. The present study investigated whether infants learn words from ecologically valid children’s songs. Testing 40 Dutch-learning 10-month-olds in a familiarization-then-test electroencephalography (EEG) paradigm, this study asked whether infants can segment repeated target words embedded in songs during familiarization and subsequently recognize those words in continuous speech in the test phase. To replicate previous speech work and compare segmentation across modalities, infants participated in both song and speech sessions. Results showed a positive event-related potential (ERP) familiarity effect to the final compared to the first target occurrences during both song and speech familiarization. No evidence was found for word recognition in the test phase following either song or speech. Comparisons across the stimuli of the present and a comparable previous study suggested that acoustic prominence and speech rate may have contributed to the polarity of the ERP familiarity effect and its absence in the test phase. Overall, the present study provides evidence that 10-month-old infants can segment words embedded in songs, and it raises questions about the acoustic and other factors that enable or hinder infant word segmentation from songs and speech.

Abstract

Native speakers of Dutch do not always adhere to prescriptive grammar rules in their daily speech. These grammatical norm violations can elicit emotional reactions in language purists, mostly high-educated people, who claim that for them these constructions are truly ungrammatical. However, linguists generally assume that grammatical norm violations are in fact truly grammatical, especially when they occur frequently in a language. In an fMRI study we investigated the processing of grammatical norm violations in the brains of language purists, and compared them with truly grammatical and truly ungrammatical sentences. Grammatical norm violations were found to be unique in that their processing resembled not only the processing of truly grammatical sentences (in left medial Superior Frontal Gyrus and Angular Gyrus), but also that of truly ungrammatical sentences (in Inferior Frontal Gyrus), despite what theories of grammar would usually lead us to believe