Publications

Abstract

Children and adults are excellent word learners. Increasing evidence suggests that the neural mechanisms that allow us to learn words change with age. In a recent fMRI study from our group, several brain regions exhibited age-related differences when accessing newly learned words in a second language (L2; Takashima et al. Dev Cogn Neurosci 37, 2019). Namely, while the Teen group (aged 14–16 years) activated more left frontal and parietal regions, the Young group (aged 8–10 years) activated right frontal and parietal regions. In the current study we analyzed the structural connectivity data from the aforementioned study, examining the white matter connectivity of the regions that showed age-related functional activation differences. Age group differences in streamline density as well as correlations with L2 word learning success and their interaction were examined. The Teen group showed stronger connectivity than the Young group in the right arcuate fasciculus (AF). Furthermore, white matter connectivity and memory for L2 words across the two age groups correlated in the left AF and the right anterior thalamic radiation (ATR) such that higher connectivity in the left AF and lower connectivity in the right ATR was related to better memory for L2 words. Additionally, connectivity in the area of the right AF that exhibited age-related differences predicted word learning success. The finding that across the two age groups, stronger connectivity is related to better memory for words lends further support to the hypothesis that the prolonged maturation of the prefrontal cortex, here in the form of structural connectivity, plays an important role in the development of memory.

Abstract

Using language requires access to domain-specific linguistic representations, but also draws on domain-general cognitive skills. A key issue in current psycholinguistics is to situate linguistic processing in the network of human cognitive abilities. Here, we focused on spoken word recognition and used an individual differences approach to examine the links of scores in word recognition tasks with scores on tasks capturing effects of linguistic experience, general processing speed, working memory, and non-verbal reasoning. 281 young native speakers of Dutch completed an extensive test battery assessing these cognitive skills. We used psychometric network analysis to map out the direct links between the scores, that is, the unique variance between pairs of scores, controlling for variance shared with the other scores. The analysis revealed direct links between word recognition skills and processing speed. We discuss the implications of these results and the potential of psychometric network analysis for studying language processing and its embedding in the broader cognitive system.

Abstract

We introduce the Individual Differences in Language Skills (IDLaS-NL) web platform, which enables users to run studies on individual differences in Dutch language skills via the internet. IDLaS-NL consists of 35 behavioral tests, previously validated in participants aged between 18 and 30 years. The platform provides an intuitive graphical interface for users to select the tests they wish to include in their research, to divide these tests into different sessions and to determine their order. Moreover, for standardized administration the platform
provides an application (an emulated browser) wherein the tests are run. Results can be retrieved by mouse click in the graphical interface and are provided as CSV-file output via email. Similarly, the graphical interface enables researchers to modify and delete their study configurations. IDLaS-NL is intended for researchers, clinicians, educators and in general anyone conducting fundaental research into language and general cognitive skills; it is not intended for diagnostic purposes. All platform services are free of charge. Here, we provide a
description of its workings as well as instructions for using the platform. The IDLaS-NL platform can be accessed at www.mpi.nl/idlas-nl.

Abstract

In this study, we explored the relationship between developmental differences in gray matter structure and grammar learning ability in 159 Dutch-speaking individuals (8 to 25 yr). The data were collected as part of a recent large-scale functional MRI study (Menks WM, Ekerdt C, Lemhöfer K, Kidd E, Fernández G, McQueen JM, Janzen G. Developmental changes in brain activation during novel grammar learning in 8–25-year-olds. Dev Cogn Neurosci. 2024;66:101347. https://doi.org/10.1016/j.dcn.2024.101347) in which participants implicitly learned Icelandic morphosyntactic rules and performed a grammaticality judgment task in the scanner. Behaviorally, Menks et al. (2024) showed that grammaticality judgment task performance increased steadily from 8 to 15.4 yr, after which age had no further effect. We show in the current study that this age-related grammaticality judgment task performance was negatively related to cortical gray matter volume and cortical thickness in many clusters throughout the brain. Hippocampal volume was positively related to age-related grammaticality judgment task performance and L2 (English) vocabulary knowledge. Furthermore, we found that grammaticality judgment task performance, L2 grammar proficiency, and L2 vocabulary knowledge were positively related to gray matter maturation within parietal regions, overlapping with the functional MRI clusters that were reported previously in Menks et al. (2024) and which showed increased brain activation in relation to grammar learning. We propose that this overlap in functional and structural results indicates that brain maturation in parietal regions plays an important role in second language learning.

Abstract

While it is well established that grammar learning success varies with age, the cause of this developmental change is largely unknown. This study examined functional MRI activation across a broad developmental sample of 165 Dutch-speaking individuals (8-25 years) as they were implicitly learning a new grammatical system. This approach allowed us to assess the direct effects of age on grammar learning ability while exploring its neural correlates. In contrast to the alleged advantage of children language learners over adults, we found that adults outperformed children. Moreover, our behavioral data showed a sharp discontinuity in the relationship between age and grammar learning performance: there was a strong positive linear correlation between 8 and 15.4 years of age, after which age had no further effect. Neurally, our data indicate two important findings: (i) during grammar learning, adults and children activate similar brain regions, suggesting continuity in the neural networks that support initial grammar learning; and (ii) activation level is age-dependent, with children showing less activation than older participants. We suggest that these age-dependent processes may constrain developmental effects in grammar learning. The present study provides new insights into the neural basis of age-related differences in grammar learning in second language acquisition.

Abstract

Anecdotal evidence suggests that learning a new foreign language (FL) makes you forget previously learned FLs. To seek empirical evidence for this claim, we tested whether learning words in a previously unknown L3 hampers subsequent retrieval of their L2 translation equivalents. In two experiments, Dutch native speakers with knowledge of English (L2), but not Spanish (L3), first completed an English vocabulary test, based on which 46 participant-specific, known English words were chosen. Half of those were then learned in Spanish. Finally, participants’ memory for all 46 English words was probed again in a picture naming task. In Experiment 1, all tests took place within one session. In Experiment 2, we separated the English pre-test from Spanish learning by a day and manipulated the timing of the English post-test (immediately after learning vs. 1 day later). By separating the post-test from Spanish learning, we asked whether consolidation of the new Spanish words would increase their interference strength. We found significant main effects of interference in naming latencies and accuracy: Participants speeded up less and were less accurate to recall words in English for which they had learned Spanish translations, compared with words for which they had not. Consolidation time did not significantly affect these interference effects. Thus, learning a new language indeed comes at the cost of subsequent retrieval ability in other FLs. Such interference effects set in immediately after learning and do not need time to emerge, even when the other FL has been known for a long time.

Abstract

Different talkers speak differently, even within the same homogeneous group. These differences lead to acoustic variability in speech, causing challenges for correct perception of the intended message. Because previous descriptions of this acoustic variability have focused mostly on segments, talker variability in prosodic structures is not yet well documented. The present study therefore examined acoustic between-talker variability in word stress in Dutch. We recorded 40 native Dutch talkers from a participant sample with minimal dialectal variation and balanced gender, producing segmentally overlapping words (e.g., VOORnaam vs. voorNAAM; ‘first name’ vs. ‘respectable’, capitalization indicates lexical stress), and measured different acoustic cues to stress. Each individual participant’s acoustic measurements were analyzed using Linear Discriminant Analyses, which provide coefficients for each cue, reflecting the strength of each cue in a talker’s productions. On average, talkers primarily used mean F0, intensity, and duration. Moreover, each participant also employed a unique combination of cues, illustrating large prosodic variability between talkers. In fact, classes of cue-weighting tendencies emerged, differing in which cue was used as the main cue. These results offer the most comprehensive acoustic description, to date, of word stress in Dutch, and illustrate that large prosodic variability is present between individual talkers.

Abstract

Talkers vary in how they speak, resulting in acoustic variability in segments and prosody. Previous studies showed that listeners deal with segmental variability through perceptual learning and that these learning effects are stable over time. The present study examined whether this is also true for lexical stress variability. Listeners heard Dutch minimal pairs (e.g., VOORnaam vs. voorNAAM, ‘first name’ vs. ‘respectable’) spoken by two talkers. Half of the participants heard Talker 1 using only F0 to signal lexical stress and Talker 2 using only intensity. The other half heard the reverse. After a learning phase, participants were tested on words spoken by these talkers with conflicting stress cues (‘mixed items’; e.g., Talker 1 saying voornaam with F0 signaling initial stress and intensity signaling final stress). We found that, despite the conflicting cues, listeners perceived these items following what they had learned. For example, participants hearing the example mixed item described above who had learned that Talker 1 used F0 perceived initial stress (VOORnaam) but those who had learned that Talker 1 used intensity perceived final stress (voorNAAM). Crucially, this result was still present in a delayed test phase, showing that talker-specific learning about lexical stress is stable over time.

Abstract

The human brain deals with the infinite variability of speech through multiple mechanisms. Some of them rely solely on information in the speech input (i.e., signal-driven) whereas some rely on linguistic or real-world knowledge (i.e., knowledge-driven). Many signal-driven perceptual processes rely on the enhancement of acoustic differences between incoming speech sounds, producing contrastive adjustments. For instance, when an ambiguous voiceless fricative is preceded by a high fundamental frequency (f0) sentence, the fricative is perceived as having lower a spectral center of gravity (CoG). However, it is not clear whether knowledge of a talker’s typical f0 can lead to similar contrastive effects. This study investigated a possible talker f0 effect on fricative CoG perception. In the exposure phase, two groups of participants (N=16 each) heard the same talker at high or low f0 for 20 minutes. Later, in the test phase, participants rated fixed-f0 /?ɔk/ tokens as being /sɔk/ (i.e., high CoG) or /ʃɔk/ (i.e., low CoG), where /?/ represents a fricative from a 5-step /s/-/ʃ/ continuum. Surprisingly, the data revealed the opposite of our contrastive hypothesis, whereby hearing high f0 instead biased perception towards high CoG. Thus, we demonstrated that talker f0 information affects fricative CoG perception.

Abstract

Research with nonnative speech spans many different linguistic branches and topics. Most studies include one or a few well-known features of a particular accent. However, due to a lack of empirical studies, little is known about how common these features are among nonnative speakers or how uncommon they are among native speakers. Moreover, it remains to be seen whether findings from such studies generalize to lesser-known features. Here, we demonstrate a quantitative approach to study nonnative accent features using Dutch-accented English as an example. By analyzing the phonetic distances between transcriptions of speech samples, this approach can identify the features that best distinguish nonnative from native speech. In addition, we describe a method to test hypotheses about accent features by checking whether the prevalence of the features overall varies between native and nonnative speakers. Furthermore, we include English speakers from the United States and United Kingdom and native Dutch speakers from Belgium and The Netherlands to address the issue of regional accent variability in both the native and target language. We discuss the results concerning three observed features. Overall, the results provide empirical support for some well-known features of Dutch-accented English, but suggest that others may be infrequent among nonnatives or in fact frequent among natives. In addition, the findings reveal potentially new accent features, and factors that may modulate the expression of known features. Our study demonstrates a fruitful approach to study nonnative accent features that has the potential to expand our understanding of the phenomenon of accent.

Abstract

Acquiring a second language (L2) requires newly learned information to be integrated with existing knowledge. It has been proposed that several memory systems work together to enable this process of rapidly encoding new information and then slowly incorporating it with existing knowledge, such that it is consolidated and integrated into the language network without catastrophic interference. This chapter focuses on consolidation of L2 vocabulary. First, the complementary learning systems model is outlined, along with the model’s predictions regarding lexical consolidation. Next, word learning studies in first language (L1) that investigate the factors playing a role in consolidation, and the neural mechanisms underlying this, are reviewed. Using the L1 memory consolidation literature as background, the chapter then presents what is currently known about memory consolidation in L2 word learning. Finally, considering what is already known about L1 but not about L2, future research investigating memory consolidation in L2 neurocognition is proposed.

Abstract

During listening, brain activity tracks the rhythmic structures of speech signals. Here, we directly dissociated the contribution of neural envelope tracking in the processing of speech acoustic cues from that related to linguistic processing. We examined the neural changes associated with the comprehension of Noise-Vocoded (NV) speech using magnetoencephalography (MEG). Participants listened to NV sentences in a 3-phase training paradigm: (1) pre-training, where NV stimuli were barely comprehended, (2) training with exposure of the original clear version of speech stimulus, and (3) post-training, where the same stimuli gained intelligibility from the training phase. Using this paradigm, we tested if the neural responses of a speech signal was modulated by its intelligibility without any change in its acoustic structure. To test the influence of spectral degradation on neural envelope tracking independently of training, participants listened to two types of NV sentences (4-band and 2-band NV speech), but were only trained to understand 4-band NV speech. Significant changes in neural tracking were observed in the delta range in relation to the acoustic degradation of speech. However, we failed to find a direct effect of intelligibility on the neural tracking of speech envelope in both theta and delta ranges, in both auditory regions-of-interest and whole-brain sensor-space analyses. This suggests that acoustics greatly influence the neural tracking response to speech envelope, and that caution needs to be taken when choosing the control signals for speech-brain tracking analyses, considering that a slight change in acoustic parameters can have strong effects on the neural tracking response.

Abstract

Luthra, Peraza-Santiago, Beeson, Saltzman, Crinnion, and Magnuson (2021) present data from the lexically mediated compensation for coarticulation paradigm that they claim provides conclusive evidence in favor of top-down processing in speech perception. We argue here that this evidence does not support that conclusion. The findings are open to alternative explanations, and we give data in support of one of them (that there is an acoustic confound in the materials). Lexically mediated compensation for coarticulation thus remains elusive, while prior data from the paradigm instead challenge the idea that there is top-down processing in online speech recognition.

Abstract

While recent laboratory studies suggest that the use of competing languages is a driving force in foreign language (FL) attrition (i.e. forgetting), research on “real” attriters has failed to demonstrate
such a relationship. We addressed this issue in a large-scale longitudinal study, following German students throughout a study abroad in Spain and their first six months back in Germany. Monthly,
percentage-based frequency of use measures enabled a fine-grained description of language use.
L3 Spanish forgetting rates were indeed predicted by the quantity and quality of Spanish use, and
correlated negatively with L1 German and positively with L2 English letter fluency. Attrition rates
were furthermore influenced by prior Spanish proficiency, but not by motivation to maintain
Spanish or non-verbal long-term memory capacity. Overall, this study highlights the importance
of language use for FL retention and sheds light on the complex interplay between language
use and other determinants of attrition.

Abstract

Speech is perceived relative to the speech rate in the context. It is unclear, however, what information listeners use to compute speech rate. The present study examines whether listeners use the number of
syllables per unit time (i.e., syllable rate) as a measure of speech rate, as indexed by subsequent vowel perception. We ran two rate-normalization experiments in which participants heard duration-matched word lists that contained either monosyllabic
vs. bisyllabic words (Experiment 1), or monosyllabic vs. trisyllabic pseudowords (Experiment 2). The participants’ task was to categorize an /ɑ-aː/ continuum that followed the word lists. The monosyllabic condition was perceived as slower (i.e., fewer /aː/ responses) than the bisyllabic and
trisyllabic condition. However, no difference was observed between bisyllabic and trisyllabic contexts. Therefore, while syllable rate is used in perceiving speech rate, other factors, such as fast speech processes, mean F0, and intensity, must also influence rate normalization.

Abstract

When recognizing spoken words, listeners are confronted by variability in the speech signal caused by talker differences. Previous research has focused on segmental talker variability; less is known about how suprasegmental variability is handled. Here we investigated the use of perceptual learning to deal with between-talker differences in lexical stress. Two groups of participants heard Dutch minimal stress pairs (e.g., VOORnaam vs. voorNAAM, “first name” vs. “respectable”) spoken by two male talkers. Group 1 heard Talker 1 use only F0 to signal stress (intensity and duration values were ambiguous), while Talker 2 used only intensity (F0 and duration were ambiguous). Group 2 heard the reverse talker-cue mappings. After training, participants were tested on words from both talkers containing conflicting stress cues (“mixed items”; e.g., one spoken by Talker 1 with F0 signaling initial stress and intensity signaling final stress). We found that listeners used previously learned information about which talker used which cue to interpret the mixed items. For example, the mixed item described above tended to be interpreted as having initial stress by Group 1 but as having final stress by Group 2. This demonstrates that listeners learn how individual talkers signal stress and use that knowledge in spoken-word recognition.

Abstract

Over the course of a conversation, interlocutors sound more and more like each other in a process called convergence. However, the automaticity and grain size of convergence are not well established. This study therefore examined whether female native Dutch speakers converge to large yet sub-phonemic shifts in the F2 of the vowel /e/. Participants first performed a short reading task to establish baseline F2s for the vowel /e/, then shadowed 120 target words (alongside 360 fillers) which contained one instance of a manipulated vowel /e/ where the F2 had been shifted down to that of the vowel /ø/. Consistent exposure to large (sub-phonemic) downward shifts in F2 did not result in convergence. The results raise issues for theories which view convergence as a product of automatic integration between perception and production.

Abstract

It has been suggested that individual variation in vowel compactness of the native language (L1) and the distance between L1 vowels and vowels in the second language (L2) predict successful L2 vowel acquisition. Moreover, general articulatory skills have been proposed to account for variation in vowel compactness. In the present work, we conceptually replicate a previous study to test these hypotheses with a large sample size, a new language pair and a
new vowel pair. We find evidence that individual variation in L1 vowel compactness has opposing effects for two different vowels. We do not find evidence that individual variation in L1 compactness
is explained by general articulatory skills. We conclude that the results found previously might be specific to sub-groups of L2 learners and/or specific sub-sets of vowel pairs.

Abstract

The results of a study on perceptual learning are reported. Dutch subjects made lexical decisions on a list of words and nonwords. Embedded in the list were either [f]- or [s]-final words in which the final fricative had been replaced by an ambiguous sound, midway between [f] and [s]. One group of listeners heard ambiguous [f]- final Dutch words like [kara?] (based on karaf, carafe) and unambiguous [s]-final words (e.g., karkas, carcase). A second group heard the reverse (e.g., ambiguous [karka?] and unambiguous karaf). After this training phase, listeners labelled ambiguous fricatives on an [f]- [s] continuum. The subjects who had heard [?] in [f]- final words categorised these fricatives as [f] reliably more often than those who had heard [?] in [s]-final words. These results suggest that speech recognition is dynamic: the system adjusts to the constraints of each particular listening situation. The lexicon can provide this adjustment process with a training signal.

Abstract

We introduce the papers in this special issue by summarising the current major issues in spoken word recognition. We argue that a full understanding of the process of lexical access during speech comprehension will depend on resolving several key representational issues: what is the form of the representations used for lexical access; how is phonological information coded in the mental lexicon; and how is the morphological and semantic information about each word stored? We then discuss a number of distinct access processes: competition between lexical hypotheses; the computation of goodness-of-fit between the signal and stored lexical knowledge; segmentation of continuous speech; whether the lexicon influences prelexical processing through feedback; and the relationship of form-based processing to the processes responsible for deriving an interpretation of a complete utterance. We conclude that further progress may well be made by swapping ideas among the different sub-domains of the discipline.

Abstract

In two word-spotting experiments, Japanese listeners detected Japanese words faster in vowel contexts (e.g., agura, to sit cross-legged, in oagura) than in consonant contexts (e.g., tagura). In the same experiments, however, listeners spotted words in vowel contexts (e.g., saru, monkey, in sarua) no faster than in moraic nasal contexts (e.g., saruN). In a third word-spotting experiment, words like uni, sea urchin, followed contexts consisting of a consonant-consonant-vowel mora (e.g., gya) plus either a moraic nasal (gyaNuni), a vowel (gyaouni) or a consonant (gyabuni). Listeners spotted words as easily in the first as in the second context (where in each case the target words were aligned with mora boundaries), but found it almost impossible to spot words in the third (where there was a single consonant, such as the [b] in gyabuni, between the beginning of the word and the nearest preceding mora boundary). Three control experiments confirmed that these effects reflected the relative ease of segmentation of the words from their contexts.We argue that the listeners showed sensitivity to the viability of sound sequences as possible Japanese words in the way that they parsed the speech into words. Since single consonants are not possible Japanese words, the listeners avoided lexical parses including single consonants and thus had difficulty recognizing words in the consonant contexts. Even though moraic nasals are also impossible words, they were not difficult segmentation contexts because, as with the vowel contexts, the mora boundaries between the contexts and the target words signaled likely word boundaries. Moraic rhythm appears to provide Japanese listeners with important segmentation cues.

Abstract

Two word-spotting experiments are reported that examine whether the Possible-Word Constraint (PWC) is a language-specific or language-universal strategy for the segmentation of continuous speech. The PWC disfavours parses which leave an impossible residue between the end of a candidate word and any likely location of a word boundary, as cued in the speech signal. The experiments examined cases where the residue was either a CVC syllable with a schwa, or a CV syllable with a lax vowel. Although neither of these syllable contexts is a possible lexical word in English, word-spotting in both contexts was easier than in a context consisting of a single consonant. Two control lexical-decision experiments showed that the word-spotting results reflected the relative segmentation difficulty of the words in different contexts. The PWC appears to be language-universal rather than language-specific.

Abstract

Sentential context effects on the identification of the Dutch function words te (to) and de (the) were examined. In Experiment 1, listeners labeled words on a [tә]-[dә] continuum more often as te when the context was te biased (Ik probeer [?ә] schieten [I try to/the shoot]) than when it was de biased (Ik probeer [?ә] schoenen [I try to/the shoes]). The effect was weaker in slower responses. In Experiment 2, disambiguation began later, in the second word after [?ә]. There was a weak context effect only in the slower responses. In Experiments 3 and 4, disambiguation occurred on the word before [?ә]: There was no context effect when one set of sentences was used, but there was an effect (larger in the faster responses) when more sentences were used. Syntactic processing affects word identification only within a limited time frame. It appears to do so not by influencing lexical access processes through feedback but, instead, by biasing decision making.