Language and ethnobiological skills decline precipitously in Papua New Guinea, the world's most linguistically diverse nation.

Papua New Guinea is home to >10% of the world's languages and rich and varied biocultural knowledge, but the future of this diversity remains unclear. We measured language skills of 6,190 students speaking 392 languages (5.5% of the global total) and modeled their future trends using individual-level variables characterizing family language use, socioeconomic conditions, students' skills, and language traits. This approach showed that only 58% of the students, compared to 91% of their parents, were fluent in indigenous languages, while the trends in key drivers of language skills (language use at home, proportion of mixed-language families, urbanization, students' traditional skills) predicted accelerating decline of fluency to an estimated 26% in the next generation of students. Ethnobiological knowledge declined in close parallel with language skills. Varied medicinal plant uses known to the students speaking indigenous languages are replaced by a few, mostly nonnative species for the students speaking English or Tok Pisin, the national lingua franca. Most (88%) students want to teach indigenous language to their children. While crucial for keeping languages alive, this intention faces powerful external pressures as key factors (education, cash economy, road networks, and urbanization) associated with language attrition are valued in contemporary society.

Cross-clause planning in Nungon (Papua New Guinea): Eye-tracking evidence.

Hundreds of languages worldwide use a sentence structure known as the "clause chain," in which 20 or more clauses can be stacked to form a sentence. The Papuan language Nungon is among a subset of clause chaining languages that require "switch-reference" suffixes on nonfinal verbs in chains. These suffixes announce whether the subject of each upcoming clause will differ from the subject of the previous clause. We examine two major issues in psycholinguistics: predictive processing in comprehension, and advance planning in production. Whereas previous work on other languages has demonstrated that sentence planning can be incremental, switch-reference marking would seem to prohibit strictly incremental planning, as it requires speakers to plan the next clause before they can finish producing the current one. This suggests an intriguing possibility: planning strategies may be fundamentally different in Nungon. We used a mobile eye-tracker and solar-powered laptops in a remote village in Papua, New Guinea, to track Nungon speakers' gaze in two experiments: comprehension and production. Curiously, during comprehension, fixation data failed to find evidence that switch-reference marking is used for predictive processing. However, during production, we found evidence for advance planning of switch-reference markers, and, by extension, the subjects they presage. We propose that this degree of advance syntactic planning pushes the boundaries of what is known about sentence planning, drawing on data from a novel morpheme type in an understudied language.

An acoustic phonetic description of Nungon vowels.

This study is a comprehensive acoustic description and analysis of the six vowels /i e a u o ɔ/ in the Towet dialect of the Papuan language Nungon ⟨yuw⟩ of northeastern Papua New Guinea. Vowel tokens were extracted from a corpus of audio speech recordings created for general language documentation and grammatical description. To assess the phonetic correlates of a claimed phonological vowel length distinction, vowel duration was measured. Multi-point acoustic analyses enabled investigation of mean vowel F1, F2, and F3; vowel trajectories, and coarticulation effects. The three Nungon back vowels were of particular interest, as they contribute to an asymmetrical, back vowel-heavy array, and /o/ had previously been described as having an especially low F2. The authors found that duration of phonologically long and short vowels differed significantly. Mean vowel formant measurements confirmed that the six phonological vowels form six distinct acoustic groupings; trajectories show slightly more formant movement in some vowels than was previously known. Adjacent nasal consonants exerted significant effects on vowel formant measurements. The authors show that an uncontrolled, general documentation corpus for an under-described language can be mined for acoustic analysis, but coarticulation effects should be taken into account.

The root nominal stage: a case study of early Nungon verbs.

The 'root infinitive' phenomenon in child speech is known from major languages such as Dutch. In this case study, a child acquiring the Papuan language Nungon in a remote village setting in Papua New Guinea uses two different non-finite verb forms as predicates of main clauses ('root' contexts) between ages 2;3 and 3;3. The first root non-finite form is an apparent innovation of the child, unacceptable in adult-to-adult speech, which must be learned from a special auxiliary construction in child-directed speech. The second root non-finite form functions like attested adult main clause use of the same form. During the study period, the first root non-finite form increases sharply to function as a default verb form, then decreases to nil by 3;2. The second increases gradually to near-adult levels. Both forms are non-finite and have similar proportions in the input. Thus, factors other than finiteness and frequency must explain their distributions.

Early verb production in Nungon.

This brief research report presents a comparison of the early verb productions of four children acquiring the Papuan language Nungon as a first language. A previous case study examined only verb productions of the child TO; these are now compared with those from three other children, studied from ages 1;1-2;7 (non-dense corpus; one child, AB) and ages 2;4-2;7 (dense corpora; two children, MK and MF). Two of the most striking features of TO's early verb productions are shown to be outliers relative to the other three children: her 'root nominals' stage and her delayed near future tense production. Neither of these is transparently linked to patterns in her parents' child-directed speech. The other children also display differing strategies into language production. The dense corpus is beneficial for catching tokens of less-frequent inflections, but the frequent long recording sessions may be difficult for at least one child to tolerate.

Evidence for a universal association of auditory roughness with musical stability.

We provide evidence that the roughness of chords-a psychoacoustic property resulting from unresolved frequency components-is associated with perceived musical stability (operationalized as finishedness) in participants with differing levels and types of exposure to Western or Western-like music. Three groups of participants were tested in a remote cloud forest region of Papua New Guinea (PNG), and two groups in Sydney, Australia (musicians and non-musicians). Unlike prominent prior studies of consonance/dissonance across cultures, we framed the concept of consonance as stability rather than as pleasantness. We find a negative relationship between roughness and musical stability in every group including the PNG community with minimal experience of musical harmony. The effect of roughness is stronger for the Sydney participants, particularly musicians. We find an effect of harmonicity-a psychoacoustic property resulting from chords having a spectral structure resembling a single pitched tone (such as produced by human vowel sounds)-only in the Sydney musician group, which indicates this feature's effect is mediated via a culture-dependent mechanism. In sum, these results underline the importance of both universal and cultural mechanisms in music cognition, and they suggest powerful implications for understanding the origin of pitch structures in Western tonal music as well as on possibilities for new musical forms that align with humans' perceptual and cognitive biases. They also highlight the importance of how consonance/dissonance is operationalized and explained to participants-particularly those with minimal prior exposure to musical harmony.

Vowel acoustics of Nungon child-directed speech, adult dyadic conversation, and foreigner-directed monologues.

In many communities around the world, speech to infants (IDS) and small children (CDS) has increased mean pitch, increased pitch range, increased vowel duration, and vowel hyper-articulation when compared to speech directed to adults (ADS). Some of these IDS and CDS features are also attested in foreigner-directed speech (FDS), which has been studied for a smaller range of languages, generally major national languages, spoken by millions of people. We examined vowel acoustics in CDS, conversational ADS, and monologues directed to a foreigner (possible FDS, labeled MONO here) in the Towet dialect of the Papuan language Nungon, spoken by 300 people in a remote region in northeastern Papua New Guinea. Previous work established that Nungon CDS entails optional use of consonant alteration, special nursery vocabulary, and special morphosyntax. This study shows that Nungon CDS to children aged 2;2-3;10 lacks vowel hyper-articulation, but still displays other common prosodic traits of CDS styles around the world: increased mean pitch and pitch range. A developmental effect was also attested, in that speech to 2-year-olds contained vowels that were significantly longer than those in speech to 3-year-olds, which in turn had vowels of similar duration to those in Nungon ADS. We also found that Nungon FDS vowel triangles, measured from monologues primarily directed to a non-native speaker, were significantly larger than those of either CDS or conversational ADS, indicating vowel hyper-articulation. The Nungon pattern may align with the patterns of vowels in Norwegian IDS, CDS, and FDS, where hyper-articulation is found in FDS, but not CDS or IDS. The languages of the New Guinea area constitute 20% of the world's languages, but neither an acoustic comparison of vowels in CDS and ADS, nor an acoustic study of FDS, has previously been completed for any language of New Guinea. The function of an FDS style in a small, closed community like those of much of New Guinea may differ from that in larger societies, since there are very few non-native speakers of Nungon. Thus, this study uses monologues recorded with a foreign researcher as interlocutor to study Nungon FDS.

Emotional responses in Papua New Guinea show negligible evidence for a universal effect of major versus minor music.

Music is a vital part of most cultures and has a strong impact on emotions [1-5]. In Western cultures, emotive valence is strongly influenced by major and minor melodies and harmony (chords and their progressions) [6-13]. Yet, how pitch and harmony affect our emotions, and to what extent these effects are culturally mediated or universal, is hotly debated [2, 5, 14-20]. Here, we report an experiment conducted in a remote cloud forest region of Papua New Guinea, across several communities with similar traditional music but differing levels of exposure to Western-influenced tonal music. One hundred and seventy participants were presented with pairs of major and minor cadences (chord progressions) and melodies, and chose which of them made them happier. The experiment was repeated by 60 non-musicians and 19 musicians in Sydney, Australia. Bayesian analyses show that, for cadences, there is strong evidence that greater happiness was reported for major than minor in every community except one: the community with minimal exposure to Western-like music. For melodies, there is strong evidence that greater happiness was reported for those with higher mean pitch (major melodies) than those with lower mean pitch (minor melodies) in only one of the three PNG communities and in both Sydney groups. The results show that the emotive valence of major and minor is strongly associated with exposure to Western-influenced music and culture, although we cannot exclude the possibility of universality.

Singing the Individual: Name Tunes in Oyda and Yopno.

Music beats spoken language in identifying individuals uniquely in two disparate communities. In addition to their given names, which conform to the conventions of their languages, speakers of the Oyda (Omotic; SW Ethiopia) and Yopno (Finisterre-Huon; NE Papua New Guinea) languages have "name tunes," short 1-4 s melodies that can be sung or whistled to hail or to identify for other purposes. Linguistic given names, for both communities, are often non-unique: people may be named after ancestors or contemporaries, or bear given names common to multiple individuals. But for both communities, name tunes are generally non-compositional and unique to individuals. This means that each new generation is likely to bring thousands of new name tunes into existence. In both communities, name tunes are produced in a range of contexts, from quotidian summoning and mid-range communication, to ceremonial occasions. In their use of melodies to directly represent individual people, the Oyda and Yopno name tune systems differ from surrogate speech systems elsewhere that either: (a) mimic linguistic forms, or (b) use music to represent a relatively small set of messages. Also, unlike some other musical surrogate speech traditions, the Oyda and Yopno name tune systems continue to be used productively, despite societal changes that have led to declining use in some domains.

Word learning in the field: Adapting a laboratory-based task for testing in remote Papua New Guinea.

Adapting laboratory psycholinguistic methods to fieldwork contexts can be fraught with difficulties. However, successful implementation of such methods in the field enhances our ability to learn the true extent and limitations of human behavior. This paper reports two attempts to run word learning experiments with the small community of Nungon speakers in Towet village in the Saruwaged Mountains, Papua New Guinea. A first attempt involved running a cross-situational task in which word-object pairings were presented ambiguously in each trial, and an explicit word learning task in which pairings were presented explicitly, or unambiguously, in each trial. While this quickly garnered a respectable 34 participants over the course of a week, it yielded null results, with many participants appearing to show simple patterned responses at test. We interpreted the null result as possibly reflecting the unfamiliarity of both the task and the laptop-based presentation mode. In Experiment 2, we made several adjustments to the explicit word learning task in an attempt to provide clearer instructions, reduce cognitive load, and frame the study within a real-world context. During a second 11-day stay in the village, 34 participants completed this modified task and demonstrated clear evidence of word learning. With this success serving as a future guide for researchers, our experiences show that it may require multiple attempts, even by experienced fieldworkers familiar with the target community, to successfully adapt experiments to a field setting.

The Acquisition of Clause Chaining in Nungon.

The clause chain is an under-investigated complex sentence type, found in hundreds of languages. In a clause chain, as many as 20 or more 'medial' clauses with under-specified verbal predicates combine with a single 'final' clause with fully-specified verbal predicate. Clause chains are of interest for three main reasons: (a) the special syntactic relationship between clauses, which is neither textbook subordination nor coordination; (b) the potential extreme length of a single chain; and (c) switch-reference marking in clause chains of some languages could require speakers to plan at least one clause ahead as they speak. Research on child production of complex sentences has largely overlooked clause chains. Longitudinal data for three children aged 1;1 to 3;3 acquiring the Papuan language Nungon show that Nungon-speaking children begin producing clause chains around the age of 2;4, with a marked increase in rate of use around age 2;11. Chain length is limited to two clauses until age 3;1. Different-subject marking in medial clauses is used by all three children early, but is first attested in one-clause, 'root medial' contexts, rather than in chains. Bayesian statistical models confirm the strong tendency for children to use root medials in expressions of desires and commands. Children's production of three types of complex sentences-clause chains, subordinated final clauses, and coordinated final clauses-is shown to be subject to the same type of developmental constraint; but once development reaches an adequate level for increased complex sentence production, children acquiring Nungon produce many more clause chains than complex sentences involving subordinated or coordinated final clauses.

Beyond the Two-Clause Sentence: Acquisition of Clause Chaining in Six Languages.

Clause chains are a special type of complex sentence, found in hundreds of languages outside Western Europe, in which clauses are dependent but not embedded, and dozens of clauses can be combined into a single sentential unit. Unlike English complex sentences, clause chains' distribution is partially predictable in that they can, most fundamentally, be linked to a particular semantic context: description of temporally sequential events or actions. This and the morphological simplicity of verb forms in clause chains may combine to accelerate their acquisition by children, relative to complex sentences in other languages. No previous cross-linguistic studies of the acquisition of complex sentences have investigated clause chaining. In this paper, we report insights from a survey of the acquisition of clause chaining in six languages of diverse stocks with child speech databases spanning 1;1 to 10 years. Overall, children acquiring clause chaining languages begin to produce 2-clause chains between around 1;11 and 2;6. An initial stage in which chains are limited to just two clauses in length is followed by a stage in which longer chains of 3-5 clauses are also produced. Children acquiring languages in which adults produce both same-subject and different-subject clause chains produce a similar mix from early on; for some languages, this involves morphological "switch-reference" marking that anticipates the identity of the subject of an upcoming clause. This survey broadens our understanding of the acquisition of complex sentences by adding new data on the acquisition timing, semantics, and reference continuity of early clause chains.