Bart de Boer

Vrije Universiteit Brussel | VUB · Artificial Intelligence (ARTI)

We study the influence of phonological factors on morphological simplification using real-world data and computer simulations, suggesting a role for the context of building blocks in theories of protolanguage.

In this study, we investigate how humans use generalisation to learn verb forms for different grammatical persons and verbs and which role inflection classes play in this process. Inspired by recent advances in computational modelling of morphological processing (Elsner et al., 2019), we propose the task of unsupervised inflection class clustering:...

Affixes change over time, especially under social dynamics, such as adult language contact (Lupyan & Dale, 2010; Sinnemäki & Di Garbo, 2018) and dialect contact (Trudgill, 1986). To study the mechanisms behind affix change, we propose to simulate communication between speakers using agent-based computer simulations (Smith, 2014) in conjunction with...

This chapter reviews the history of the interaction between theories of evolution and phonology. It starts by looking at very early work on the origins of speech and then proceeds to present the (absence of) influence of theories of sound change on Darwin’s thinking about biological change, as well as Darwin’s and other late 19th-century ideas abou...

It has been suggested that social structure affects the degree of lexical variation in sign language emergence. Evidence from signing communities supports this, with smaller, more insular communities typically displaying a higher degree of lexical variation compared to larger, more dispersed and diverse communities. Though several factors have been...

We derive a weakly informative prior for a set of ordered resonance frequencies from Jaynes’ principle of maximum entropy. The prior facilitates model selection problems in which both the number and the values of the resonance frequencies are unknown. It encodes a weakly inductive bias, provides a reasonable density everywhere, is easily parametriz...

How music and speech evolved is a mystery. Several hypotheses on their origins, including one on their joint origins, have been put forward but rarely tested. Here we report and comment on the first experiment testing the hypothesis that speech and music bifurcated from a common system. We highlight strengths of the reported experiment, point out i...

In this paper, we propose an outline for linguistic research on language change, as observed in the languages of the world, using neural agent-based models of emergent communication. We describe how such models could be used to study morphological simplification, using a case study of language contact in Eastern Indonesia. A neural architecture is...

As evidence from sign languages is increasingly used to investigate the process of language emergence and evolution, it is important to understand the conditions that allow for sign languages to persist. We build on a mathematical model of sign language persistence (i.e. protection from loss) which takes into account the genetic transmission of dea...

(International Sign) Sign languages can be categorized as shared sign languages or deaf community sign languages, depending on the context in which they emerge. It has been suggested that shared sign languages exhibit more variation in the expression of everyday concepts than deaf community sign languages ( Meir, Israel, Sandler, Padden, & Aronoff...

In this paper, we revisit a mathematical model of sign language persistence by Aoki and Feldman (Theor Popul Biol 39(3):358–372, 1991), which investigates the evolution of genes causing deafness, affected by an assortative mating parameter, and the cultural transmission of sign language. To assess their model, we reimplement it as an agent-based si...

Steady-state vowels are vowels that are uttered with a momentarily fixed vocal tract configuration and with steady vibration of the vocal folds. In this steady-state, the vowel waveform appears as a quasi-periodic string of elementary units called pitch periods. Humans perceive this quasi-periodic regularity as a definite pitch. Likewise, so-called...

One of the most controversial hypotheses in cognitive science is the Chomskyan evolutionary conjecture that language arose instantaneously in humans through a single mutation. Here we analyze the evolutionary dynamics implied by this hypothesis, which has never been formalized before. The hypothesis supposes the emergence and fixation of a single m...

Formants are characteristic frequency components in human speech that are caused by resonances in the vocal tract during speech production. They are of primary concern in acoustic phonetics and speech recognition. Despite this, making accurate measurements of the formants, which we dub “the formant measurement problem” for convenience, is as yet no...

Purpose This article critically reviews work on the evolution of speech in the context of motor control. It presents a brief introduction to the field of language evolution, of which the study of the evolution of speech is an integral component, and argues why taking the evolutionary perspective is useful. It then proceeds to review different metho...

One of the most controversial hypotheses in cognitive science is the Chomskyan evolutionary conjecture that language arose instantaneously in our species as the result of a single staggeringly fortuitous mutation. Here we analyze the evolutionary dynamics implied by this hypothesis, which has never been formalized. The theory supposes the emergence...

This paper introduces Parselmouth, an open-source Python library that facilitates access to core functionality of Praat in Python, in an efficient and programmer-friendly way. We introduce and motivate the package, and present simple usage examples. Specifically, we focus on applications in data visualisation, file manipulation, audio manipulation...

The human vocal tract is very different from those of other apes, and it has been proposed that this is due to evolutionary pressures related to speech. There are a number of indications that this is indeed the case, and fossil evidence shows that, for all indications that have been studied so far, Neanderthals are similar to modern humans. This in...

Puppyhood is a very active social and vocal period in a harbour seal’s life Phoca vitulina. An important feature of vocalizations is their temporal and rhythmic structure, and understanding vocal timing and rhythms in harbour seals is critical to a cross-species hypothesis in evolutionary neuroscience that links vocal learning, rhythm perception, a...

Puppyhood is a very active social and vocal period in a harbour seal's life Phoca vitulina. An important feature of vocalizations is their temporal and rhythmic structure, and understanding vocal timing and rhythms in harbour seals is critical to a cross-species hypothesis in evolutionary neuroscience that links vocal learning, rhythm perception, a...

Human language shows combinatoriality in its phonology (both in speech and in sign language) and its grammar, while both types appear to be absent in the communication systems of our closest evolutionary relatives. In this article, we observe that productive combinatoriality is difficult to evolve, because it requires multiple components to be put...

Research Methods in Linguistics - edited by Robert J. Podesva January 2014

Language is the result of two concurrent evolutionary processes: biological and cultural inheritance. An influential evolutionary hypothesis known as the moving target problem implies inherent limitations on the interactions between our two inheritance streams that result from a difference in pace: the speed of cultural evolution is thought to rule...

Arbitrary communication systems can emerge from iconic beginnings through processes of conventionalisation via interaction. Here, we explore whether this process of conventionalisation occurs with continuous, auditory signals. We conducted an artificial signalling experiment. Participants either created signals for themselves, or for a partner in a...

Writing over a century ago, Darwin hypothesized that vocal expression of emotion dates back to our earliest terrestrial ancestors. If this hypothesis is true, we should expect to find cross-species acoustic universals in emotional vocalizations. Studies suggest that acoustic attributes of aroused vocalizations are shared across many mammalian speci...

Macaques do have a speech-ready vocal tract, but lack a speech-ready brain to control it.

Sound systems vary dramatically in their lower-level details as a result of cultural evolution, but the presence of systematic organisation is universal. Why does variation pattern differently at these two levels of abstraction, and what can this tell us about the cognitive mechanisms that underpin human acquisition of speech? We explore an evoluti...

In language, a small number of meaningless building blocks can be combined into an unlimited set of meaningful utterances. This is known as combinatorial structure. One hypothesis for the initial emergence of combinatorial structure in language is that recombining elements of signals solves the problem of overcrowding in a signal space. Another hyp...

The ability to identify emotional arousal in heterospecific vocalizations may facilitate behaviors that increase survival opportunities. Crucially, this ability may orient inter-species interactions, particularly between humans and other species. Research shows that humans identify emotional arousal in vocalizations across multiple species, such as...

Vocal communication is a crucial aspect of animal behaviour. The mechanism which most mammals use to vocalize relies on three anatomical components. First, air overpressure is generated inside the lower vocal tract. Second, as the airstream goes through the glottis, sound is produced via vocal fold vibration. Third, this sound is further filtered b...

Vocal communication is a crucial aspect of animal behavior. The mechanism which most mammals use to vocalize relies on three anatomical components. First, air overpressure is generated inside the lower vocal tract. Second, as the airstream goes through the glottis, sound is produced via vocal fold vibration. Third, this sound is further filtered by...

The question of complexity, as in what makes one language more 'complex' than another, is a long-established topic of debate amongst linguists. Recently, this issue has been complemented with the view that languages are complex adaptive systems, in which emergence and self-organization play major roles. However, few students of the phenomenon have...

For four decades, the inability of nonhuman primates to produce human speech sounds has been claimed to stem from limitations in their vocal tract anatomy, a conclusion based on plaster casts made from the vocal tract of a monkey cadaver. We used x-ray videos to quantify vocal tract dynamics in living macaques during vocalization, facial displays,...

Temporal regularities in speech, such as interdependencies in the timing of speech events, are thought to scaffold early acquisition of the building blocks in speech. By providing on-line clues to the location and duration of upcoming syllables, temporal structure may aid segmentation and clustering of continuous speech into separable units. This h...

Speech is the physical signal used to convey spoken language. Because of its physical nature, speech is both easier to compare with other species’ behaviors and easier to study in the fossil record than other aspects of language. Here I argue that convergent fossil evidence indicates adaptations for complex vocalizations at least as early as the co...

Research on the evolution of human speech and music benefits from hypotheses and data generated in a number of disciplines. The purpose of this article is to illustrate the high relevance of pinniped research for the study of speech, musical rhythm, and their origins, bridging and complementing current research on primates and birds. We briefly dis...

Humans typically combine linguistic and nonlinguistic information to comprehend emotions. We adopted an emotion identification Stroop task to investigate how different channels interact in emotion communication. In experiment 1, synonyms of "happy" and "sad" were spoken with happy and sad prosody. Participants had more difficulty ignoring prosody t...

Artificial languages have gained popularity as a way of empirically testing hypotheses on language evolution and language change (Scott-Phillips & Kirby, 2010), distancing the participants from the biases of their native languages as much as possible. Literature on artificial languages already contains studies on identifying the building blocks in...

Two computer simulations are investigated that model interaction of cultural evolution of language and biological evolution of adaptations to language. Both are agent-based models in which a population of agents imitates each other using realistic vowels. The agents evolve under selective pressure for good imitation. In one model, the evolution of...

I certainly agree with the authors (Everett at al. 2016) that the question whether there is an environmental influence on the sound systems of languages (or on other aspects of language) is worth investigating and that the position that there is no such influence is not empirically founded. Their point that individual counterexamples do not invalid...

Structure of language is not only constrained by cognitive processes, but also by physical aspects of the signalling modality. We test the assumptions surrounding the role which the physical aspects of the signal space will have on the emergence of structure in speech. Here, we use a signal creation task to test whether a signal space and a meaning...

Interest in the origins and evolution of language has been around for as long as language has been around. However, only recently has the empirical study of language come of age. We argue that the field has sufficiently advanced that it now needs its own journal—the Journal of Language Evolution .

In language, recombination of a discrete set of meaningless building blocks forms an unlimited set of possible utterances. How such combinatorial structure emerged in the evolution of human language is increasingly being studied. It has been shown that it can emerge when languages culturally evolve and adapt to human cognitive biases. How the emerg...

When learning language, humans have a tendency to produce more extreme distributions of speech sounds than those observed most frequently: In rapid, casual speech, vowel sounds are centralized, yet cross-linguistically, peripheral vowels occur almost universally. We investigate whether adults' generalization behavior reveals selective pressure for...

This paper argues that an evolutionary perspective is natural when investigating cognitive adaptations related to language. This is because there appears to be correspondence between traits that linguists consider interesting and traits that have undergone selective pressure related to language. The paper briefly reviews theoretical results that sh...

Different linguistic modalities (speech or sign) offer different levels at which signals can iconically represent the world. One hypothesis argues that this iconicity has an effect on how linguistic structure emerges. However, exactly how and why these effects might come about is in need of empirical investigation. In this contribution, we present...

This paper reviews the importance of the interaction between cultural evolution, biological evolution and individual cognition in understanding the cognitive nature of speech sound systems. Because of the effect of cultural evolution, typological properties of languages do not reflect individual cognitive mechanisms directly. In addition, the inter...

Orangutans produce alarm calls called kiss-squeaks, which they sometimes modify by putting a hand in front of their mouth. Through theoretical models and observational evidence, we show that using the hand when making a kiss-squeak alters the acoustics of the production in such a way that more formants per kilohertz are produced. Our theoretical mo...

We present two arguments why physical adaptations for vocalization may be as important as neural adaptations. First, fine control over vocalization is not easy for physical reasons, and modern humans may be exceptional. Second, we present an example of a gorilla that shows rudimentary voluntary control over vocalization, indicating that some neural...

In this abstract we investigate whether emerging sets of signals in cultural evolution experiments show similar structural tendencies as the world's tone languages. An iterated learning experiment (Kirby, Cornish, & Smith, 2008) was conducted with human participants.

Recent work on the interaction between biological and cultural evolution has cast doubt on the effectiveness of the Baldwin effect in explaining cognitive adaptations to language, as culturally transmitted language changes too quickly for biological evolution. It has been argued (Thompson, Smith, & Kirby, 2012) that only minimal learning biases can...

Human speech has combinatorial structure, but it is still unclear how this type of organization emerged in the course of language evolution. There are two positions in the debate about the evolution of combinatorial structure: one stresses the importance of distinctiveness, while the other stresses economy and efficient reuse of building blocks. Di...

In order to understand how humans learn speech imitation without access to detailed articulatory data of other talkers, simulated speech acquisition experiments between two virtual agents were carried out with the goal of maintaining the inter-action between the two as natural as possible. As an outcome, a novel model of infants' vowel acquisition...

This article reports on an experiment in which artificial languages with whistle words for novel objects are culturally transmitted in the laboratory. The aim of this study is to investigate the origins and evolution of combinatorial structure in speech. Participants learned the whistled language and reproduced the sounds with the use of a slide wh...

Interaction between vocal fold vibration and the vocal tract was modeled for vocal tracts with air sacs, and it was investigated how the properties of the upper vocal tract influence the regularity of vocal fold vibration. It was found that for constant vocal tract shape, a first determinant of whether voicing was irregular was lung pressure. Altho...

New perspectives on duality of patterning: Introduction to the special issue - Volume 4 Issue 4 - Bart de Boer, Wendy Sandler, Simon Kirby

This paper reviews how the structure of form and meaning spaces influences the nature and the dynamics of the form-meaning mappings in language. In general, in a structured form or meaning space, not all forms and meanings are equivalent: some forms and some meanings are more easily confused with each other than with other forms or meanings. We fir...

In this paper, the acoustic-perceptual effects of air sacs are investigated. Using an adaptive hearing experiment, it is shown that air sacs reduce the perceptual effect of vowel-like articulations. Air sacs are a feature of the vocal tract of all great apes, except humans. Because the presence or absence of air sacs is correlated with the anatomy...

Most bottom-up models that predict human eye fixations are based on contrast features. The saliency model of Itti, Koch and Niebur is an example of such contrast-saliency models. Although the model has been successfully compared to human eye fixations, we show that it lacks preciseness in the prediction of fixations on mirror-symmetrical forms. The...

The value of the first formant of high back and high front vowels (/u/ and /i/) has been determined for near minimal pairs in a 30-language sample. It is found that for 29 out of 30 languages the average of the first formant is higher for high back vowels than for high front vowels, and that for 26 out of 28 languages the majority of minimal pairs...

In this paper it is investigated what happens in a culturally evolving communication system if children learn faster than adults. An agent based computer model is investigated which contains a population of agents in which vowel systems emerge when individuals play imitation games. These vowel systems are found to be preserved better in the case th...

Speech sounds are organized: they are both categorical and combinatorial and there are constraints on how elements can be recombined. To investigate the origins of this structure, we conducted an iterated learning experiment with humans, studying the transmission of artificial systems of sounds. In this study, participants learn a system of sounds...

This paper investigates the effect of larynx position on the articulatory abilities of a humanlike vocal tract. Previous work has investigated models that were built to resemble the anatomy of existing species or fossil ancestors. This has led to conflicting conclusions about the relation between the evolution of anatomy and the evolution of speech...

A strongly simplified articulatory model, as well as three more realistic models are investigated for the effect of larynx height on the extent of vowel signaling space. The models explore a larger range of larynx positions than previous models, and the use of the convex hull for measuring articulatory abilities is introduced. A short study of huma...

Human speech has been investigated with computer models since the invention of digital computers, and models of the evolution of speech first appeared in the late 1960s and early 1970s. Speech science and computer models have a long shared history because speech is a physical signal and can be modeled accurately. This article gives a brief overview...

An abstract is not available.

The critical period for language acquisition is often assumed to be nothing more than a by-product of development. However, evolutionary computer simulations show that it can be explained as a result of biological evolution (Hurford, 1991). In the present study the aim is not to explain how and why this age sensitivity evolved but to investigate th...

This methodological article serves as an introduction to this special issue, which is meant to encourage more and better interaction between empirical studies and computer modeling with regard to the study of language evolution. We argue that research into the field of language evolution is so complex that computer modeling forms an essential tool...

This paper presents an analysis of the acoustic impedance of primate air sacs and their interaction with the vocal tract. A lumped element model is derived and it is found that the inertance of the neck and the volume of the air sac are relevant, as well as the mass and stiffness of the walls (depending on the tissue). It is also shown that at low...