Input variability as a mechanism for social structure determination of linguistic complexity

Mark Atkinson

Abstract: While non-linguistic features of a speech community have been shown to correlate with degrees of linguistic complexity, the explanatory mechanism(s) by which they could have such an influence has not yet been convincingly identified. Currently the most popular explanation appeals to the differences between adult and child learning. Larger languages, for example, are thought to attract higher proportions of non-native speakers, who then simplify their language through greater levels of analysis and learning error.

This is not the only possible explanation, however, and I will present the results from a recent experiment which finds support for the alternative candidate mechanism of input variability. 20 participants were trained on a morphologically-complex miniature language in two conditions: one in which aural input was provided by a single native speaker, and another in which they received their input from three speakers. Despite the training data being identical in both conditions, learners in the single-speaker condition demonstrated a more successful acquisition of the morphological system. As other aspects of the target language were learned equally well in both conditions, it does not appear that lower levels of input variability simply aid language acquisition in general.

This difference in performance between the conditions appears to be due to the participants learning their training data in systematically different ways. There are indications that the multiple-speaker condition promoted the more holistic learning of the training data utterances, so reducing the learners’ ability to generalise. I will describe the evidence for this and offer some possible explanations, before finally discussing some options for future research.

Tue 10th December, 11.30-1.00, B21 7 George Square

Functionalism and Its Discontents

Kevin Stadler

Functional explanations of language features have not only regained
appeal in the past decades by their reframing in evolutionary (read:
selectionist) terms, they’ve also recently been joined by newly
discovered relationships between linguistic features such as
grammatical and phonological complexity and non-linguistic features
such as the size of the speech community. Crucially, both functional
features in individual languages as well as probabilistic universals
(whether of the newfangled or the more traditional Greenbergian type),
while being synchronic in nature, require diachronic explanations to
go from description (or correlation) to explanation (or causation):
just because something is apparently functional does not mean we can
account for its existence or prevalence simply based on this function.

Functional explanations have a long history within the traditional
study of language change, and an equally long (and illustrious) list
of adversaries and fervent critics, from Jespersen over Weinreich et
al. and Lass to Haspelmath and back again. In this talk I want to
provide an overview of these critiques, both to raise awareness of the
problematic nature of selectionist explanations, but also to explore
possible ways out of the numerous functionalist traps.

Time allowing I will touch upon topics such as the actuation problem,
unmoved movers, Saussure’s firewall, ‘boring’ universals, frequency
effects, emergent grammar, process theories of language change and -
more fundamentally – the uneasy relationship between functional
accounts of language features and the arbitrariness of language.

Motivated vs. conventional systematicity: Implications for language learning and the structure of the lexicon

Alan Nielsen

Given that the task of language learning involves pressures for both learnability and communicative accuracy, one might expect that, contra to the linguistic dogma of arbitrariness, systematic mappings between signals and meanings might be easier to learn. In the past decade two streams of research — one exploring systematic signal-meaning mappings that are conventional, and one exploring mappings that are sound-symbolic or otherwise motivated by the structure of the language learner/environment. In this talk I will present the results of an experiment where participants learned a language that used either motivated (vowel height/frontness–> size; consonant plosivity –> shape) or conventional associations between signals and meanings. The results of this experiment suggest that sound-symbolic associations are easier to learn than conventional associations, and that at least part of this benefit arises from an early advantage for motivated associations. However, the results also serve to demonstrate how little is known about what consonantal and vowel characteristics drive sound-symbolic associations.

The elimination of unpredictable variation is dependent on speaker identity

Olga Feher

Natural languages do not normally exhibit unpredictable variation, which is when an object is labelled by two or more words that are used interchangeably in a random manner. Synonyms are common but their use is usually conditioned on some social or contextual variable. Therefore, unpredictable variation is a good tool to study language evolution and learners’ biases. We trained participants on a miniature artificial language using a word learning task to test the effects of speaker identity on the elimination of unpredictable variation. The spoken input language contained two labels for each object presented, one label used twice as often as the other but the variation was distributed differently across 1-3 speakers. There were four conditions: in one, participants heard a single speaker name all objects; in the second condition 3 speakers named objects with variable usage; in the third condition 3 speakers used the labels categorically: two speakers using one label all the time and the third speaker using the other label consistently; and in the last condition is like the third with the odd label always used by the same “odd ball” speaker. We found that participants who received variable input from all the speakers tended to probability match, whereas when variation came from between speakers, participants were much more likely to regularise in their word recall. This can be due to conformity effects or learning the categorical behaviour of speakers.

Semantic structure and emerging conventions in silent gesture

Marieke Schouwstra

When individuals do not share a common language, they cannot reliably use existing linguistic conventions when they communicate. This is is the case in, e.g., unsupervised second language acquisition and home sign. I will briefly review observations from these systems, showing that they are largely governed by semantic organisational principles (Jackendoff, 2002).

Subsequently, I will present results from my silent gesture experiments, in which naive participants were asked to describe events using only gesture and no speech (similarly to Goldin-Meadow et al., 2008). I will show that, like unsupervised second language learners and homesigners, silent gesturers shape utterances flexibly and according to their meaning:

– Whereas for simple events that involve motion through space (e.g., ‘pirate smashes guitar’), SOV basic word order is preferred, more abstract intensional events (e.g., ‘pirate searches guitar’) give rise to a different ordering: SVO.

– When participants are asked to describe events that take place at some other time than now (e.g., ‘a pirate smashes a guitar at three o’clock’), they systematically apply a strategy similar to that observed in adult second language learners and homesigners, in which the temporal information precedes—and never interrupts—the event information (such as in ‘3 O’CLOCK-PIRATE-GUITAR-THROW’). This mirrors the semantic representation of a temporally displaced event.

These observations strengthen the hypothesis that in language systems without full syntax, meaning determines structure, suggesting an evolutionary scenario in which semantic structure preceded syntactic structure. However, how and why have these early semantic stages of language evolved such that the relationship between utterance structure and semantic structure became obscured? In other words, how did language go from semantic organising principles to fully functioning syntactic rules? I will conclude with some ideas how to investigate this question empirically, using various silent gesture lab experiments that incorporate repeated social transmission.

Klaas Seinhorst – The learnability of phoneme inventories

I will present my PhD project “The learnability of phoneme inventories”, which I started at the University of Amsterdam in September 2012. The starting point of my project was the observation that languages have strong preferences for certain sets of plosive sounds, while other sets are extremely rare. In the experiments I plan to conduct, human participants will learn sets of linguistic stimuli analogous to sound systems – both frequent and infrequent ones; using iterated learning, I will monitor the evolution of these sets and compare the outcomes to typological data. If the experimental findings comply with the typological results, this would point to an important role of learning biases in phonological typology.

Model Fitting and Prediction for Language Evolution: Quirks and Opportunities
Bill Thompson

Questions concerning the origins of linguistic structures are increasingly being studied by means of artificial language learning experiments. Central to this enterprise is the drive to uncover cognitive biases that shape the evolution of linguistic systems. A particularly promising growth area in this field is the use of cognitive model fitting techniques. In this talk I’ll argue that, perhaps unlike comparable topics in cognitive science, questions of language evolution must be seen in the light of cultural evolution. This feature at once poses potentially unique difficulties and exciting opportunities in experimental design and model fitting. I’ll consider several techniques that may help maximise confidence in the inferences we can draw, from experimental data, about language learning biases and their consequences for population-level linguistic phenomena. In particular I hope to show that the quirks of studying a culturally learned behaviour, and the opportunities to make predictions about culture by harnessing information in experimental learning data, are served equally by the same approach.

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Title: The cultural evolution of sign languages in the laboratory: from pantomime to linguistic system?

Speaker: Simon Kirby

Place: B21, 7 George Square

Date: 1st October, 11.00-12.30

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See you there, I hope!

Simon

Experimental and theoretical models of cultural evolution

Marius Kempe, University of Durham

Abstract:
I will talk about two experimental and two theoretical models of cultural evolution. In the first experiment, I test the hypothesis that increasing group size speeds up cultural accumulation, using a novel puzzle-solving task and within a transmission chain design. I find support for this hypothesis, in contrast with previous experiments. In the second experiment, also using a transmission chain design, I examine perceptual errors in recreating Acheulean handaxes and ask whether such errors can account for the variability of Acheulean technology over time. Using the accumulated copying error model to compare the experimental data to archaeological records, I conclude that perceptual errors alone were likely not the driving force behind Acheulean evolution. In the first theoretical study, I present models of cultural differences between populations and of cumulative culture, which build on existing models and accord with empirical data. I then show that the models, when combined, have two qualitative regimes which may correspond to human and nonhuman culture. In the second theoretical study, I present a ‘fundamental theorem of cultural selection’, an parallel to Fisher’s Fundamental Theorem of Natural Selection for cultural evolution. I discuss how this theorem formalizes and sheds light on cultural evolutionary theory.