Basic word order and Uniform Information Density

This week we had a talk by visiting PhD student Luke Maurits about basic word order.  The distributions of basic word orders around the world (Subject-Verb-Object, Subject-Object-Verb etc. ) has been the focus of much attention.  The overwhelming majority of languages have SOV and SVO orders, with fewer having VSO and very small numbers having OVS and OSV.  In order of frequency, this is:

(SOV, SVO) > VSO > (VOS, OVS) > OSV

A standard approach has been to assume that this ordering reflects an ordering of functionality:  Somehow, SOV order is more functional or efficient or intuitive than OSV.  However, Maurits points out that the literature on diachronic change opposes this view.  Languages often change from SOV to VSO or SVO over time, but rarely the other way around (see diagram below).

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Williams Syndrome, Modularity and Language Evolution

Williams Syndrome (WS) is a rare genetic condition which manifests itself as a severe deficit in development and IQ, however it leaves language ability largely unaffected and is, as a result, often cited as evidence for a specific language module (Bellugi et al. 1988), as language can be unaffected despite other mental deficits. This argument has a strong bearing on the evolution of language as it contributes to the debate of whether language evolved for language’s sake or whether it is as the result (an exaptation or spandrel) of general cognitive capability in other areas.

Work by Brock (2007) has shown that the language abilities of people with WS could be predicted by non-linguistic abilities (You could probably argue this of the language abilities of anyone, but that’s another blog post). It has also been shown that language acquisition in WS children is behind that of normal children. Many studies have shown deficits in WS children’s language (reflexive pronouns, grammatical morphems, verb raising, negative wh-sentences) which are generally put down to normal-but-delayed language acquisition as people with the condition will usually pick these grammatical rules up by adolescence.

Perovic and Wexler (2010) suggest that if some grammatical knowledge is shown not to be present in WS children by adolescence, (as is apparently the case with verb raising) then this is evidence to suggest not just ‘normal-but-delayed’ language, but in fact, ‘atypical’ language.

Perovic and Wexler (2010) did a study on 26 children with Williams Syndrome between the ages of 6 – 16. They were tested using picture matching comprehension tasks on passives featuring ‘actional’ verbs and ‘psychological verbs’. The results confirmed what has been seen in previous studies, that WS children can process actional passives with ease, but also showed a previously unreported deficiency in their ability to process psychological verbs.

They also found this deficiency in 5 adult sufferers of WS.

So it seems that the linguistic ability of people with WS is not so exceptional after all.

In the discussion of this paper it is explored as to whether these differences could just be down to the general cognitive impairments which people with developmental problems face. The fact that this question even needs to be discussed is evidence to contradict a ‘language module’ theory. That is that if the deficit in WS children’s passive is a specifically linguistic one then WS can no longer be used as evidence for affected intellectuality but unaffected language, and on the other hand, if it is as a result of general cognitive deficiency, then this is evidence to suggest that it is general cognitive ability that results in much, if not all, linguistic ability in the first place.

References

Bellugi, U. Marks, S. Bihrle, A. and Sbo, H. (1988) Dissociation between language and cognitive functions in Williams Syndrome. In D. Bishop and K. Mogford (Eds.) Language developement in excpetional circumstances (pp. 177 – 189). Hillsdale, NJ: Erlbraum

Brock, J. (2007) Language abilities in Williams syndrome: A critical review. Development and Psychopathology, 19, 97-127.

Perovic A, & Wexler K (2010). Development of verbal passive in Williams syndrome. Journal of speech, language, and hearing research : JSLHR, 53 (5), 1294-306 PMID: 20631227

Michael Tomasello – Why We Cooperate

cross-posted at Shared Symbolic Storage

In this post I will offer a short overview of some aspects of Michael

Tomasello’s latest book „Why We Cooperate,” which is based on his 2008 Tanner Lectures on Human Values.

Tomasello deals with the question how cooperative behaviour and its socio-cognitive foundations arise both in development and during the evolution of the human species. His short text is accompanied by four short commentaries by leading scholars who contributed in important ways to the theory of the evolution and ontogenetic development Tomasello espouses here. These are: psychologist Carol S. Dweck, anthropologist Joan B. Silk, philosopher Brian Skyrms and developmental psychologist Elizabeth Spelke.

In this post I only want to briefly summarize some of the key tenets of Tomasello’s book to offer an introduction to his work on cooperation, whose main impetus it is to have a closer look at the relatively simple and primal cooperative and interactive social behaviour that builds the foundation of human culture.

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Animal Signalling Theory 101 – The Handicap Principle

One of the most important concepts in animal signalling theory, proposed by Amotz Zahavi in a seminal 1975 paper and in later works (Zahavi 1977; Zahavi & Zahavi 1997), is the handicap principle. A general definition is that females have evolved mating preferences for males who display exaggerated ornaments or behaviours that are costly to maintain and develop, and that this cost ensures an ‘honest’ signal of male genetic quality.

As a student I found it quite difficult to identify a working definition for this important type of signal mainly due to the apparent ‘coining fest’ that has taken place over the years since Zahavi outlined his original idea in 1975. For this reason, I have decided to provide a brief outline of the terminological and conceptual differences that exist in relation to the handicap principle in an attempt to help anyone who might be struggling to navigate the literature.

As Zahavi did not define the handicap principle mathematically, a number of interpretations can be found in the key literature due to scholars disagreeing as to the true nature of his original idea. Until John Maynard Smith and Harper simplified and clarified things wonderfully in their 2003 publication Animal Signals, to my knowledge at least four different interpretations of the handicap were being used and explored empirically and through mathematical modelling, each with distinct differences that aren’t all that obvious to grasp without delving into the maths.

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Phonology and Phonetics 101

What I’m going to try and do in this series of posts is follow my phonology module at Cardiff. As such, these posts are essentially my notes on the topic, and may not always come across too clearly. First, I thought it would be useful to give a quick definition of both phonology and phonetics, before moving on to discuss the anatomical organisation of our vocal organs.

Phonetics and Phonology

To begin, phonetics, often referred to as the science of speech sound, is concerned with the physical production, acoustic transmission and perception of human speech sounds (see: phone). One key element of phonetics is the use of transcription to provide a one-to-one mapping between phones and written symbols (something I’ll come back to in a later post). In contrast, phonology focuses on the systematic use of sound in language to encode meaning. So, whereas phonetics is specifically concerned with human speech sounds, phonology, despite having a grounding in phonetics, links in with other levels of language through abstract sound systems and gestures. SIL provides a useful little diagram showing where phonetics and phonology lie in relation to other linguistic disciplines:

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Tool making and Language Evolution

There’s an often cited gap in tool making history in which humans did not advance from simple Oldowan tools (which date back to about 2.5 million years ago) until about 500,000 years ago when progress became much faster. There is much debate as to whether this gap in progress is the result of the cognitive abilities to make more innovative tools or if it was an issue of dexterity.

A recent article by Faisal et al. (2010) “The Manipulative Complexity of Lower Paleolithic Stone Toolmaking” has tried to address these problems by assessing the manipulative complexity of tool making tasks from the Oldowan tools to the more advanced hand axes from much later.

A stone ‘core’ (A) is struck with a hammerstone (B) in order to detach sharp stone ‘flakes’. In Oldowan toolmaking (C, top) the detached flakes (left in photo) are used as simple cutting tools and the core (right in photo) is waste. In Acheulean toolmaking (C, bottom), strategic flake detachments are used to shape the core into a desired form, such as a handaxe. Both forms of toolmaking are associated with activation of left ventral premotor cortex (PMv), Acheulean toolmaking activates additional regions in the right hemisphere, including the supramarginal gyrus (SMG) of the inferior parietal lobule, right PMv, and the right hemisphere homolog of anterior Broca's area: Brodmann area 45 (BA 45).

The following is taken from a press release from Eureka.org:

Researchers used computer modelling and tiny sensors embedded in gloves to assess the complex hand skills that early humans needed in order to make two types of tools during the Lower Palaeolithic period, which began around 2.5 million years ago. The cross-disciplinary team, involving researchers from Imperial College London, employed a craftsperson called a flintnapper to faithfully replicate ancient tool-making techniques.

The team say that comparing the manufacturing techniques used for both Stone Age tools provides evidence of how the human brain and human behaviour evolved during the Lower Palaeolithic period.

The flintnapper who participated in today’s study created two types tools including the razor-sharp flakes and hand-held axes. He wore a data glove with sensors enmeshed into its fabric to record hand and arm movements during the production of these tools.

After analysing this data, the researchers discovered that both flake and hand-held axe manufacturing techniques were equally complex, requiring the same kind of hand and arm dexterity. This enabled the scientists to rule out motor skills as the principal factor for holding up stone tool development.

The team deduced from their results that the axe-tool required a high level of brain processing.

This has implications for language evolution as brain scans from tool makers have shown significant overlap with areas involved in discourse-level language processing as well as complex hand gestures. The study finishes with the following:

…the anatomical overlap of Late Acheulean toolmaking and right hemisphere linguistic processing may reflect the flexible “mapping” of diverse overt behaviors onto shared functional substrates in the brain. This implies that: 1) selection acting on either language or toolmaking abilities could have indirectly favored elaboration of neural substrates important for the other, and 2) archaeological evidence of Paleolithic toolmaking can provide evidence for the presence of cognitive capacities also important to the modern human faculty for language.

Read the original article at PLoS ONE:

http://www.plosone.org/article/info:doi/10.1371/journal.pone.0013718

Cultural and linguistic diversity: evolutionary approaches

Via HENRY:

There’s a special issue of Philosophical Transactions of the Royal Society out on the theme of Cultural and linguistic diversity: evolutionary approaches.

From the introduction:

Evolutionary approaches to cultural change are increasingly influential, and many scientists believe that a ‘grand synthesis’ is now in sight. The papers in this Theme Issue, which derives from a sym- posium held by the AHRC Centre for the Evolution of Cultural Diversity (University College London) in December 2008, focus on how the phylogenetic tree-building and network-based tech- niques used to estimate descent relationships in biology can be adapted to reconstruct cultural histories, where some degree of inter-societal diffusion will almost inevitably be superimposed on any deeper signal of a historical branching process.

Papers:

  • On the shape and fabric of human history – Russell D. Gray, David Bryant, and Simon J. Greenhill

    • Twitter Evolution: Converging Mechanisms in birdsong and human speech

    In my last post, I made reference to the similarities between birdsong and human speech, and how the development of these two might inform us on the evolution of language. So, it comes as a pleasant surprise that there is a new review in Nature Neuroscience on the very topic: Twitter Evolution: converging mechanisms in birdsong and human speech (click here for paper). I haven’t yet had chance to fully read the paper, but I think the following figure is quite instructive of the connective complexity we’re dealing with:

    Mathematical Modelling 101 – Evolutionary Game Theory

    Game Theory was fist applied to evolution by John Maynard-Smith and George Price in 1973. It differs from traditional game theory is that it focusses on dynamics of strategy change more than the properties of strategy equilibria, although equilibria still exist within EGT but are know as Evolutionary Stable Strategies as opposed to Nash Equilibria.

    Dove-Hawk

    Imagine a situation in which 2 members of a species come into conflict over a resource. Within this conflict each animal has the optional to ‘fight’, ‘display’ or ‘run away’. There are 2 strategies within this species, either the Dove strategy or the Hawk strategy. In the Dave strategy, upon meeting someone also adopting the Dove strategy both “Doves” display and share the resource or upon meeting a “Hawk” the Dove runs away. Adopting the Hawk strategy entails always fighting. So upon meeting a Dove the Hawk will fight and the Dove will run away and the Hawk will take all of the resource, and upon meeting another Hawk, both will fight and one will win out. On average across many interactions with other Hawks, the payoff gained ends up being (v/2)-c where v=value of resource and c=cost.

    Dove Hawk
    Dove v/2, v/2 v, 0
    Hawk 0, v (v-c)/2, (v-c)/2

    The question to ask of this game is, given values v and c, which strategy will evolutionarily win out?

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