10 – Replicated Typo

Talk to the Virtual Hands

A new paper in PlosOne has used new fancy research methods to look at whether humans are more capable of describing a word using just spoken communication, or whether the use of gesture also helps. This research is pertinent to the field of language evolution because it might help us understand if spoken language co-evolved with gesture as well as helping us understand how language is processed in the brain.

This new study builds on previous research in this area by using avatars in a virtual reality setting. Participants were either in control of the movements of their avatar, or not.

The study found that participants were much more successful in communicating concepts when the speaker was able to use their own gestures when explaining a concept using spoken language. The body language of the listener also impacted success at the task, showing the need for nonverbal feedback from the listener.

It’s worth noting that the primary purpose of this research wasn’t to find if gesture is helpful in communication (though that is certainly interesting and worthwhile) but rather whether using virtual reality is fruitful in these kinds of experiments.

The press release discusses some of the problems with using avatars:

The researchers note that there are limitations to nonverbal communication in virtual reality environments. First, they found that participants move much less in a virtual environment than they do in the “real world.” They also found that the perspective of the camera in the virtual environment affected the results.

Lead author, Dr. Trevor Dodds maintains, “this research demonstrates that virtual reality technology can help us gain a greater understanding of the role of body gestures in communication. We show that body gestures carry extra information when communicating the meaning of words. Additionally, with virtual reality technology we have learned that body gestures from both the speaker and listener contribute to the successful communication of the meaning of words. These findings are also important for the development of virtual environments, with applications including medical training, urban planning, entertainment and telecommunication.”

The work was led by Dr. Trevor Dodds at the Max Planck Institute for Biological Cybernetics in Germany.

References
Dodds TJ, Mohler BJ, Bu¨ lthoff HH (2011) Talk to the Virtual Hands: Self-Animated Avatars Improve Communication in Head-Mounted Display Virtual Environments. PLoS ONE 6(10): e25759. doi:10.1371/journal.pone.0025759

Cultural differences in lateral transmission: Phylogenetic trees are OK for Linguistics but not biology

An article in PLos ONE debunks the myth that hunter-gatherer societies borrow more words than agriculturalist societies. In doing so, it suggests that horizontal transmission is low enough for phylogenetic analyses to be a valid linguistic tool.

Lexicons from around 20% of the extant languages spoken by hunter-gatherer societies were coded for etymology (available in the supplementary material). The levels of borrowed words were compared with the languages of agriculturalist and urban societies taken from the World Loanword Database. The study focussed on three locations: Northern Australia, northwest Amazonia, and California and the Great Basin.

In opposition to some previous hypotheses, hunter-gatherer societies did not borrow significantly more words than agricultural societies in any of the regions studied.

The rates of borrowing were universally low, with most languages not borrowing more than 10% of their basic vocabulary. The mean rate for hunter-gatherer societies was 6.38% while the mean for 5.15%. This difference is actually significant overall, but not within particular regions. Therefore, the authors claim, “individual area variation is more important than any general tendencies of HG or AG languages”.

Interestingly, in some regions, mobility, population size and population density were significant factors. Mobile populations and low-density populations had significantly lower borrowing rates, while smaller populations borrowed proportionately more words. This may be in line with the theory of linguistic carrying capacity as discussed by Wintz (see here and here). The level of exogamy was a significant factor in Australia.

The study concludes that phylogenetic analyses are a valid form of linguistic analysis because the level of horizontal transmission is low. That is, languages are tree-like enough for phylogenetic assumptions to be valid:

“While it is important to identify the occasional aberrant cases of high borrowing, our results support the idea that lexical evolution is largely tree-like, and justify the continued application of quantitative phylogenetic methods to examine linguistic evolution at the level of the lexicon. As is the case with biological evolution, it will be important to test the fit of trees produced by these methods to the data used to reconstruct them. However, one advantage linguists have over biologists is that they can use the methods we have described to identify borrowed lexical items and remove them from the dataset. For this reason, it has been proposed that, in cases of short to medium time depth (e.g., hundreds to several thousand years), linguistic data are superior to genetic data for reconstructing human prehistory “

Excellent – linguistics beats biology for a change!

However, while the level of horizontal transmission might not be a problem in this analysis, there may be a problem in the paths of borrowing. If a language borrows relatively few words, but those words come from many different languages, and may have many paths through previous generations, there may be a subtle effect of horizontal transition that is being masked. The authors acknowledge that they did not address the direction of transmission in a quantitative way.

A while ago, I did study of English etymology trying to quantify the level of horizontal transmission through time (description here). The graph for English doesn’t look tree-like to me, perhaps the dynamics of borrowing works differently for languages with a high level of contact:

Claire Bowern, Patience Epps, Russell Gray, Jane Hill, Keith Hunley, Patrick McConvell, Jason Zentz (2011). Does Lateral Transmission Obscure Inheritance in Hunter-Gatherer Languages? PLoS ONE, 6 (9) : doi:10.1371/journal.pone.0025195

Does a Smart Phone make Smart Science?

A new paper in plos one, published today, has shown that experiments on human cognition needn’t be confined to the lab.

Experiments on human cognitive abilities, such as language, often rely on testing small and homogeneous groups of volunteers (mostly undergraduate students) coming to research facilities where they are asked to participate in behavioral experiments. This arrangement is not ideal as your sample will not be representative of the population as a whole and will also be restricted as there is only so many participants that money and time will allow you to get into the lab to be tested.

This new research by Dufau et al. shows that the sampling limitations which laboratory experiments produce can be overcome by using smartphones. Using smart phone technology, data can be collected for cognitive science experiments from thousands of subjects from all over the world.

To illustrate how this can be done the authors carried out a large-scale study using iPhone and iPads. This was a linguistic study looking at people’s ability to distinguish words from similar non-words.

The project, which began in December 2010 has managed to collect data from 4,157 subjects in just 4 months! This can be compared with the English Lexicon Project which acquired a similar volume of data using traditional methods which took more than 3 years.

The data was collected using applications which were produced in seven languages (English, Basque, Catalan, Dutch, French, Malay, Spanish). Smartphones can also support studies in alphabets other than Roman including Chinese, Greek, and Japanese. This creates the opportunity to create large-scale cross linguistic studies without even having to move from behind your desk.

Whilst the example here is linguistic there is every reason that smart phones can be implemented in looking at how universal other areas of cognitive behaviour are. Or even neurosceince and experimental philosophy. I wonder if it would be possible to carry out experiments using transmission chains using smart phones.

However, I do worry that using things like iPhones will have the same problems as using things like mechanical turk, as it means that experimenters will not be able to make sure that participants are carrying out the tasks properly and removes quite a lot of control. Smartphones are also still a luxury and therefore only people within a certain socio-economic class will have smartphones, so maybe these methods may not reach such a wide audience, which seems to be why they’re being proposed in the first place.

The authors of the paper are hailing smartphones “a potential revolution in cognitive science” but only time will tell if this really kicks off!

Reference

Stephane Dufau, Jon Andoni Dun abeitia, Carmen Moret-Tatay, Aileen McGonigal, David Peeters, F.-Xavier Alario, David A. Balota, Marc Brysbaert, Manuel Carreiras, Ludovic Ferrand, Maria Ktori, Manuel Perea, Kathy Rastle, Olivier Sasburg, Melvin J. Yap, J (2011). Smart Phone, Smart Science: How the Use of Smartphones Can Revolutionize Research in Cognitive Science PlosOne, 6 (9) : 10.1371/journal.pone.0024974

Sonority and Sex: Why smaller communities are louder

Through this post on Sprogmuseet about Atkinson’s analysis of the out of Africa hypothesis, I found an article by Ember & Ember (2007) (who also quantified the link between colour lexicon size and distance from the equator, see my post here) on Sonority and climate. The article extends work by Fought et al. (2004) which finds that a language’s sonority is related to climate. Sonority is a measure of amplitude (loudness) as is greater for vowels than for consonants (for example, see here). Basically, the warmer the climate, the greater the sonority of the phoneme inventory of the population. The theory is that “people in warmer climates generally spend more time outdoors and communicate at a distance more often than people in colder climates”.

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Linguistic diversity and traffic accidents

I was thinking about Daniel Nettle’s model of linguistic diversity which showed that linguistic variation tends to decline even with a small amount of migration between communities. I wondered if statistics about population movement would correlate with linguistic diversity, as measured by the Greenberg Diversity Index (GDI) for a country (see below). However, this is a cautionary tale about obsession and use of statistics. (See bottom of post for link to data).

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A random walk model of linguistic complexity

EDIT: Since writing this post, I have discovered a major flaw with the conclusion which is described here.

One of the problems with large-scale statistical analyses of linguistic typologies is the temporal resolution of the data. Because we only typically have single measurements for populations, we can’t see the dynamics of the system. A correlation between two variables that exists now may be an accident of more complex dynamics. For instance, Lupyan & Dale (2010) find a statistically significant correlation between a linguistic population’s size and its morphological complexity. One hypothesis is that the language of larger populations are adapting to adult learners as they comes into contact with other languages. Hay & Bauer (2007) also link demography with phonemic diversity. However, it’s not clear how robust these relationships are over time, because of a lack of data on these variables in the past.

To test this, a benchmark is needed. One method is to use careful statistical controls, such as controlling for the area that the language is spoken in, the density of the population etc. However, these data also tend to be synchronic. Another method is to compare the results against the predictions of a simple model. Here, I propose a simple model based on a dynamic where cultural variants in small populations change more rapidly than those in large populations. This models the stochastic nature of small samples (see the introduction of Atkinson, 2011 for a brief review of this idea). This model tests whether chaotic dynamics lead to periods of apparent correlation between variables. Source code for this model is available at the bottom.

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Creative cultural transmission as chaotic sampling

Last week I attended a lecture by Liz Bradley on chaos. Chaos has been used to create variations on musical and dance sequences (Dabby, 2008; Bradley & Stuart, 1998). I was interested to see whether this technique could be iterated and applied to birdsong or other culturally transmitted systems. I present a model of creative cultural transmission based on this.

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Cultural Evolution and the Impending Singularity

Prof. Alfred Hubler is an actual mad professor who is a danger to life as we know it. In a talk this evening he went from ball bearings in castor oil to hyper-advanced machine intelligence and from some bits of string to the boundary conditions of the universe. Hubler suggests that he is building a hyper-intelligent computer. However, will hyper-intelligent machines actually give us a better scientific understanding of the universe, or will they just spend their time playing Tetris?

Let him take you on a journey…

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Academic Networking

Who are the movers and shakers in your field? You can use social network theory on your bibliographies to find out:

Today I learned about some studies looking at social networks constructed from bibliographic data (from Mark Newman, see Newman 2001 or Said et al. 2008) . Nodes on a graph represent authors and edges are added if those authors have co-authored a paper.

I scripted a little tool to construct such a graph from bibtex files – the bibliographic data files used with latex. The Language Evolution and Computation Bibliography – a list of the most relevant papers in the field – is available in bibtex format.

You can look at the program using the online Academic Networking application that I scripted today, or upload your own bibtex file to find out who the movers and shakers are in your field. Soon, I hope to add an automatic graph-visualisation, too.

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Laryngeal Air Sacs

So, I got a request from a friend of mine to make an abstract on the fly for a poster for Friday. I stayed up until 3am and banged this out. Tonight, I hope to write the poster justifying it into being. A lot of the work here builds on Bart de Boer’s work, with which I am pretty familiar, but much of it also started with a wonderful series of posts over on Tetrapod Zoology. Rather than describe air sacs here, I’m just going to link to that – I highly suggest the series!

Here’s the abstract I wrote up, once you’ve read that article on air sacs in primates. Any feedback would be greatly appreciated – I’ll try to make a follow-up post with the information that I gather tonight and tomorrow morning on the poster, as well.

Re-dating the loss of laryngeal air sacs in hominins

Laryngeal air sacs are a product of convergent evolution in many different species of primates, cervids, bats, and other mammals. In the case of Homo sapiens, their presence has been lost. This has been argued to have happened before Homo heidelbergensis, due to a loss of the bulla in the hyoid bone from Austrolopithecus afarensis (Martinez, 2008), at a range of 500kya to 3.3mya. (de Boer, to appear). Justifications for the loss of laryngeal air sacs include infection, the ability to modify breathing patterns and reduce need for an anti-hyperventilating device (Hewitt et al, 2002), and the selection against air sacs as they are disadvantageous for subtle, timed, and distinct sounds (de Boer, to appear). Further, it has been suggested that the loss goes against the significant correlation of air sac retention to evolutionary growth in body mass (Hewitt et al., 2002).

I argue that the loss of air sacs may have occurred more recently (less than 600kya), as the loss of the bulla in the hyoid does not exclude the possibility of airs sacs, as in cervids, where laryngeal air sacs can herniate between two muscles (Frey et al., 2007). Further, the weight measurements of living species as a justification for the loss of air sacs despite a gain in body mass I argue to be unfounded given archaeological evidence, which suggests that the laryngeal air sacs may have been lost only after size reduction in Homo sapiens from Homo heidelbergensis.

Finally, I suggest two further justifications for loss of the laryngeal air sacs in homo sapiens. First, the linguistic niche of hunting in the environment in which early hominin hunters have been posited to exist – the savannah – would have been better suited to higher frequency, directional calls as opposed to lower frequency, multidirectional calls. The loss of air sacs would have then been directly advantageous, as lower frequencies produced by air sac vocalisations over bare ground have been shown to favour multidirectional over targeted utterances (Frey and Gebler, 2003). Secondly, the reuse of air stored in air sacs could have possibly been disadvantageous toward sustained, regular heavy breathing, as would occur in a similar hunting environment.

References:

Boer, B. de. (to appear). Air sacs and vocal fold vibration: Implications for evolution of speech.

Fitch, T. (2006). Production of Vocalizations in Mammals. Encyclopedia of Language and Linguistics. Elsevier.

Frey, R, & Gebler, A. (2003). The highly specialized vocal tract of the male Mongolian gazelle (Procapra gutturosa Pallas, 1777–Mammalia, Bovidae). Journal of anatomy, 203(5), 451-71. Retrieved June 1, 2011, from http://www.pubmedcentral.nih.gov/articlerender.fcgi?artid=1571182&tool=pmcentrez&rendertype=abstract.

Frey, Roland, Gebler, Alban, Fritsch, G., Nygrén, K., & Weissengruber, G. E. (2007). Nordic rattle: the hoarse vocalization and the inflatable laryngeal air sac of reindeer (Rangifer tarandus). Journal of Anatomy, 210(2), 131-159. doi: 10.1111/j.1469-7580.2006.00684.x.

Martínez, I., Arsuaga, J. L., Quam, R., Carretero, J. M., Gracia, a, & Rodríguez, L. (2008). Human hyoid bones from the middle Pleistocene site of the Sima de los Huesos (Sierra de Atapuerca, Spain). Journal of human evolution, 54(1), 118-24. doi: 10.1016/j.jhevol.2007.07.006.

Hewitt, G., MacLarnon, A., & Jones, K. E. (2002). The functions of laryngeal air sacs in primates: a new hypothesis. Folia primatologica international journal of primatology, 73(2-3), 70-94. Retrieved from http://www.ncbi.nlm.nih.gov/pubmed/12207055.

Sound good? I hope so! That’s all for now.