Research Blogging – Page 2

Arguments against a “prometheus” scenario

The Biological Origin of Linguistic Diversity:

From some of the minds that brought you Chater et al. (2009) comes a new and exciting paper in PlosONE.

Chater et al. (2009) used a computational model to show that biological adaptations for language are impossible because language changes too rapidly through cultural evolution for natural selection to be able to act.

This new paper, Baronchelli et al. (2012), uses similar models to first argue that if language changes quickly then “neutral genes” are selected for because biological evolution cannot act upon linguistic features when they are too much of a “moving target”. Secondly they show that if language changes slowly in order to facilitate coding of linguistic features in the genome, then two isolated subpopulations who originally spoke the same language will diverge biologically through genetic assimilation after they linguistically diverge, which they inevitably will.

The paper argues that because we can observe so much diversity in the world’s languages, but yet children can acquire any language they are immersed in, only the model which supports the selection of “neutral genes” is plausible. Because of this, a hypothesis in which domain general cognitive abilities facilitate language rather than a hypothesis for a biologically specified, special-purpose language system is much more plausible.

A Prometheus scenario:

Baronchelli et al. (2012) use the results of their models to argue against what they call a “Prometheus” scenario. This is a scenario in which “a single mutation (or very few) gave rise to the language faculty in an early human ancestor, whose descendants then dispersed across the globe.”

I wonder if “prometheus” scenario an established term in this context because I can’t find much by googling it. It seems an odd term to use given that Prometheus was the titan who “stole” fire and other cultural tools from the Gods to be used by humans. Since Prometheus was a Titan, he couldn’t pass his genes on to humans, and rather the beginning and proliferation of fire and civilization happened through a process of learning and cultural transmission. I know this is just meant to be an analogy and presumably the promethian aspect of it is alluding to it suddenly happening, but I can’t help but feel that the term “Prometheus scenario” should be given to the hypothesis that language is the result of cultual evolution acting upon domain general processes, rather than one which supports a genetically-defined language faculty in early humans.

References.

Baronchelli A, Chater N, Pastor-Satorras R, & Christiansen MH (2012). The biological origin of linguistic diversity. PloS one, 7 (10) PMID: 23118922

Chater, N., Reali, F., & Christiansen, M. H. (2009). Restrictions on biological adaptation in language evolution. Proceedings of the National Academy of Sciences, 106(4), 1015- 1020.

Taking the “icon” out of Emoticon

For some years now Simon Garrod and Nicolas Fay, among others, have been looking at the emergence of symbolic graphical symbols out of iconic ones using communication experiments which simulate repeated use of a symbol.

Garrod et al. (2007) use a ‘pictionary’ style paradigm where participants are to graphically depict one of 16 concepts without using words, so that their partner can identify it. This process is repeated to see if repeated usage would take advantage of the shared memory of the representation rather than the representation itself to the point where a iconic depiction of an item could become an arbitrary, symbolic one.

Garrod et al. (2007) showed that simple repetition is not enough to allow an arbitrary system to emerge and that feedback and interaction are required between communicators. The amount of interaction afforded to participants was shown to affect the emergence of signs due to a process of grounding. The signs that emerged from this process of interaction were shown to be arbitrary as participants not involved directly in the interaction were shown to have trouble interpreting the outcome signs.

The experimental evidence then shows that icons do indeed evolve into symbols as a consequence of the shared memory of the representation rather than the representation itself. Which is all well and good, but can this process be seen in the real world? YES!

I was talking to a friend on skype and he started typing repeated right round brackets:

))))))))

At first I just thought he had some problem with keys sticking on his keyboard, but after he did it two or three times I finally asked. To which he alluded that that they were smilies. Upon further questioning, it seems that this has become a norm for Russian internet chat that their emoticons have lost their eyes – presumably in the same process as Garrod et al. (2007) showed above.

They have also created an intensification system based on this slightly more arbitrary symbol, where by the more brackets repeated the happier or sadder you are. Among those in the UK and America, the need to intensify an emoticon has stayed well within the rhealms of iconicity with : D meaning “very happy” and D: meaning “oh God, WHHHHHYYYYY”. Japan have a completely different emoticon system altogether which focusses on the eyes: ^_^ meaning happy and u_u meaning sad. Some of argued that this is because in Japan people tend to look to the eyes for emotional cues, whereas Americans tend to look to the mouth, as backed up by SCIENCE.

I’d be interested to see if norms have been established in other countries, either iconic or not.

Refs

Garrod S, Fay N, Lee J, Oberlander J, & Macleod T (2007). Foundations of representation: where might graphical symbol systems come from? Cognitive science, 31 (6), 961-87 PMID: 21635324

Yuki, M., Maddux, W., & Masuda, T. (2007). Are the windows to the soul the same in the East and West? Cultural differences in using the eyes and mouth as cues to recognize emotions in Japan and the United States Journal of Experimental Social Psychology, 43 (2), 303-311 DOI: 10.1016/j.jesp.2006.02.004

Phonemic Diversity and Vanishing Phonemes: Looking for Alternative Hypotheses

In my last post on the vanishing phonemes debate I briefly mentioned Atkinson’s two major theoretical points: (i) that there is a link between phoneme inventory sizes, mechanisms of cultural transmission and the underlying demographic processes supporting these changes; (ii) we could develop a Serial Founder Effect (SFE) model from Africa based on the phoneme inventory size. I also made the point that more work was needed on the details of the first claim before we went ahead and tested the second. To me at least, it seems slightly odd to assume the first model is correct, without really going to any great lengths to disprove it, and then go ahead and commit the statistical version of the narrative fallacy – you find a model that fits the past and use it to tell a story. Still, I guess the best way to get in the New York Times is to come up with a Human Origins story, and leave the boring phonemes as a periphery detail.

Unrealistic Assumptions?

One problem with these unrealistic assumptions is they lead us to believe there is a linear relationship between a linguistic variable (e.g. phoneme inventories) and a socio-demographic variable (e.g. population size). The reality is far more complicated. For instance, Atkinson (2011) and Lupyan & Dale (2010) both consider population size as a variable. Where the two differ is in their theoretical rationale for the application of this variable: whereas the former is interested in how these population dynamics impact upon the distribution of variation, the latter sees social structure as a substantial feature of the linguistic environment in which a language adapts. It is sometimes useful to tell simple stories, and abstract away from the messy complexities of life, yet for the relationships being discussed here, I think we’re still missing some vital points.

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Never mind language, emotions are in a category of their own

A new paper in the journal ‘Emotion’ has presented research which has implications for the evolution of language, emotion and for theories of linguistic relativity.

A new paper in the journal ‘Emotion’ has presented research which has implications for the evolution of language, emotion and for theories of linguistic relativity. The paper, entitled ‘Categorical Perception of Emotional Facial Expressions Does Not Require Lexical Categories’, looks at whether our perception of other people’s emotions depend on the language we speak or if it is universal. The results come from the Max Planck Institute for Psycholinguistics and Evolutionary Anthropology.

Human’s facial expressions are perceived categorically and this has lead to hypotheses that this is caused by linguistic mechanisms.

The paper presents a study which compared German speakers to native speakers of Yucatec Maya, which is a language which has no labels which distinguish disgust from anger. This was backed up by a free naming task in which speakers of German, but not Yucatec Maya, made lexical distinctions between disgust and anger.

The study comprised of a match-to-sample task of facial expressions, and both speakers of German and Yucatec Maya perceived emotional facial expressions of disgust and anger, and other emotions, categorically. This effect was shown to be just as significant across the language groups, as well as across emotion continua (see figure 1.) regardless of lexical distinctions.

The results show that the perception of emotional signals is not the result of linguistic mechanisms which create different lexical labels but instead shows evidence that emotions are subject to their own biologically evolved mechanisms. Sorry Whorfians!

References

Sauter DA, Leguen O, & Haun DB (2011). Categorical perception of emotional facial expressions does not require lexical categories. Emotion (Washington, D.C.) PMID: 22004379

Does Language Shape Thought? Different Manifestations of the Idea of Linguistic Relativity (I)

Does the language we speak influence or even shape the way we think? Last December, there was an interesting debate over at The Economist website with Lera Boroditsky defending the motion, and Language Log’s Mark Liberman against the motion (who IMO, both did a very good job).
The result of the online poll was quite clear: 78% agreed with the motion, while 22% disagreed.

There are, however, three main problems with this way of framing the question: First, it’s not really clear what ‘language’ really is, second, the same goes for “thought”, and third, there are many many ways of how “influencing” and “shaping” something can be conceptualized.
In this post I want to focus on the third problem and present a very useful classification system for hypotheses about linguistic relativity outlined in an article by Phillip Wolff and Kevin J. Holmes, which was published in the current issue Wiley Interdisciplinary Review: Cognitive Science.

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Imitation and Social Cognition (III): Man’s best friend

In my two previous posts (here and here) about imitation and social cognition I wrote about experiments which showed that

1) young children tend to imitate both the necessary as well as the unnecessary actions when shown how to get at a reward, whereas wild chimpanzees only imitate the necessary actions.

And that

2) both 14-month old human infants as well as enculturated, human raised-chimpanzees tend to ‘imitate rationally.’ That is, they tend to be able to differentiate whether an agent chose a specific way of performing an action intentionally, or whether the agent was forced to performing the action in this specific manner by some constraint.

It can be argued that these experiments demonstrate that human infants and young children show an early sensitivity to the communicative intentions of others. That is, they seem to be able to infer that a demonstrator’s specific (and ‘odd’ ) actions are somehow relevant, because she chose this specific manner freely (see also these two extremely interesting posts by the philosopher Pierre Jacob, on which my own post is partly based)

The fact that human-raised chimpanzees also show this sensitivity suggests that enculturation plays an important part in this process.

In a very interesting study, Range et al. (2007) used an experimental setup similar to that of Gergely et al. (2002) (which i described in my second post, here) to test whether other ‘enculturated’ and domesticated animals show the same kind of sensitivity: dogs.

Are mirror neurons the basis of speech perception?

The discovery of Mirror Neurons in Macaque monkeys has lead to theories of the neurophysiological substrate of speech perception being grounded in mirror neurons. This is also relevant to the evolution of speech as if ability to perceive a rapid stream of phonemes is present in species such as macaques then this provides a foundation on which other linguistic abilities could have been built to form language.

A recent paper by Rogalsky et al. (2011) explores these theories by testing the hypothesis that damage to the human mirror system should cause severe deficits in speech perception. This is due to there being a number of recent studies which explore whether the areas of motor neurons are activated during speech perception but these do not address the prediction that patients with lesions in the motor regions (left posterior frontal lobe and/or inferior partiental lobule) should lack an ability to perceive speech.

Patients with Broca’s aphasia are well documented as having severe speech perception and Broca’s area is known to be an area of motor speech perception. This sets up a link between a lesions involving Broca’s area and a difficulty in speech perception. However, despite these problems in speech perception, it has been shown that Broca’s aphasics are quite capable of processing speech sounds. This creates a problem for motor theories of speech perception as it would predict the ability to percieve speech sounds when the lesion lies in Broca’s area. Rogalsky et al. (2011) states that this conclusion may not be so reliable as a lot of the group based studies which these conclusions have been drawn from do not present detailed lesion information but instead rely on clinical diagnosis of Broca’s aphasia to infer lesion location.

Rogalsky et al. (2011) present 5 cases of people with lesions which effect areas of mirror neurons.

Continue reading “Are mirror neurons the basis of speech perception?”

Imitation and Social Cognition in Humans and Chimpanzees (II): Rational Imitation in Human Infants and Human-Raised Chimps

In my last post I wrote about two experiments on imitation in young children and chimpanzees by Lyons et al. (2005) and Horner & Whiten (2005). Their results suggested that young children tend to copy both the ‘necessary’ and the ‘unnecessary’ parts of a demonstrator’s action who shows them how to get a reward out of a puzzle box, whereas chimps only copy the ones necessary to get the reward.

ResearchBlogging.org One important question raised by these experiments was whether these results can only be applied to wild chimpanzees or whether they also hold for enculturated, human-raised chimps. This is an important question because it is possible that chimpanzees raised in these kinds of richly interactive contexts show more sensitivity to human intentionality.

Buttelman et al. (2007) tested just that. They used the “rational imitation” paradigm, which features two conditions

a) the subjects are shown an action in which the specific manner of the action is not purposive and intentional but results from the demonstrator being occupied with something else. For example, he may be carrying something so that he has to use his foot to turn on a light (often called the Hands Occupied Condition).

b) the subjects are shown an action in which the demonstrator chooses a specific manner of doing something on purpose. For example he may have his hands free but still choosto turn on the light with his foot (Hands Free Condition).

taken from Call & Tomasello 2008

Continue reading “Imitation and Social Cognition in Humans and Chimpanzees (II): Rational Imitation in Human Infants and Human-Raised Chimps”

Prairie Dog Communication

istockphoto.com A recent NPR radio show covered the research of the biosemiotician Con Slobodchikoff of the Univeristy of Arizone on prairie dog calls. The piece is very public-orientated, but still might be worth listening to.

We’ve all (I hope) heard of the vervet monkeys, which have different alarm calls for different predators, such as for leopard (Panthera pardus), martial eagle (Polemaetus bellicosus), and python (Python sebae). (Seyfarth et al. 1980) For each of these predators, an inherent and unlearned call is uttered by the first spectator, after which the vervet monkeys respond in a suitable manner – climb a tree, seek shelter, etc. It appears, however, that prairie dogs have a similar system, and that it is a bit more complicated.

Slobodchikoff conducted a study where three girls (probably underpaid, underprivaleged, and underappreciated (under)graduate students) walked through a prairie dog colony wearing shirts of the colors green, yellow, and blue. The call of the first prairie dog to notice them was recorded, after which the prairie dogs all fled into their burrows. The intern then walked through the entire colony, took a break for ten minutes, changed shirts, and did it again.

What is interesting is that the prairie dogs have significantly different calls (important, as they are pretty much exactly the same to human ears) for blue and yellow, but not for yellow and green. This is due to the dichromatic nature of praire dog eyesight (for a full study of the eyesight of retinal photoreceptors of subterranean rodents, consult Schleich et al. 2010). The distinction between blue and yellow is important, however, as there isn’t necessarily any reason that blue people are any more dangerous to praire dogs than yellow ones. “This in turn suggests that the prairie dogs are labeling the predators according to some cognitive category, rather than merely providing instructions on how to escape from a particular predator or responding to the urgency of a predator attack.” (Slobodchikoff 2009, pp. 438)

Another study was then done where two towers were built and a line was strung between them. When cut out shapes were slung down the line, the prairie dogs were able to distinguish a triangle from a circle, but not a circle from a square. So, the prairie dogs are not entirely perfect at encoding information. The conclusion still stands however that more information is encoded in the calls than is entirely relevant to a suitable reaction (unless one were to argue that evolutionary pressure existed on prairie dogs to distinguish blue predators from yellow ones.)

NPR labels this ‘prairiedogese’, which makes me shiver and reminds me of Punxatawney Pennsylvania, where Bill Murray was stuck on a vicious cycle in the movie Groundhog Day, forced every day to watch the mayor recite the translated proclamation of the Groundhog, which of course spoke in ‘groundhogese’. Luckily, however, there won’t be courses in this ‘language’.

References:

Schleich, C., Vielma, A., Glösmann, M., Palacios, A., & Peichl, L. (2010). Retinal photoreceptors of two subterranean tuco-tuco species (Rodentia, Ctenomys): Morphology, topography, and spectral sensitivity The Journal of Comparative Neurology, 518 (19), 4001-4015 DOI: 10.1002/cne.22440

Seyfarth, R., Cheney, D., & Marler, P. (1980). Monkey responses to three different alarm calls: evidence of predator classification and semantic communication Science, 210 (4471), 801-803 DOI: 10.1126/science.7433999

Slobodchikoff CN, Paseka A, & Verdolin JL (2009). Prairie dog alarm calls encode labels about predator colors. Animal cognition, 12 (3), 435-9 PMID: 19116730

Dialects in Tweets

A recent study published in the proceedings of the Empirical Methods in Natural Language Processing Conference (EMNLP) in October and presented in the LSA conference last week found evidence of geographical lexical variation in Twitter posts. (For news stories on it, see here and here.) Eisenstein, O’Connor, Smith and Xing took a batch of Twitter posts from a corpus released of 15% of all posts during a week in March. In total, they kept 4.7 million tokens from 380,000 messages by 9,500 users, all geotagged from within the continental US. They cut out messages from over-active users, taking only messages from users with less than a thousand followers and followees (However, the average author published around 40~ posts per day, which might be seen by some as excessive. They also only took messages from iPhones and BlackBerries, which have the geotagging function. Eventually, they ended up with just over 5,000 words, of which a quarter did not appear in the spell-checking lexicon aspell.

In order to figure out lexical variation accurately, both topic and geographical regions had to be ascertained. To do this, they used a generative model (seen above) that jointly figured these in. Generative models work on the assumption that text is the output of a stochastic process that can be analysed statistically. By looking at mass amounts of texts, they were able to infer the topics that are being talked about. Basically, I could be thinking of a few topics – dinner, food, eating out. If I am in SF, it is likely that I may end up using the word taco in my tweet, based on those topics. What the model does is take those topics and figure from them which words are chosen, while at the same time figuring in the spatial region of the author. This way, lexical variation is easier to place accurately, whereas before discourse topic would have significantly skewed the results (the median error drops from 650 to 500 km, which isn’t that bad, all in all.)

The way it works (in summary and quoting the slide show presented at the LSA annual meeting, since I’m not entirely sure on the details) is that, in order to add a topic, several things must be done. For each author, the model a) picks a region from P( r | ∂ ) b) picks a location from P( y | lambda, v ) and c) picks a distribution over P( Theta | alpha ). For each token, it must a) pick a topic from P( z | Theta ), and then b) pick a word from P( w | nu ). Or something like that (sorry). For more, feel free to download the paper on Eisenstien’s website.

Well, what did they find? Basically, Twitter posts do show massive variation based on region. There are geographically-specific proper names, of course, and topics of local prominence, like taco in LA and cab in NY. There’s also variation in foreign language words, with pues in LA but papi in SF. More interestingly, however, there is a major difference in regional slang. ‘uu’, for instance, is pretty much exclusively on the Eastern seaboard, while ‘you’ is stretched across the nation (with ‘yu’ being only slightly smaller.) ‘suttin’ for something is used only in NY, as is ‘deadass’ (meaning very) and, on and even smaller scale, ‘odee’, while ‘af’ is used for very in the Southwest, and ‘hella’ is used in most of the Western states.

Screen shot 2011-01-12 at 23.41.24 — Dialectical variation for 'very'

More importantly, though, the study shows that we can separate geographical and topical variation, as well as discover geographical variation from text instead of relying solely on geotagging, using this model. Future work from the authors is hoped to cover differences between spoken variation and variation in digital media. And I, for one, think that’s #deadass cool.

Jacob Eisenstein, Brendan O’Connor, Noah A. Smith, & Eric P. Xing (2010). A Latent Variable Model for Geographic Lexical Variation. Proceedings of EMNLP