Tag: language

The Problem With a Purely Adaptationist Theory of Language Evolution

According to the evolutionary psychologist Geoffrey Miller and his colleagues (e.g Miller 2000b), uniquely human cognitive behaviours such as musical and artistic ability and creativity, should be considered both deviant and special. This is because traditionally, evolutionary biologists have struggled to fathom exactly how such seemingly superfluous cerebral assets would have aided our survival. By the same token, they have observed that our linguistic powers are more advanced than seems necessary to merely get things done, our command of an expansive vocabulary and elaborate syntax allows us to express an almost limitless range of concepts and ideas above and beyond the immediate physical world. The question is: why bother to evolve something so complicated, if it wasn’t really all that useful?

Miller’s solution is that our most intriguing abilities, including language, have been shaped predominantly by sexual selection rather than natural selection, in the same way that large cumbersome ornaments, bright plumages and complex song have evolved in other animals. As one might expect then, Miller’s theory of language evolution has been hailed as a key alternative to the dominant view that language evolved because it conferred a distinct survival advantage to its users through improved communication (e.g. Pinker 2003). He believes that language evolved in response to strong sexual selection pressure for interesting and entertaining conversation because linguistic ability functioned as an honest indicator of general intelligence and underlying genetic quality; those who could demonstrate verbal competence enjoyed a high level of reproductive success and the subsequent perpetuation of their genes. Continue reading “The Problem With a Purely Adaptationist Theory of Language Evolution”

Some Links #16: Why I want to Falcon Punch (some) BBC Science Writers

I’m not normally one for violent resolutions to sloppy science, but in taking inspiration from one such perpetrator I’m promoting a Falcon Punch policy. Above is a graphical example of a successful Falcon Punch: the goal being to hurl your target onwards and upwards into a flaming ball of scientific shame.

Space is the final frontier for evolution, study claims. I had planned on writing a more substantial article on how yet another science writer, in this case one Howard Falcon-Lang, is claiming that Darwin has once again been felled by a new study. Greg Laden, however, beat me to the punch with a damning critique:

Continue reading “Some Links #16: Why I want to Falcon Punch (some) BBC Science Writers”

Evolution of Colour Terms: 10 Universal Patterns are not Evidence for Innate Constraints

In a series of posts, I’ve been discussing constraints on the evolution of colour terms. Here, I discuss the role of drift and also argue that universal patterns are not necessarily good evidence for innate constraints. For the full dissertation and references, go here.

Drift

An important point which has not been highlighted in the literature is the drift introduced by cultural transmission.  Perceptual systems are noisy, and change over lifetimes.  Therefore, systems of categorising these perceptions may drift over time.  However, if concepts are shared, this drift is influenced by more than one system.  This may cause a different kind of drift from a stand-alone system for self-thought.  Communication has an additional semantic bottleneck which self-though does not have.  Using language for self thought, if you don’t know a label, you can make one up.

However, for communication, this won’t work.  For example, in models of cultural transmission (e.g., Steels & Belpaeme, 2005) agents do create new labels but, importantly, accept the speaker’s label when available.  That is, communicative systems are more flexible than systems for self-thought (communicators must be more willing to change their minds), and so are more subject to drift.  The drift allows the system to move around the possible space of coding efficiency and object categorisation efficiency.  Peaks in these landscapes will attract the drift, hence environmental and perceptual constraints being projected into language.

Although systems of colour categorisation for self-thought may be more efficient if they were constrained by the environment, shared cultural systems are more likely to reflect constraints in the environment because they are more flexible.  That is, perceptual constraints have projected themselves into language because of a communicative pressure, rather than a perceptual or environmental pressure.

I suggest that this drift, together with an ability for categories to warp perceptual spaces, would mean that individuals converge on a shared perceptual system.  If comprehension involves the activation of perceptual representations, then communication involves individuals reaching similar perceptual representations or, in a perfect world, activation of the same neural substrates.  Therefore, a population with a shared perceptual system would be able to communicate much more effectively.  In this sense, Embodied systems improve communicative success, whereas the same effect is not necessarily true of Symbolist systems. Furthermore, this drift means that populations can still converge on similar solutions, without having to assume that Universal biases are the main driving force.  It has been argued that the similarities in colour categorisation between cultures contradicts Relativism, which would predict a large variation in colour categorisation between cultures (e.g., Belpaeme & Bleys, 2005).  I argue that this inference is not necessarily valid.

Summary

This series of posts has shown that a wide range of factors constrain the categorisation of colour, including the physiology of perception, the environment and cultural transmission.  Why is there evidence for Colour Terms being adapted to so many domains?

This study considered the idea that categorisation acquired by individuals can feed back into perception and itself become a constraint both on the development of categorisation, the environment and genetic inheritance.  In this sense, the feedback from categorisation allows Niche Construction dynamics to apply to linguistic categorisations.  It was argued that this dynamic fits with the Cultural implication of an Embodied account of language comprehension.  That is, this study has concluded, similarly to Kirby et al. (2007), that universal patterns across populations do not necessarily imply strong innate biases.  This was done by arguing that Cultural, Embodied systems tend to drift towards better representations of the real world, which involves better coherence with perceptual and environmental constraints, creating cross-cultural patterns.  Furthermore, an Embodied approach to cultural dynamics incorporating a mechanism for perceptual warping predicts that the perceptual spaces of individuals can be synchronised through language to achieve better communication.

Steels, L., & Belpaeme, T. (2005). Coordinating perceptually grounded categories through language: A case study for colour Behavioral and Brain Sciences, 28 (04) DOI: 10.1017/S0140525X05000087

Belpaeme, T. (2005). Explaining Universal Color Categories Through a Constrained Acquisition Process Adaptive Behavior, 13 (4), 293-310 DOI: 10.1177/105971230501300404

Kirby, S., Dowman, M., & Griffiths, T. (2007). Innateness and culture in the evolution of language Proceedings of the National Academy of Sciences, 104 (12), 5241-5245 DOI: 10.1073/pnas.0608222104

Evolution of Colour Terms: 9 Niche Construction

In a series of posts, I’ve been discussing constraints on the evolution of colour terms. For the full dissertation and references, go here.

This section reiterates how a link between linguistic categories and perception fits into Niche Construction Theory.  If concepts can influence perception, and people share the same concepts, their perceptions will become synchronised.  This would render them more effective at communication, since referents would be perceived as similar (‘red’ can refer to the same domain of entities for each individual).  Furthermore, it may render them more able to co-operatively build a better model of the actual environment (for instance, describing an unseen danger, or researching physics).  However, this will only be true if language is grounded in constraints that come from the actual environment.  If this were not the case, apart from being inefficient at describing the actual environment, a language may drift to influence the perceived environment in a way that results in a worse fit with the actual environment.

Returning to the constraints diagram (above), note that the influence of categorisation continues, through action, to change the environment.  In other words, if language influences the perceived environment and facilitates communication, then it may also facilitate the way we change the actual environment.  In this sense, language’s influence on perception can be regarded as a form of Niche Construction (Laland, Odling-Smee & Feldman, 2000).  Therefore, not only does language become better at describing the actual environment, but the environment becomes better suited to being described by language.  This creates a better fit between perceived and actual environments and possibly increases the fitness of language users.  Essentially, then, this study presents evidence for language-specific niche construction where language can influence the environment.  This dynamic would be a consequence of an Embodied system, and more efficient as part of an Embodied system than a Symbolist account.  I therefore argue that the Embodied account is supported.

As an example of this dynamic, Hansen et al. (2006) showed that perception is affected by semantic knowledge, specifically that achromatic bananas look yellow.  However, bananas are domesticated (Heslop-Harrison & Schwarzacher, 2007).  The link between a banana’s structure and colour, therefore, is a constructed niche – cultivators fertilise the ‘best’ bananas, which go on to influence the way they perceive bananas, which affects which bananas they fertilise, and so on.  This means that the effect found in Hansen et al. cannot be innate, since the colour and structure of a banana have changed (see below).  Modulating perception with flexible, high-level categories is a way of keeping up with rapidly changing environments.

Differing structures and colours of six species of banana, all ripe. Top left: Musa balbisiana, ancestor of modern cultivated bananas. Top right: Pink Banana (Musa velutina). Bottom, from left to right: Plantains (Musa paradisiacal), red bananas (Musa rutilus), Bananito (Musa acuminate) and Cavendish bananas (Musa cavendishii). Images from Wikimedia Commons, http://commons.wikimedia.org

Less anecdotally, Griffin’s (2006) model, which classified objects using colour (see section 5.2.2), found that natural colour categories optimally aid the identification of objects.  Furthermore, the model performed equally well for natural and manufactured objects.  That is, manufactured objects have been coloured to be maximally classifiable by colour, according to linguistic colour categorisations.  This would be an intuitive and efficient tactic if, as Embodied Cognition suggests, comprehension is scaffolded onto systems of object recognition (MacWhinney, 1999).  There would be no advantage in doing this in a Symbolist system where perceptions and concepts have arbitrary connections.

Next, why universal patterns are not evidence for innate constraints ->

Laland, K., Odling-Smee, J., & Feldman, M. (2000). Niche construction, biological evolution, and cultural change Behavioral and Brain Sciences, 23 (1), 131-146 DOI: 10.1017/S0140525X00002417

Hansen, T., Olkkonen, M., Walter, S., & Gegenfurtner, K. (2006). Memory modulates color appearance Nature Neuroscience, 9 (11), 1367-1368 DOI: 10.1038/nn1794

Heslop-Harrison, J., & Schwarzacher, T. (2007). Domestication, Genomics and the Future for Banana Annals of Botany, 100 (5), 1073-1084 DOI: 10.1093/aob/mcm191

Griffin, L. (2004). Optimality of the Basic Colours Categories Journal of Vision, 4 (8), 309-309 DOI: 10.1167/4.8.309

Specific Language Impairment, Autism and Language Evolution

My last post speculated about what some conditions which manifest impaired theory of mind could tell us about the evolution of ToM. Of these conditions autism was one which could be the most informative when it comes to looking at the genetics of how ToM evolved, in this post I will look at what autism could tell us, not only about theory of mind, but also about other aspects of the language faculty.

Dorothy Bishop has recently written a paper exploring the above average co-occurrence of Specific Language Impariment (SLI) and Autistic Spectrum Disorders (ASD).

SLI is a condition where a child fails to develop spoken language on the normal schedule, for no observable or obvious reason (Bishop and Norbury 2008). Whilst ASD and SLI are regarded as distinct conditions, these disorders co-occur at above chance levels.

Bishop (2010) explores why this might be. Bishop begins her paper by painting a textbook example of a child with SLI. This example is of a child with normal social interaction and nonverbal communication, but with specific difficulties in mastering structural aspects of language, especially syntax and phonological skills. So this typical picture is not one of an autistic child in that one of the defining features of autism is a limited capacity for normal social interaction and a child is much more likely to be deficient in pragmatic skills than syntactic or phonological skills.

Bishop states that despite the fact that according to conventional diagnostic frameworks, SLI andASD are mutually exclusive diagnoses, similarities exist between the two conditions and these include:

  • They are both highly heritable
  • Identical, monozygotic twins are significantly more concordant than fraternal, dizygotic twins for autism and SLI
  • In both conditions rates of impairment in first degree relatives are higher than in the general population
  • First degree relatives of affected individuals of both conditions often manifest sub-threshold symptoms
  • These conditions correspond to points on a continuum of impairment, rather than all-or-none diseases

So any model of causation for either condition must take into account the following considerations:

  • Above chance levels of comorbidity between SLI and ASD
  • Rates of language impairment in relatives of probands with SLI and ASD
  • Molecular genetic findings of shared genetic risk factors for ASD and SLI

Now the article goes on to explore etiological models which explain these considerations with varying degrees of success. I’m not going to pretend to understand these models as I have only ever been formally taught in linguistics and so I’m a bit stumped by genetic psychology. If you’re much smarter than me you can read the article yourself here:

http://www.springerlink.com/content/gg087q4h51j5127g/fulltext.pdf

So what I got from this article was that the genetic factors involved in autism can not only cause the characteristics typical of a person with autism (pragmatic impairments) but also other language impairments which are typical of a person with a Specific Language Impairment. Specifically the CNTNAP2 gene has been found in independent samples to be associated with both ASD and SLI. This is interesting because it could show that gene mutations which cause improved social abilities could have also caused changes in our linguistic ability on a syntactic or phonological level.

Disclaimer: Sorry if I’ve made too many assumptions in the conclusion I’ve just drawn. As I said above I know next to nothing about genetic psychology but I just felt this research would have interesting consequences in the field of language evolution. I’d love to hear the thoughts of people who know better than I do.

References

Bishop, DVM. (2010) Overlaps Between Autism and Language Impairment:
Phenomimicry or Shared Etiology? Behavior Genetics 40:5, 618-629

Bishop DVM, Norbury CF (2008) Speech and language disorders. In: Rutter M, Bishop DVM, Pine D, Scott S, Stevenson J, Taylor E, Thapar A (eds) Rutter’s child

Evolution of Colour Terms: 7 Perceptual Warping

The last few posts have showed that several domains of constraint influence colour categorisation. There is evidence that these categorisations can influence perception, which has been identified as a crucial argument for Relativism. This section considers the Cultural implication, summarised in the last section, in greater depth. First, the idea of perceptual warping is explained and applied to colour categorisation. Next, the impact of a feedback loop caused by an Embodied approach is discussed in terms of Niche Construction. Thirdly, perceptual warping, within a system with Niche Construction dynamics is argued to lead to convergence of perceptual spaces, resulting in better communication. Finally, a note is made on compositionality in language. It is concluded that Embodied Cognition may explain some of the features of the emergence of language.

Perceptual Spaces

This section explains perceptual warping. Many models of the cultural transmission of denotation systems begin by defining a perceptual space for each individual which is then divided up with loci and boundaries (e.g., deBoer, 1999). Eventually, a kind of ‘lookup table’ is produced where an individual calculates within which boundary a given stimulus falls in order to classify it. An alternate view would be that each individual alters (warps) the perceptual space to suit the categories (Goldstone, 1994; Kuhl, 1994). This is not a controversial theory for the auditory modality. For instance, although born with the ability to detect any meaningful difference in any language, children eventually become unable to detect those differences that do not exist in the languages spoken around them (Eimas, 1978, Miyawaki, 1975, Kuhl, 1983). In other words, humans do not merely categorise areas of the audible spectrum as belonging to particular phonemes, but actually alter their perceptual space to suit the phonemic system. In the visual domain, Kuhl (1994) argues that the perceptual space is permanently changed by exposure to graphemes, although Lupyan (2008) shows that categorical perception can emerge on-line.

The figure above is a graphical illustration of warping a perceptual space (Colour space of Culina, from Regier, Kay & Khertarpal, 2007, p. 1439). The division of the Munsell colour space by speakers of Culina is warped and rotated to optimally encode the colour categories. Formally, the parameterisations are the same. However, warping the perceptual space allows for compression of information. For example, the initial encoding of the Figure takes up to 40 x 8 units, while the final encoding takes only 4 units . This can ease processing and storage requirements. Compression reduces the uncertainty between categories (e.g., red vs. green) and the ability for individuals to differentiate within categories (e.g., different shades of red), similar to the effects of categorical perception.

This approach has already been suggested. Buchsbaum and Bloch’s (2002) study showed that the NMF algorithm approximates colour categorisation in real languages (Non-negative Matrix Factorisation – a factor analysis algorithm like PCA, except that it is designed for values that are inherently positive and cannot be centred). NMF essentially warps the perceptual space to best describe its limits. The current study suggests that language sets constraints on an NMF-like process which works to alter the perceptual space to suit culturally salient colour contrasts. However, it is suggested that this optimisation is not primarily a response to an adaptive pressure, but a consequence of the way we understand language. Indeed, it is only because our perceptions can be aligned with our language system that semantics works at all. This would fit better with an Embodied view than a Symbolist view.

However, humans are able to perceive gradients in colours within categories.  There are two explanations for this.  Firstly, there may be two separate, competing perceptual and ‘categorical’ colour spaces, similar to Connell and Lynott’s (2009) hypothesis.  Since the categorical system is shared and can quickly adapt to immediate environmental pressures, one would expect agents with two systems to increasingly rely on the categorical system, especially for communication (see code duality theory, e.g., Hoffmeyer & Emmeche, 1991).  In contrast, novel tasks which involved no communication (e.g., comparing colours and choosing an ‘odd one out’) may rely more on the true perceptual system.  A second explanation for the flexibility of categories is suggested by Lupyan (2008) who shows that perceptual spaces can be warped, but by context-specific, online processes rather than long-term, memory-based processes.  This would allow a single conceptual/perceptual system (as Embodied Cognition hypothesises), as well as explaining the plasticity of language.

Next, a look at how Embodied Cognition fits into this picture ->

DEBOER, B. (2000). Self-organization in vowel systems Journal of Phonetics, 28 (4), 441-465 DOI: 10.1006/jpho.2000.0125

Goldstone, R. (1994). Influences of categorization on perceptual discrimination. Journal of Experimental Psychology: General, 123 (2), 178-200 DOI: 10.1037//0096-3445.123.2.178

Kuhl, P. (1994). Learning and representation in speech and language Current Opinion in Neurobiology, 4 (6), 812-822 DOI: 10.1016/0959-4388(94)90128-7

Miyawaki, K., Strange, W., Verbrugge, R. R., Liberman, A. M., Jenkins, J. J., & Fujimura, O. (1975). An effect of linguistic experience: The discrimination of (r) and (l) by native speakers of Japanese and
English
Perception and Psychophysics, 18, 331-340

KUHL, P. (1983). Perception of auditory equivalence classes for speech in early infancy Infant Behavior and Development, 6 (2-3), 263-285 DOI: 10.1016/S0163-6383(83)80036-8

Lupyan G (2008). From chair to “chair”: a representational shift account of object labeling effects on memory. Journal of experimental psychology. General, 137 (2), 348-69 PMID: 18473663

Buchsbaum, G. (2002). Color categories revealed by non-negative matrix factorization of Munsell color spectra Vision Research, 42 (5), 559-563 DOI: 10.1016/S0042-6989(01)00303-0

Connell, L., & Lynott, D. (2009). Is a bear white in the woods? Parallel representation of implied object color during language comprehension Psychonomic Bulletin & Review, 16 (3), 573-577 DOI: 10.3758/PBR.16.3.573

Theory of Mind and Language Evolution; What can psychopathology tell us?

Theory of Mind is the ability to infer other persons’ mental states and emotions. It is thought to have evolved as part of the human’s social brain and probably emerged as an adaptive response to increasingly complex primate social interaction.

Brüne and Brüne-Cohrs (2006) explore the ‘evolutionary cost’ of language evolution:

This sophisticated ‘metacognitive’ ability comes at an evolutionary cost, reflected in a broad spectrum of psychopathological conditions. Extensive research into autistic spectrum disorders has revealed that theory of mind may be selectively impaired, leaving other cognitive faculties intact. Recent studies have shown that observed deficits in theory of mind task performance are part of a broad range of symptoms in schizophrenia, bipolar affective disorder, some forms of dementia, ‘psychopathy’ and in other psychiatric disorders.

Now it’s fairly uncontroversial to assert that without the ability of theory of mind humans would have never evolved language (Sperber and Wilson, 2002). This is due to the fact that if one can’t attribute another to have a ‘mind’ like ones own, or assume that other minds hold different information to ones own then one would see little point in trying to share information. (I’m sorry for the amount of ‘ones’ in that sentence).

Sooo, it does not seem presumptuous to assume that people interested in the evolution of language should be interested in theory of mind, in fact for many years evolutionary linguists, psychologists and biologists have been looking into this, but mostly through observing the behaviour of animals, and especially primates to see if they display theory of mind capabilities. A good summary of this work can be found here, and a lot of relevant studies can be found on this blog in the What makes humans unique? posts by Michael. I’m not going to look at the animal data in this post, but instead what the deficiencies in some human conditions can tell us about the evolution of theory of mind. That is, what can autism, schizophrenia, bipolar affective disorder, dementia, ‘psychopathy’ and other psychiatric disorders tell us?

Continue reading “Theory of Mind and Language Evolution; What can psychopathology tell us?”

Evolution of Colour Terms: 6 Categorisation Constraints

Continuing my series on the Evolution of Colour terms, this post reviews evidence for categorisation constraints on colour perception. For the full dissertation and for references, go here.

Continue reading “Evolution of Colour Terms: 6 Categorisation Constraints”

Evolution of Colour Terms: 5 Cultural Constraints

Continuing my series on the Evolution of Colour terms, this post reviews studies of cultural constraints on colour naming. For the full dissertation and for references, go here.

Continue reading “Evolution of Colour Terms: 5 Cultural Constraints”

Evolution of Colour Terms: 4 Learning Constraints

Continuing my series on the Evolution of Colour terms, this post reviews how learning constrains colour naming. For the full dissertation and for references, go here.

Continue reading “Evolution of Colour Terms: 4 Learning Constraints”