perception – Replicated Typo

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

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.

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Evolving Linguistic Replicators: Major Transitions and Grammaticalisation

Just before Christmas I found myself in the pub speaking to Sean about his work on bilingualism, major transitions and the contrast between language change and the cultural evolution of language. Now, other than revealing that our social time is spent discussing our university work, the conversation brought up a distinction not often made: whilst language change is part of language evolution, the latter is also what we consider to be a major transition. As you evolutionary biologists will know, this concept is perhaps best examined and almost certainly popularised in Maynard Smith & Szathmáry’s (1995) The Major Transitions in Evolution. Here, the authors are not promoting the fallacy of guided evolution, where the inevitable consequence is increased and universal complexity. Their thesis is more subtle: that some lineages become more complex over time, with this increase being attributable to the way in which genetic information is transmitted between generations. In particular, they note eight transitions in the evolution of life:

What’s notable about these transitions, and why they aren’t necessarily an arbitrary list, is that all of them share some broad commonalities, namely:

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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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On Phylogenic Analogues

A recent post by Miko on Kirschner and Gerhart’s work on developmental constraints and the implications for evolutionary biology caught my eye due to the possible analogues which could be drawn with language in mind. It starts by saying that developmental constraints are the most intuitive out of all of the known constraints on phenotypic variation. Essentially, whatever evolves must evolve from the starting point, and it cannot ignore the features of the original. Thus, a winged horse would not occur, as six limbs would violate the basic bauplan of tetrapods. In the same way, a daughter language cannot evolve without taking into account the language it derives from and language universals. But instead of viewing this as a constraint which limits the massive variation we see biologically or linguistically between different phenotypes, developmental constraints can be seen as a catalyst for regular variation.

A pretty and random tree showing variation among IE languages.

Looking back over my courses, I’m surprised by how little I’ve noticed (different from how much was actually said) about reasons for linguistic variation. The modes of change are often noted: <th> is fronted in Fife, for instance, leading to the ‘Firsty Ferret’ instead of the ‘Thirsty Ferret’ as a brew, for instance. However, why the <th> is fronted at all isn’t explained beyond cursory hypothesis. But that’s a bit besides the point: what is the point is that phenotypic variation is not necessarily random, as there are constraints – due to the “buffering and canalizing of development” – which limit variation to a defined range of possibilities. There clearly aren’t any homologues between biological embryonic processes and linguistic constraints, but there are developmental analogues: the input bottleneck (paucity of data) given to children, learnability constraints, the necessity for communication, certain biological constraints to do with production and perception, etc. These all act on language to make variation occur only within certain channels, many of which would be predictable.

Another interesting point raised by the article is the robustness of living systems to mutation. The buffering effect of embryonic development results in the accumulation of ‘silent’ variation. This has been termed evolutionary capacitance. Silent variation can lay quiet, accumulating, not changing the phenotype noticeably until environmental or genetic conditions unmask them. I’ve seen little research (not that I don’t expect there to be plenty) on the theoretical implications of the influence of evolutionary capacitance on language change – in other words, how likely a language is to make small variations which don’t affect language understanding before a new language emerges (not that the term language isn’t arbitrary based on the speaking community, anyway). Are some languages more robust than others? Is robustness a quality which makes a language more likely to be used in multilingual settings – for instance, in New Guinea, if seven languages are mutually indistinguishable, is it likely the that local lingua franca is forced by its environment to be more robust in order to maximise comprehension?

The article goes on about the cost of robustness: stasis. This can be seen clearly in Late Latin, which was more robust than the daughter languages as it was needed to communicate in different environments where the language had branched off into the Romance languages, and an older form was necessary in order for communication to ensue. Thus, Latin retained usage well after the rest of it had evolved into other languages. Another example would be Homeric Greek, which retained many features lost in Attic, Doric, Koine, and other dialects, as it was used in only a certain environment and was therefore resistant to change. This has all been studied before better than I can sum it up here. But the point I am making is that analogues can be clearly drawn here, and some interesting theories regarding language become apparent only when seen in this light.

A good example, also covered, would be exploratory processes, as Kirschner and Gerhart call them. These are processes which allow for variation to occur in environments where other variables are forced to change. The example given is the growth of bone length, which requires corresponding muscular, circulatory, and other dependant systems to also change. The exploratory processes allow for future change to occur in the other systems. That is, they expedite plasticity. So, for instance, an ad hoc linguistic example would be the loss of a fixed word order, which would require that morphology step in to fill the gap. In such a case, particles or affixes or the like would have to have already paved the way for case markers to evolve, and would have had to have been present to some extent in the original word order system. (This may not be the best example, but I hope my point comes across.)

Naturally, much of this will have seemed intuitive. But, as Miko stated, these are useful concepts for thinking about evolution; and, in my own case especially, the basics ought to be brought back into scrutiny fairly frequently. Which is justification enough for this post. As always, comments appreciated and accepted. And a possible future post: clade selection as a nonsensical way to approach phylogenic variation.

References:

Caldwell, M. (2002). From fins to limbs to fins: Limb evolution in fossil marine reptiles American Journal of Medical Genetics, 112 (3), 236-249 DOI: 10.1002/ajmg.10773

Gerhart, J., & Kirschner, M. (2007). Colloquium Papers: The theory of facilitated variation Proceedings of the National Academy of Sciences, 104 (suppl_1), 8582-8589 DOI: 10.1073/pnas.0701035104

Is seeing believing?

I just finished watching the latest episode of Horizon, Is seeing believing? It had lots of cool material on recent research into our perceptual systems and how some unique individuals (see bat man and synaesthesia) are providing clues into the degree of plasticity our brain is capable of. I think this developmental flexibility has important implications for how we view the evolution of language, which certainly chimes with Deacon’s latest explanations. Another segment of the episode focused on a famous linguistic perceptual trick, known as the McGurk effect, demonstrating the interaction between hearing and vision in speech perception. Here is the first video I found on the subject (although I thought the Horizon episode provided a better visual explanation of it):

Never Too Old to Learn: FoxP2 Gene Has Important Post-developmental On-line Function

Experimental studies (e.g. Jones & Munhall 2000) indicate that humans monitor their own speech through hearing in order to maintain accurate vocal articulation throughout the lifespan. Similarly, songbirds not only rely on song input from tutors and conspecifics in the early stages of song development, but also on the ability to hear and detect production errors in their own song and adjust it accordingly with reference to an internal ‘sensory target’ following the initial song learning phase.

This phenomenon also extends to ‘closed-ended learners’ – birds who do not acquire novel song elements after an initial learning period, but who still demonstrate song variability in adulthood. Experimental studies have shown that in such species, vocal learning is more prolonged and fundamental to song production than originally thought. For example, Okanoya and Yamaguchi (1997) showed that afflicted deafening in adult Bengalese Finches resulted in the production of abnormal song syntax in a matter of days. This is parallel to the human condition whereby linguistic fidelity, particularly with regards to prosodic aspects such as pitch and intensity, gradually degrades in human adults with postlinguistically acquired auditory impairments.

Continue reading “Never Too Old to Learn: FoxP2 Gene Has Important Post-developmental On-line Function”

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

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