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: 8 Embodied Relationships

In a series of  posts, I’ve been discussing constraints on the evolution of colour terms.  In the last post, I discussed Perceptual Warping.  Here, a further adjustment to the assumptions about perceptual space is suggested.

The assumption that all perceptual spaces are the same may be unrealistic and may favour Universalism (see Levinson, 2000).  To begin with, colour vision and colour concepts develop during ontogeny (Bornstein, Kessen & Weiskopf, 1976, Roberson, Davidoff, Davies & Shapiro, 2004).  Secondly, there may be an underestimation of the variation in colour term systems across cultures (see section 5.2.5).  Going back to the example of Tzotzil, colour terms seem to be intricately related in a way that, for example, ‘blue’ and ‘green’ in English seem not to be.  This prompts a third way of approaching the formation of colour categories.  An individual begins with no conceptual space, but learns relationships between colour terms and perceptions.  For example, learning that ‘yellow’ and ‘blue’ are as different as light with 640nm and 450nm wavelengths.  By using an embodied, relational approach to colour categories, one can construct relationships between terms based on any perceivable feature.  This could include brilliance, reflectance or the physical structure of the object.  Therefore, a banana looks yellow because its colour is understood in terms of its structure, as well as its spectral properties.  This is a more stable approach to object identification, since structures are usually stable, while colour is not.  It would also fit with the grammaticalisation of colour terms to extend to other domains.  For example, the Tzotzil sak-vilan, meaning ‘pastel’ originates from the fading of colours on fabric from fraying (MacKeigan & Muth, 2006).  Constructing relationships between words based on the relationships between the perceptual properties of their referents would then be part of a general learning mechanism which facilitated the learning of all concepts.

Next, how Embodied Cognition allows a Niche-Construction Dynamic ->

Levinson, S. (2000). Yeli Dnye and the Theory of Basic Color Terms Journal of Linguistic Anthropology, 10 (1), 3-55 DOI: 10.1525/jlin.2000.10.1.3

Bornstein, M., Kessen, W., & Weiskopf, S. (1976). Color vision and hue categorization in young human infants. Journal of Experimental Psychology: Human Perception and Performance, 2 (1), 115-129 DOI: 10.1037/0096-1523.2.1.115

Roberson, D., Davidoff, J., Davies, I., & Shapiro, L. (2004). The Development of Color Categories in Two Languages: A Longitudinal Study. Journal of Experimental Psychology: General, 133 (4), 554-571 DOI: 10.1037/0096-3445.133.4.554

Evolution of Colour Terms: 3 Perceptual Constraints

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

Continue reading “Evolution of Colour Terms: 3 Perceptual Constraints”

Evolution of Colour Terms: Part 1

In a series of posts, I’ll review the current state of the field of the Evolution of Colour Categories.  It has been argued that universals in colour naming across cultures can be traced back to constraints from many domains including genetic, perceptual and environmental.    I’ll review these arguments and show that if our perception is affected by our language, then many conflicts can be resolved.  Furthermore, it undermines the Universalist assumption that universal patterns in colour terms are evidence for innate constraints.

Part 1: Domains of Constraint

Genetic Constraints

Environmental Constraints

Perceptual Constraints

Learning Constraints

Cultural Constraints

Categorisation Constraints

Part 2: Universal patterns are not evidence for innate constraints

Perceptual Warping

Embodied Relationships

Niche Construction

Universal Patterns are not Evidence for Innate Constraints

For the full dissertation and for references, go here.

Continue reading “Evolution of Colour Terms: Part 1”