One of the things that Deutscher wrote in his article was that:
“The area where the most striking evidence for the influence of language on thought has come to light is the language of space — how we describe the orientation of the world around us.”
As I’ve written a bit about this topic on my other blog, Shared Symbolic Storage, I’ll repost a short series of posts over the next couple of days.
As Deutscher said, this is a very fascinating avenue of linguistic research that gives much insight into the nature of language and cognition as well as their relationship. In addition, it also presents us with new facts and considerations we have to take into account when we think about how language and cognition evolved.
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
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.
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
