Turtles All the Way Down: How Dennett Thinks

An Essay in Cognitive Rhetoric

I want to step back from the main thread of discussion and look at something else: the discussion itself. Or, at any rate, at Dennett’s side of the argument. I’m interested in how he thinks and, by extension, in how conventional meme theorists think.

And so we must ask: Just how does thinking work, anyhow? What is the language of thought? Complicated matters indeed. For better or worse, I’m going to have to make it quick and dirty.

Embodied Cognition

In one approach the mind’s basic idiom is some form of logical calculus, so-called mentalese. While some aspects of thought may be like that, I do not think it is basic. I favor a view called embodied cognition:

Cognition is embodied when it is deeply dependent upon features of the physical body of an agent, that is, when aspects of the agent’s body beyond the brain play a significant causal or physically constitutive role in cognitive processing.

In general, dominant views in the philosophy of mind and cognitive science have considered the body as peripheral to understanding the nature of mind and cognition. Proponents of embodied cognitive science view this as a serious mistake. Sometimes the nature of the dependence of cognition on the body is quite unexpected, and suggests new ways of conceptualizing and exploring the mechanics of cognitive processing.

One aspect of cognition is that we think in image schemas, simple prelinguistic structures of experience. One such image schema is that of a container: Things can be in a container, or outside a container; something can move from one container to another; it is even possible for one container to contain another.

Memes in Containers

The container scheme seems fundamental to Dennett’s thought about cultural evolution. He sees memes as little things that are contained in a larger thing, the brain; and these little things, these memes, move from one brain to another.

This much is evident on the most superficial reading of what he says, e.g. “such classic memes as songs, poems and recipes depended on their winning the competition for residence in human brains” (from New Replicators, The). While the notion of residence may be somewhat metaphorical, the locating of memes IN brains is not; it is literal.

What I’m suggesting is that this containment is more than just a contingent fact about memes. That would suggest that Dennett has, on the one hand, arrived at some concept of memes and, on the other hand, observed that those memes just happen to exist in brains. Yes, somewhere Over There we have this notion of memes as the genetic element of culture; that’s what memes do. But Dennett didn’t first examine cultural process to see how they work. As I will argue below, like Dawkins he adopted the notion by analogy with biology and, along with it, the physical relationship between genes and organisms. The container schema is thus foundational to the meme concept and dictates Dennett’s treatment of examples.

The rather different conception of memes that I have been arguing in these notes is simply unthinkable in those terms. If memes are (culturally active) properties of objects and processes in the external world, then they simply cannot be contained in brains. A thought process based on the container schema cannot deal with memes as I have been conceiving them. Continue reading “Turtles All the Way Down: How Dennett Thinks”

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: 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: 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
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