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The connectionist vehicle theory of phenomenal experience in the target article identifies consciousness with the brain’s explicit representation of information in the form of stable patterns of neural activity. Commentators raise concerns about both the conceptual and empirical adequacy of this proposal. On the former front they worry about our reliance on vehicles, on representation, on stable patterns of activity, and on our identity claim. On the latter front their concerns range from the general plausibility of a vehicle theory to our specific attempts to deal with the dissociation studies. We address these concerns, and then finish by considering whether the vehicle theory we have defended has a coherent story to tell about the active, unified subject to whom conscious experiences belong.

When cognitive scientists apply computational theory to the problem of phenomenal consciousness, as many of them have been doing recently, there are two fundamentally distinct approaches available. Either consciousness is to be explained in terms of the nature of the representational vehicles the brain deploys; or it is to be explained in terms of the computational processes defined over these vehicles. We call versions of these two approaches vehicle and process theories of consciousness, respectively. However, while there may be space for vehicle theories of consciousness in cognitive science, they are relatively rare. This is because of the influence exerted, on the one hand, by a large body of research which purports to show that the explicit representation of information in the brain and conscious experience are dissociable, and on the other, by the classical computational theory of mind – the theory that takes human cognition to be a species of symbol manipulation. But two recent developments in cognitive science combine to suggest that a reappraisal of this situation is in order. First, a number of theorists have recently been highly critical of the experimental methodologies employed in the dissociation studies – so critical, in fact, it’s no longer reasonable to assume that the dissociability of conscious experience and explicit representation has been adequately demonstrated. Second, classicism, as a theory of human cognition, is no longer as dominant in cognitive science as it once was. It now has a lively competitor in the form of connectionism; and connectionism, unlike classicism, does have the computational resources to support a robust vehicle theory of consciousness. In this paper we develop and defend this connectionist vehicle theory of consciousness. It takes the form of the following simple empirical hypothesis: phenomenal experience consists in the explicit representation of information in neurally realized PDP networks. This hypothesis leads us to re-assess some common wisdom about consciousness, but, we will argue, in fruitful and ultimately plausible ways.

One of the principal tasks Dennett sets himself in "Consciousness Explained" is to demolish the Cartesian theatre model of phenomenal consciousness, which in its contemporary garb takes the form of Cartesian materialism: the idea that conscious experience is a process of presentation realized in the physical materials of the brain. The now standard response to Dennett is that, in focusing on Cartesian materialism, he attacks an impossibly naive account of consciousness held by no one currently working in cognitive science or the philosophy of mind. Our response is quite different. We believe that, once properly formulated, Cartesian materialism is no straw man. Rather, it is an attractive hypothesis about the relationship between the computational architecture of the brain and phenomenal consciousness, and hence one that is worthy of further exploration. Consequently, our primary aim in this paper is to defend Cartesian materialism from Dennett's assault. We do this by showing that Dennett's argument against this position is founded on an implicit assumption (about the relationship between phenomenal experience and information coding in the brain), which while valid in the context of classical cognitive science, is not forced on connectionism.

In Connectionism and the Philosophy of Psychology, Horgan and Tienson (1996) argue that cognitive processes, pace classicism, are not governed by exceptionless, “representation-level” rules; they are instead the work of defeasible cognitive tendencies subserved by the non-linear dynamics of the brain’s neural networks. Many theorists are sympathetic with the dynamical characterisation of connectionism and the general (re)conception of cognition that it affords. But in all the excitement surrounding the connectionist revolution in cognitive science, it has largely gone unnoticed that connectionism adds to the traditional focus on computational processes, a new focus – one on the vehicles of mental representation, on the entities that carry content through the mind. Indeed, if Horgan and Tienson’s dynamical characterisation of connectionism is on the right track, then so intimate is the relationship between computational processes and representational vehicles, that connectionist cognitive science is committed to a resemblance theory of mental content.

This commentry focuses on the one major ecumenical theme propounded in Andy Clark's Being There that I find difficult to accept; this is Clark’s advocacy, especially in the third and final part of the book, of the extended nature of the embedded, embodied mind.

It is commonplace for both philosophers and cognitive scientists to express their allegiance to the "unity of consciousness". This is the claim that a subject’s phenomenal consciousness, at any one moment in time, is a single thing. This view has had a major influence on computational theories of consciousness. In particular, what we call single-track theories dominate the literature, theories which contend that our conscious experience is the result of a single consciousness-making process or mechanism in the brain. We argue that the orthodox view is quite wrong: phenomenal experience is not a unity, in the sense of being a single thing at each instant. It is a multiplicity, an aggregate of phenomenal elements, each of which is the product of a distinct consciousness-making mechanism in the brain. Consequently, cognitive science is in need of a multi-track theory of consciousness; a computational model that acknowledges both the manifold nature of experience, and its distributed neural basis.

When it comes to applying computational theory to the problem of phenomenal consciousness, cognitive scientists appear to face a dilemma. The only strategy that seems to be available is one that explains consciousness in terms of special kinds of computational processes. But such theories, while they dominate the field, have counter-intuitive consequences; in particular, they force one to accept that phenomenal experience is composed of information processing effects. For cognitive scientists, therefore, it seems to come down to a choice between a counter-intuitive theory or no theory at all. We offer a way out of this dilemma. We argue that the computational theory of mind doesn't force cognitive scientists to explain consciousness in terms of computational processes, as there is an alternative strategy available: one that focuses on the representational vehicles that encode information in the brain. This alternative approach to consciousness allows us to do justice to the standard intuitions about phenomenal experience, yet remain within the confines of cognitive science.

AbstractCarrots are main dietary sources of several potential anti-cancer compounds, including polyacetylenes, while β-carotene has shown no benefits in controlled cancer trials. Accordingly, associations between carrot intake and cancer incidence were quantified, where necessary using α-carotene as a non-causal biomarker of carrot consumption, by searching for studies published before June 2022 reporting risk estimates for relationships of cancer incidence with carrot intake or α-carotene intake or α-carotene plasma concentration, supplemented with hand searches of included studies and reviews. Meta-analyses comparing highest and lowest reported intakes in prospective studies using a random-effects model estimated summary relative risks (RRs) with 95% confidence intervals (CIs), separately for carrot intake or α-carotene plasma concentration, and the corresponding dose-responses. Of 198 observational studies, in 50 prospective studies with 52000 cases recording carrot intake, the cancer-risk was substantially reduced (RR 0.90, 95% CI 0.87–0.94, p ˂ 0·00004). In 30 prospective studies with 9331 cases reporting plasma α-carotene levels, summary RR was 0.80 (0.72–0.89, p ˂ 0·00006). For both exposure types, inter-study heterogeneity was moderate, interaction with cancer types insignificant, and the dose-response significant (p ˂ 0·01). In conclusion, carrot consumption is robustly associated with decreased cancer-risk; carrot consumption should be encouraged, and the causal mechanisms further investigated. [ABSTRACT FROM AUTHOR]

Summary: A random sample of fresh cassava roots and cassava products, purchased at various retail outlets in Singapore during 2016–2017, had total cyanogenic potential (CNp–expressed as mean ± standard deviation, mg kg−1 HCN, fresh weight basis) as follows: fresh roots (n = 66) from three SE Asian countries, 59.0 ± 19.2; peeled chilled root pieces from Malaysia (20 × 1‐kg packs), 38.5 ± 16.5; cassava flour from Indonesia (8 × 1‐kg packs), 11.7 ± 8.2; dried Indonesian chips for home frying (5 × 250 g packs), 61.6 ± 16.5; one pack (120 g) of Malaysian ready‐to‐eat (RTE) chips, 17.1 ± 3.2. CNp in all flour and RTE chips was below 20 mg kg−1. The majority of fresh roots (59.1%) and packs of dried chips (80%), and 15% of packs of peeled chilled root parenchyma, exceeded the Codex Alimentarius limit (50 mg kg−1) for 'sweet' (boil‐and‐eat) cassava. [ABSTRACT FROM AUTHOR]

Martinez-Manrique contends that we overlook a possible nonconnectionist vehicle theory of consciousness. We argue that the position he develops is better understood as a hybrid vehicle/process theory. We assess this theory and in doing so clarify the commitments of both vehicle and process theories of consciousness.