One philosophical theory about perception claims that perceiving is inferring the external world from the sensory signals. The argumentation goes as follows. Consider the retina: there is a spatially inhomogeneous set of photoreceptors; the image projected onto the retina is inverted, but you don’t see the world upside down; there are blood vessels that you [...]
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At first sight, it seems obvious what loudness is. A sound is loud when the acoustical wave carries a lot of energy. But if we think about it in details, we quickly encounter difficulties. One obvious thing is that if we play the same sound at different levels, then clearly the feeling of loudness directly [...] In sensory systems, one of the hardest computational problems is the “invariance problem”: the same perceptual category can be associated with a large diversity of sensory signals. A classical example is the problem of a recognizing a face: the same face can appear with different orientations relative to the observer, and under different lighting conditions, [...] In economy, free market theoreticians such as Milton Friedman have shown that under a number of assumptions, free markets are efficient. In particular, they do not have unemployment and resources are well distributed. This is based on conceptual arguments and a fair deal of mathematics, rather than on empirical evidence. The epistemology of economics is [...] In this post, I want to come back on a remark I made in a previous post, on the relationship between vision and spatial hearing. It appears that my account of the comparative study of Heffner and Heffner (Heffner & Heffner, 1992) was not accurate. Their findings are in fact even more interesting than I [...] In this blog, I have argued many times that if there are neural representations, these must be about relations. For example, a relation between two sensory signals, or about a potential action and the effect on the sensory signals. But what does it mean exactly that something (say neural activity) “represents” a relation? It turns [...] In a previous post, I pointed out that the word “information” is almost always used in neuroscience in the sense of information theory, and this is a very restricted notion of information that leads to dualism in many situations. There is another way to look at this issue, which is to ask the question: information [...] Rate vs. timing (XX) Flavors of spike-based theories (6) Predictive coding and spike-based inferenceIn two companion papers in Neural Computation (followed by a related paper on working memory), Sophie Denève developed a spike-based theory of Bayesian inference. It can be categorized as a representational spike-based theory, in the sense that spikes collectively represent some objective variable of the world, for which there is some uncertainty. It follows a [...] One phrase that occasionally pops up when speaking of the goal of computational neuroscience is “reverse engineering the brain”. This is quite an interesting phrase from an epistemological point of view. The analogy is to see the brain as an engineered device, the “engineer” being evolution, of which we do not possess the design plans. [...] Spike-based theories are sometimes discarded on the basis that spike timing is not reproducible in vivo, in response to the same stimulus. I already argued that, in addition to the fact that this is a controversial statement (because for example this could be due to a lack of control of independent variables such as attentional [...] |
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