Category: Cognitive Science

Deep Simulation in the Southern Hemisphere

Mark DavisLeave a comment

I’m unusually behind in my postings due to travel. I’ve been prepping for and now deep inside a fresh pass through New Zealand after two years away. The complexity of the place seems to have a certain draw for me that has lured me back, yet again, to backcountry tramping amongst the volcanoes and glaciers, and to leasurely beachfront restaurants painted with eruptions of summer flowers fueled by the regular rains.

I recently wrote a technical proposal that rounded up a number of the most recent advances in deep learning neural networks. In each case, like with Google’s transformer architecture, there is a modest enhancement that is based on a realization of a deficit in the performance of one of two broad types of networks, recurrent and convolutional.

An old question is whether we learn anything about human cognition if we just simulate it using some kind of automatically learning mechanism. That is, if we use a model acquired through some kind of supervised or unsupervised learning, can we say we know anything about the original mind and its processes?

We can at least say that the learning methodology appears to be capable of achieving the technical result we were looking for. But it also might mean something a bit different: that there is not much more interesting going on in the original mind. In this radical corner sits the idea that cognitive processes in people are tactical responses left over from early human evolution. All you can learn from them is that they may be biased and tilted towards that early human condition, but beyond that things just are the way they turned out.

If we take this position, then, we might have to discard certain aspects of the social sciences.… Read the rest

Ambiguously Slobbering Dogs

Mark DavisLeave a comment

I was initially dismissive of this note from Google Research on improving machine translation via Deep Learning Networks by adding in a sentence-level network. My goodness, they’ve rediscovered anaphora and co-reference resolution! Next thing they will try is some kind of network-based slot-filler ontology to carry gender metadata. But their goal was to add a framework to their existing recurrent neural network architecture that would support a weak, sentence-level resolution of translational ambiguities while still allowing the TPU/GPU accelerators they have created to function efficiently. It’s a hack, but one that potentially solves yet another corner of the translation problem and might result in a few percent further improvements in the quality of the translation.

But consider the following sentences:

The dog had the ball. It was covered with slobber.

The dog had the ball. It was thinking about lunch while it played.

In these cases, the anaphora gets resolved by semantics and the resolution seems largely an automatic and subconscious process to us as native speakers. If we had to translate these into a second language, however, we would be able to articulate that there are specific reasons for correctly assigning the “It” to the ball in the first two sentences. Well, it might be possible for the dog to be covered with slobber, but we would guess the sentence writer would intentionally avoid that ambiguity. The second set of sentences could conceivably be ambiguous if, in the broader context, the ball was some intelligent entity controlling the dog. Still, when our guesses are limited to the sentence pairs in isolation we would assign the obvious interpretations. Moreover, we can resolve giant, honking passage-level ambiguities with ease, where the author is showing off in not resolving the co-referents until obscenely late in the text.… Read the rest

Brain Gibberish with a Convincing Heart

Mark DavisLeave a comment

Elon Musk believes that direct brain interfaces will help people better transmit ideas to one another in addition to just allowing thought-to-text generation. But there is a fundamental problem with this idea. Let’s take Hubert Dreyfus’ conception of the way meaning works as being tied to a more holistic view of our social interactions with others. Hilary Putnam would probably agree with this perspective, though now I am speaking for two dead philosphers of mind. We can certainly conclude that my mental states when thinking about the statement “snow is white” are, borrowing from Putnam who borrows from Quine, different from a German person thinking “Schnee ist weiß.” The orthography, grammar, and pronunciation are different to begin with. Then there is what seems to transpire when I think about that statement: mild visualizations of white snow-laden rocks above a small stream for instance, or, just now, Joni Mitchell’s “As snow gathers like bolts of lace/Waltzing on a ballroom girl.” The centrality or some kind of logical ground that merely asserts that such a statement is a propositional truth that is shared in some kind of mind interlingua doesn’t bear much fruit to the complexities of what such a statement entails.

Religious and political terminology is notoriously elastic. Indeed, for the former, it hardly even seems coherent to talk about the concept of supernatural things or events. If they are detectable by any other sense than some kind of unverifiable gnosis, then they are at least natural in that they are manifesting in the observable world. So supernatural imposes a barrier that seems to preclude any kind of discussion using ordinary language. The only thing left is a collection of metaphysical assumptions that, in lacking any sort of reference, must merely conform to the patterns of synonymy, metonymy, and other language games that we ordinarily reserve for discernible events and things.… Read the rest

The Obsessive Dreyfus-Hawking Conundrum

Mark DavisLeave a comment

I’ve been obsessed lately. I was up at 5 A.M. yesterday and drove to Ruidoso to do some hiking (trails T93 to T92, if interested). The San Augustin Pass was desolate as the sun began breaking over, so I inched up into triple digit speeds in the M6. Because that is what the machine is made for. Booming across White Sands Missile Range, I recalled watching base police work with National Park Rangers to chase oryx down the highway while early F117s practiced touch-and-gos at Holloman in the background, and then driving my carpool truck out to the high energy laser site or desert ship to deliver documents.

I settled into Starbucks an hour and a half later and started writing on ¡Reconquista!, cranking out thousands of words before trying to track down the trailhead and starting on my hike. (I would have run the thing but wanted to go to lunch later and didn’t have access to a shower. Neither restaurant nor diners deserve an après-run moi.) And then I was on the trail and I kept stopping and taking plot and dialogue notes, revisiting little vignettes and annotating enhancements that I would later salt in to the main text over lunch. And I kept rummaging through the development of characters, refining and sifting the facts of their lives through different sets of sieves until they took on both a greater valence within the story arc and, often, more comedic value.

I was obsessed and remain so. It is a joyous thing to be in this state, comparable only to working on large-scale software systems when the hours melt away and meals slip as one cranks through problem after problem, building and modulating the subsystems until the units begin to sing together like a chorus.… Read the rest

Tweak, Memory

Mark DavisLeave a comment

Artificial Neural Networks (ANNs) were, from early on in their formulation as Threshold Logic Units (TLUs) or Perceptrons, mostly focused on non-sequential decision-making tasks. With the invention of back-propagation training methods, the application to static presentations of data became somewhat fixed as a methodology. During the 90s Support Vector Machines became the rage and then Random Forests and other ensemble approaches held significant mindshare. ANNs receded into the distance as a quaint, historical approach that was fairly computationally expensive and opaque when compared to the other methods.

But Deep Learning has brought the ANN back through a combination of improvements, both minor and major. The most important enhancements include pre-training of the networks as auto-encoders prior to pursuing error-based training using back-propagation or  Contrastive Divergence with Gibbs Sampling. The critical other enhancement derives from Schmidhuber and others work in the 90s on managing temporal presentations to ANNs so the can effectively process sequences of signals. This latter development is critical for processing speech, written language, grammar, changes in video state, etc. Back-propagation without some form of recurrent network structure or memory management washes out the error signal that is needed for adjusting the weights of the networks. And it should be noted that increased compute fire-power using GPUs and custom chips has accelerated training performance enough that experimental cycles are within the range of doable.

Note that these are what might be called “computer science” issues rather than “brain science” issues. Researchers are drawing rough analogies between some observed properties of real neuronal systems (neurons fire and connect together) but then are pursuing a more abstract question as to how a very simple computational model of such neural networks can learn.… Read the rest

Apprendre à traduire

Mark DavisLeave a comment

Google’s translate has always been a useful tool for awkward gists of short texts. The method used was based on building a phrase-based statistical translation model. To do this, you gather up “parallel” texts that are existing, human, translations. You then “align” them by trying to find the most likely corresponding phrases in each sentence or sets of sentences. Often, between languages, fewer or more sentences will be used to express the same ideas. Once you have that collection of phrasal translation candidates, you can guess the most likely translation of a new sentence by looking up the sequence of likely phrase groups that correspond to that sentence. IBM was the progenitor of this approach in the late 1980’s.

It’s simple and elegant, but it always was criticized for telling us very little about language. Other methods that use techniques like interlingual transfer and parsers showed a more linguist-friendly face. In these methods, the source language is parsed into a parse tree and then that parse tree is converted into a generic representation of the meaning of the sentence. Next a generator uses that representation to create a surface form rendering in the target language. The interlingua must be like the deep meaning of linguistic theories, though the computer science versions of it tended to look a lot like ontological representations with fixed meanings. Flexibility was never the strong suit of these approaches, but their flaws were much deeper than just that.

For one, nobody was able to build a robust parser for any particular language. Next, the ontology was never vast enough to accommodate the rich productivity of real human language. Generators, being the inverse of the parser, remained only toy projects in the computational linguistic community.… Read the rest

Boredom and Being a Decider

Mark DavisLeave a comment

tds_decider2_v6Seth Lloyd and I have rarely converged (read: absolutely never) on a realization, but his remarkable 2013 paper on free will and halting problems does, in fact, converge on a paper I wrote around 1986 for an undergraduate Philosophy of Language course. I was, at the time, very taken by Gödel, Escher, Bach: An Eternal Golden Braid, Douglas Hofstadter’s poetic excursion around the topic of recursion, vertical structure in ricercars, and various other topics that stormed about in his book. For me, when combined with other musings on halting problems, it led to a conclusion that the halting problem could be probabilistically solved by an observer who decides when the recursion is too repetitive or too deep. Thus, it prescribes an overlay algorithm that guesses about the odds of another algorithm when subjected to a time or resource constraint. Thus we have a boredom algorithm.

I thought this was rather brilliant at the time and I ended up having a one-on-one with my prof who scoffed at GEB as a “serious” philosophical work. I had thought it was all psychedelically transcendent and had no deep understanding of more serious philosophical work beyond the papers by Kripke, Quine, and Davidson that we had been tasked to read. So I plead undergraduateness. Nevertheless, he had invited me to a one-on-one and we clashed over the concept of teleology and directedness in evolutionary theory. How we got to that from the original decision trees of halting or non-halting algorithms I don’t recall.

But now we have an argument that essentially recapitulates that original form, though with the help of the Hartmanis-Stearns theorem to support it. Whatever the algorithm that runs in our heads, it needs to simulate possible outcomes and try to determine what the best course of action might be (or the worst course, or just some preference).… Read the rest

Desire and Other Matters

Mark DavisLeave a comment

“What matters?” is a surprisingly interesting question. I think about it constantly since it weighs-in whenever plotting future choices, though often I seem to be more autopilot than consequentialist in these conceptions. It is an essential first consideration when trying to value one option versus another. I can narrow the question a bit to “what ideas matter?” This immediately externalizes the broad reality of actions that meaningfully improve lives, like helping others, but still leaves a solid core of concepts that are valued more abstractly. Does the traditional Western liberal tradition really matter? Do social theories? Are less intellectually-embellished virtues like consistency and trust more relevant and applicable than notions like, well, consequentialism?

Maybe it amounts to how to value certain intellectual systems against others?

Some are obviously more true than others. So “dowsing belief systems” are less effective in a certain sense than “planetary science belief systems.” Yet there are a broader range of issues at work.

But there are some areas of the liberal arts that have a vexing relationship with the modern mind. Take linguistics. The field ranges from catalogers of disappearing languages to theorists concerned with how to structure syntactic trees. Among the latter are the linguists who have followed Noam Chomsky’s paradigm that explains language using a hierarchy of formal syntactic systems, all of which feature recursion as a central feature. What is interesting is that there have been very few impacts of this theory. It is very simple at its surface: languages are all alike and involve phrasal groups that embed in deep hierarchies. The specific ways in which the phrases and their relative embeddings take place may differ among languages, but they are alike in this abstract way.… Read the rest

Motivation, Boredom, and Problem Solving

Mark DavisLeave a comment

shatteredIn the New York Times Stone column, James Blachowicz of Loyola challenges the assumption that the scientific method is uniquely distinguishable from other ways of thinking and problem solving we regularly employ. In his example, he lays out how writing poetry involves some kind of alignment of words that conform to the requirements of the poem. Whether actively aware of the process or not, the poet is solving constraint satisfaction problems concerning formal requirements like meter and structure, linguistic problems like parts-of-speech and grammar, semantic problems concerning meaning, and pragmatic problems like referential extension and symbolism. Scientists do the same kinds of things in fitting a theory to data. And, in Blachowicz’s analysis, there is no special distinction between scientific method and other creative methods like the composition of poetry.

We can easily see how this extends to ideas like musical composition and, indeed, extends with even more constraints that range from formal through to possibly the neuropsychology of sound. I say “possibly” because there remains uncertainty on how much nurture versus nature is involved in the brain’s reaction to sounds and music.

In terms of a computational model of this creative process, if we presume that there is an objective function that governs possible fits to the given problem constraints, then we can clearly optimize towards a maximum fit. For many of the constraints there are, however, discrete parameterizations (which part of speech? which word?) that are not like curve fitting to scientific data. In fairness, discrete parameters occur there, too, especially in meta-analyses of broad theoretical possibilities (Quantum loop gravity vs. string theory? What will we tell the children?) The discrete parameterizations blow up the search space with their combinatorics, demonstrating on the one hand why we are so damned amazing, and on the other hand why a controlled randomization method like evolutionary epistemology’s blind search and selective retention gives us potential traction in the face of this curse of dimensionality.… Read the rest

Local Minima and Coatimundi

Mark Davis1 Comment

CoatimundiEven given the basic conundrum of how deep learning neural networks might cope with temporal presentations or linear sequences, there is another oddity to deep learning that only seems obvious in hindsight. One of the main enhancements to traditional artificial neural networks is a phase of supervised pre-training that forces each layer to try to create a generative model of the input pattern. The deep learning networks then learn a discriminant model after the initial pre-training is done, focusing on the error relative to classification versus simply recognizing the phrase or image per se.

Why this makes a difference has been the subject of some investigation. In general, there is an interplay between the smoothness of the error function and the ability of the optimization algorithms to cope with local minima. Visualize it this way: for any machine learning problem that needs to be solved, there are answers and better answers. Take visual classification. If the system (or you) gets shown an image of a coatimundi and a label that says coatimundi (heh, I’m running in New Mexico right now…), learning that image-label association involves adjusting weights assigned to different pixels in the presentation image down through multiple layers of the network that provide increasing abstractions about the features that define a coatimundi. And, importantly, that define a coatimundi versus all the other animals and non-animals.,

These weight choices define an error function that is the optimization target for the network as a whole, and this error function can have many local minima. That is, by enhancing the weights supporting a coati versus a dog or a raccoon, the algorithm inadvertently leans towards a non-optimal assignment for all of them by focusing instead on a balance between them that is predestined by the previous dog and raccoon classifications (or, in general, the order of presentation).… Read the rest