Adventures in Memory

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If you try to think about the last talk that you gave to a large audience, you might recall feeling a bit anxious standing in front of the audience. You might remember people looking at you and how the room looked like. This memory feels complete. Yet, you don’t recall the actual faces of the people in the room, or the details of the room, or the exact setup. This is the magic of memory. Memory is reconstructive.

This particular aspect of memory is one of the many aspects of memory addressed in the book from Hilde and Ylva Østby, “Adventures in Memory: the Science and Secrets of Remembering and Forgetting“. The title is well chosen. The book takes you into a journey about memory, explaining some facets of memory in a tone mixing popular science, journalism, and story telling. Originally written in danish, the cultural references in the book make you travel a bit in scandinavia. It was a refreshing change.

Beside the fact that mermoy is reconstructive, you will learn in the book for instance the difference bewteen semantic and episodic memory; how memory is triggered by places or music; that some people have weird perceptual experiences like synesthesia; techniques to learn random digits; the role of false memories in the judicial system; how remembering and dreaming trigger the same brain activity; what post traumatic disorder really is; and get a confirmation that forgetting things is normal.

I probably actually have already forgotten a lot of details of the book and the list in the paragraph above is far from exhaustive.

As a teenager I always wondered how come that some friends could recall and tell stories way better than me. It turns out I have now the explanation. Our memory isn’t a functional unit that’s identical in every individual. Everybody has a different memory that profoundly shapes who we are and how we experience the world. Mermoy isn’t only about storing facts, it’s also intimately tied to our perception and imagination.

Maybe memory has always fascinated me without me realising it: some of my favourite movies are Be Kind Rewind or Eternal Sunshine of the Spotless Mind. But funilly I had never read anything about how memory works. I’m glad I bumped on this book by serendipity.

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The Inevitability of Superintelligence

If we assume that the brain is a kind of computer, artificial intelligence is the process of reproducing its functioning. Based on this hypothesis, it’s easy to dismiss the possibibility of above-human intelligence by arguing that we can only program what we understand, which would means the intelligence in the machine is bounded by our own. But it’s also very easy to refute this limitation by arguing that we encode learning processes in the machine. These learning processes would be working at a scale and speed that we can’t match. The machine will beat us.

This later argument definitively seems to hold if we look at recent achievements in deep learning. Computer achieve some tasks that very much ressemble some form of intelligence. Looking more carefully, it’s however questionable whether we should speak of intelligence or simply knowledge. Techniques like deep learning enable computers to learn facts based on large amounts of data. These facts might be very sophisticated, ranging from recoloring images correctly to impersonating the artistic style of a painters. But the computer isn’t intelligent because no reasoning really happen.

This leads actually to an interesting question about intelligence. How much of intelligence is simply about predicting things based on experiences? If an object fall, you predict its position in the future to catch it, based on other experiences with falling objects. If someone asks you a “what’s up?”, you can predict that they expect to learn about what’s going on.  With GPT-3, which works according to this principles, you can almost have a conversation. I say almost, because we also see the limit the approach. There are some classes of question that don’t work, like basic arithmetic.

Current artificial intelligence is able to learn, either by analysing large quantities of data (deep learning) or simulating an environment and learning what works and what doesn’t (reinforcement learning). But we’re still far from sentient, thinking machines.

If we assume that our brain is some kind of computer performing a computation, there’s however nothing that prevent us from replicating it. With this line of thought, it’s only a matter of time until we “crack” the nature the intelligence and will find the right way to express this computation. When this breakthrough will happen is unknown – maybe in a decade, maye much later – but there’s nothing that make it impossible. With sufficient perserverence, this breakthrough is inevitable.

Speaking in terms of computation and data, a system becoming smarter can happen in two ways. The first one, is what we have now. Systems that learn over time through the accumulation of data. The computation remains the same though. A deep learning network is programmed once (by human!) and than trained on large quantities of data to adjust its paramter. But maybe a second class of systems exists: system that self-improve by changing their computation. Systems able to inspect and change themselves do exist and are called reflective systems. In such a system, data can be turned in computation and computation into data. The system can thus modify itself.

Some people believe that with artificial intelligence, we risk beeing outsmarted by a “explosition” of intelligence. Systems of the first class learn within the bounds of the computation that defines them – however complex this computation is. The possibility of an explosion is limited. With systems of the second classes, we’re free to speculate, including the possibility of an explosion of intelligence. Such a system could outsmart us and lead to superintelligence.

If we assume that our brain is a computation: is it self-improving or not? Children acquire novel cognitive capabilities over time, which at least give the illusion of self-improvement. But maybe these learnings are only very complex form of data accumulation. Also, the boundary between reflective and non-reflective systems is not black and white. A fully reflective system can change any aspects of its computation, whereas a non-reflective system processes input data according to fixed rules that never changes. A system that is able to infer and defines some rules for itself would fall in between both categories: the rules can change, but to an extent that is limited to some aspect of the computation. The adaptive nature of neural networks could, in some way, be seen as a limited form of rule changing: the rules are fixed, but the “weight” given to them change over time due to feedback loops.

Learning requires data provided by an environment. We’re able to learn only because we interact with the world and other people. If we were to replicate the computation in our brain and the learning process that takes place, we would also need to simulate the environement. The computational complexity of all this is probably enourmous. Maybe we can replicate the computation in our brain, but not the environment, or only limited forms of it. In which case, it’s hard to tell what kind of intelligence could be achieved.

Depending on the computation and environment that we simulate, the intelligence won’t resemble human intelligence much. The algorithm of AlphaGo learns in an enviornment that only consists of the Go rules. We can not even image what this world would be like. Assuming that the artificial intelligence is human-like misjudges the nature of human intelligence. Intelligence is not one quantity that we can weight based on clear criterium. Intelligence has many facets and is contextual.

For some facets, like arithmetics, machines are for sure already superintelligent.

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The Brain and Probabilities

The brain is a wonderful machine with an impressive computing power. We can make sense of complex information effortlessly and almost instantly. But it has one big flaw: it does not understand probabilities.

When presented with information, the brain tries to explain it by building a coherent story out of it. To do so quickly, it relies on some shortcuts, which largely ignore probabilities. So the story you get isn’t necessary the most probable, but instead the cheapest it could construct, as long as the story remains plausible.

One of the shortcuts is to trade availability of information for probability (availability heuristic): the information you can recall quickly is deemed more probable than other information. As a result, the probability of sensational events inflates while the probability of mundane events shrinks.

Another of the shortcuts is to only consider what is visible and extrapolate from there (all there is is what you see): only the visible information is considered, without even considering that something could be missing from the picture. Somebody looking nice will be considered a nice person, unless additional negative information about him is given.

The brain tries so hard to build a story that it will see patterns even in random data. It will infer causality very quickly, and with very little. As Kahneman puts it, the brain is “a machine for jumping to conclusion”.

It important to remember the dinstinction between plausible and probablewhen it comes to judgment, because we’re taking decisions all day long.

You hear a project was using a new methodology and was very successful with it so you want to use it as well? Beware the survivorship bias. You don’t know how many projects used the methodology and failed…

You think the biggest risk in your project is a distributed attack from China? Beware the availability heuristic. Your biggest risk might be to not have proper input validation…

You see bug reports for your teams and start detecting a pattern? Beware the law of small number. Your sample size might be too small…

Our brain is hardwired to tell us stories. So it’s very hard to improve on our handling of probabilities. Often, we’re simply not aware that probabilities are at play. And even when we are, it’s really hard to change our instinct in some cases: if you flip 9 times a coin and  got 9 times head, the probability to get tail on the 10th flip is higher, right? Well, actually not. But it’s hard to not feel otherwise.

So, the best remedy is to default to a healthy skepticism and accept that the outcome of many situations in life is simply the result of chance. It might sound like fatalism but it isn’t at all. Your actions will influence the outcome of many situations, but you don’t know how. Don’t buy the first plausible explanation your brain tries to sell you, it’s probably not the right one.

References 

Lateral Thinking

Lateral thinking is a term coined by Edward De Bono to characterize the generation of alternative ideas, as opposed to vertical thinking, which generates ideas based on logic and stepwise refinements. Another way to explain lateral thinking in a much common way is “thinking out of the box.”

Often finding the best solution to a problem requires a creative move to go away from the existing solution and start with a new angle. This is were lateral thinking can help.

As a reminder of the power of lateral thinking, let us take an egg and a spoon. You are doing a brunch. How do you provide assistance to help cut the egg?

With vertical thinking you might come up with this solution:


With lateral thinking, maybe with this one:


I was absolutely amazed the first time I saw this device in action. The cut is perfect. Also, I would probably never have come to this solution, no matter how long I stared at my egg.

Each time I discuss a design issue I remember my last brunch and try to take some distance with the situation to go back to the root of the problem to solve and ask: could we do this completely differently?

Sometimes the best way to cut an egg is to not cut it actually.

The Zen of Oscar

Writing a good research paper or thesis is hard. It can be very intimidating to figure out the scope of the work needed to be done. Thanks to Oscar, I have been empowered with three adjectives to  think about problems of scope. These adjectives were: breadth, depth and completeness.

Breadth and Depth

At the early stage of my thesis, I prepared a list of action items that I proposed to address for my research. I went to see Oscar for a confirmation that addressing these points would lead to a good thesis. I described him the list of action items and asked “Oscar, if I realize all this, will this make a good thesis?”. He look at me and said “For a good thesis, you must cover a topic with sufficient breadth and depth“. I came back to my office, confused and worried.

What I had failed to understand is that a thesis needs a frame. A frame has a breadth, and depth. The breadth characterizes the perspectives on the idea, and the depth the level of details. Say, your thesis is about dynamic updates. Technical feasibility and user adoption are two perspectives that belong to the breadth dimension. Implementation and formalization are different levels of details that belong to the depth dimension.

Different pieces of work have different ratios of breadth and depth. A position paper might have lots of breadth, but little depth. A paper proposing an optimization of an algorithm has little breadth, but lots of depth. For a thesis, you need a good ratio of both.

Completeness

Later on, I was once invited to prepare an extended version of a conference paper for a journal. I prepared a draft of the changes and went to see Oscar. I asked “Oscar, are my changes enough for an extended journal paper?”. He looked at me and said “For a journal paper, you must do what is necessary for your research to be complete“. I came back to my office, confused and worried.

What I had failed to understand is that maturity of research is not defined by how much has been done in terms of effort, but by the actual amount of speculation left. Research is an incremental process, and a piece of research is complete when all that was needed to support the claim (results or analysis) has been provided. Let’s imagine that you have an implementation of a dynamic update algorithm that you claim is efficient. You must show efficiency in speed and memory use for the research to be complete.

Thinking in terms of breadth, depth and completeness has become a simple technique in my toolkit of planning methods.

Mind Blown

There’s lots of things to learn and know. Some are funny trivialities, some are joyful discoveries, some are intriguing theories, some are insightful lessons, … and some are mind-blowing revelations.

Here’s my top 10. Some of them still blow my mind!

Things are only impossible until they’re not. — Jean-Luc Picard

Have fun!

  1. Public-key cryptography
  2. Lamport’s bakery algorithm for mutual exclusion
  3. Meta-circular evaluation and homoiconicity
  4. Storing state with flip-flop
  5. 0.999… = 1
  6. Non-Euclidean Geometry
  7. Imaginary numbers
  8. The necessity of axiom of choice
  9. Fixed-point combinator
  10. Escape velocity