A View on the Nature of Consciousness

In the process of communicating with other bloggers that are interested in the future of humanity and philosophy of mind, some upcoming discussions have been planned on a number of related topics. The first topic is: the nature of consciousness and its relationship to the prospect of artificial intelligence. In preparation for the discussion, I’ve summarised my position on this topic here. I’ve spent some time reading and thinking about the nature of consciousness, so I believe that my position has some firm evidence and logical reasoning supporting it. If requested, I’ll follow up with post(s) and comment(s) providing more detailed descriptions of the steps of reasoning and evidence. As always, I’m open to considering compelling evidence and arguments that refute the points below.

The Nature of Consciousness

1. Consciousness can be defined as its ‘nature’. We seem to define consciousness by trying to describe our experience of it and how others show signs of consciousness or lack of consciousness. If we can successfully explain how consciousness occurs — its nature — we could then use that explanation as a definition. Nevertheless, for now we might use a broad dictionary definition of consciousness, such as “the awareness of internal (mental) and external (sensory) states”.

2. Consciousness is a spectrum. Something may be considered minimally consciousness if its only “aware” of external-sensory states. Higher consciousness includes awareness of internal-mental states, such as conscious thoughts and access to memories. Few animals, even insects, appear to be without “awareness” of memory (particularly spatial memory). As we examine animals of increasing intelligence we typically see a growing sets of perceptual and cognitive abilities — growing complexity in the range of awareness — though varying proficiencies at these abilities.

3. Biological consciousness is the result of physical processes in the brain. Perception and cognition are the result of the activity of localised, though not independent, functional groups of neurons. We can observe a gross relationship between brain structure and cognitive and perceptual abilities by studying structural brain differences animal species of various perceptual and cognitive abilities. With modern technology, and lesion studies, we can observe precise correlations between brain structures, and those cognitive and perceptual processes.

4. The brain is composed of causal structures. The collection of functional groups of neurons in the entire body (peripheral and central nervous system) are interdependent causal systems — at any moment neurons operate according to definable rules, effected by only the past and present states of themselves, their neighbours and surroundings.

5. Causal operation produces representation and meaning. Activity in groups of neurons have the power to abstractly represent information. Neural activity has “meaning” due to being the result of the chain of interactions that typically stretch back to some sensory interaction or memory. The meaning is most clear when neural activity represents external interactions with sensory neurons, e.g., a neuron in the primary visual cortex might encode for an edge of a certain orientation in a particular part of the visual field. There is also evidence for the existence of “grandmother cells”: neurons, typically in the temporal lobe of the neocortex, that activates almost exclusively in response to a very specific concept, such as “Angelina Jolie” (both a picture of the actress and her name).

6. Consciousness is an emergent phenomenon.  Consciousness is (emerges from) the interaction and manipulation of representations, which in biological organisms is performed by the structure of the complete nervous system and developed neural activity. Qualia are representations of primitive sensory interactions and responses. For example, the interaction of light hitting the photosensitive cells in the retina ends up represented as the activation of neurons in the visual cortex. It is potentially possible to have damage to the visual cortex and lose conscious awareness of light (though sometimes still be capable of blindsight). Physiological responses can result from chemicals and neural activity and represent emotions.

7. Consciousness would emerge from any functionally equivalent physical system. Any system that produces the interaction and manipulation of representations will, as a result, produce some form of consciousness. From a functional perspective, a perfect model of neurons, synapses and ambient conditions is not likely to be required to produce representations and interactions. Nevertheless, even if a perfect model of the brain was necessary (down to the atom), the brain and its processes, however complex, function within the physical laws (most likely even classical physics). The principle of universal computation would allow its simulation (given a powerful enough computer) and this simulation would fulfil the criteria above for being conscious.

8. Strong artificial intelligence is possible and would be conscious. Human-like artificial intelligence requires the development of human-equivalent interdependent modules for sensory interaction and perceptual and cognitive processing that manipulate representations. This is theoretically possible in software. The internal representations this artificial intelligence would possess, with processes for interaction and manipulation, would generate qualia and human-like consciousness.

Philosophical Labels

I’ve spent some time reading into various positions within the philosophy of mind, but I’m still not entirely sure where these views fit. I think there are close connections to:

a) Physicalism: I don’t believe there is anything other than that which is describable by physics. That doesn’t mean, however, that there aren’t things that have yet to be adequately described by physics. For example, I’m not aware of an adequate scientific description of the relationship between causation, representation and interpretation — which I think are possibly the most important elements in consciousness. Nevertheless, scientific progress should continue to expand our understanding of the universe.

b) Reductionism and Emergentism: I think things are the sum of their parts (and interactions), but that reducing them to the simplest components is rarely the best way to understand a system. It is, at times, possible to make very accurate, and relatively simple, mathematical models to describe the properties and functionality of complex systems. Finding the right level of description is important in trying to understand the nature of consciousness — finding adequate models of neuronal representations and interactions.

c) Functionalism: These views seem to be consistent with functionalism — consciousness is dependent on the function of the underlying structure of the nervous system. Anything that reproduces the function of a nervous system would also reproduce the emergent property of consciousness. For example, I think the ‘China brain’ would be conscious and experience qualia — it is no more absurd than the neurons in our brain being physically isolated cells that communicate to give rise to the experience of qualia.

Changing Views

I’m open to changing these views in light of sufficiently compelling arguments and evidence. I have incomplete knowledge, and probably some erroneous beliefs; however, I have spent long enough studying artificial intelligence, neuroscience and philosophy to have some confidence in this answer to “What is the nature of consciousness and its relationship to the prospect of artificial intelligence?”.

Please feel free to raise questions or arguments against anything in this post. I’m here to learn, and I will respond to any reasonable comments.

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I spy with my computer vision eye… Wally? Waldo?

Lately I’ve been devoting a bit of my attention to image processing and computer vision. It’s interesting to see so many varied processes applied to the problem over the last 50 or so years, especially when computer vision was once thought to be solvable in a single summer’s work. We humans perceive things with such apparent ease, it was probably thought that it would be a much simpler problem than playing chess. Now, after decades of focused attention, the attempts that appear most successful at image recognition of handwritten digits, street signs, toys, or even thousands of real-world images, are those that, in some way, model the networks of connections and processes of the brain.

You may have heard about the Google learning system that learned to recognise the faces of cats and people from YouTube videos. This is part of a revolution in artificial neural networks known as deep learning. Among deep learning architectures are ones that use many units that activate stochastically and clever learning rules (e.g., stochastic gradient descent and contrastive divergence). The networks can be trained to perform image classification to state-of-the-art levels of accuracy. Perhaps another interesting thing about these developments, a number of which have come from Geoffrey Hinton and his associates, is that some of them are “generative”. That is, while learning to classify images, these networks can be “turned around” or “unfolded” to create images, compress and cluster images, or perform image completion. This has obvious parallels to the human ability to imagine scenes, and the current understanding of the mammalian primary visual cortex that appears to essentially recreate images received at the retina.

A related type of artificial neural network that has had considerable success is the convolutional neural network. Convolution here is just a fancy term for sliding a small patch of network connections across the entire image to find the result at all locations. These networks also typically uses many layers of neurons, and has achieved similar success in image recognition. These convolutional networks may model known processes in the visual cortices, such as simple cells that detect edges of certain orientations. Outlines in images are combined into complex sets of features and classified. An earlier learning system, known as the neocognitron, used layers of simple cell-like filters without the convolution.

The process of applying the same edge-detection filter over the whole image is similar to the parallel processing that occurs in the brain. Though the thousands of neurons functioning simultaneously has an obvious practical difference to the sequential computation performed in the hardware of a computer; however, GPUs with many processor cores now allow parallel processing in machines. If rather than using direction selective simple cells to detect edges we use image features (such as a loop in a handwritten digit, or the dark circle representing the wheel of a vehicle), we might say the convolution process is similar to scanning an image with our eyes.

Even when we humans are searching for something hidden in a scene, such as our friend Wally (or Waldo), our attention typically centres on one thing at a time. Scanning large, detailed images for Wally often takes us a long time. A computer trained to find Wally in an image using a convolutional network could methodically scan the image a lot faster than us with current hardware. It mightn’t be hard to get a computer to beat us in this challenge for many Where’s Wally images with biologically-inspired image recognition systems (rather than more common, but brittle, image processing techniques).

Even though I think these advances are great, it seems there are things missing from what we are trying to do with these computer vision systems and how we’re trying to train them. We are still throwing information at these learning systems as the disembodied number-crunching machines they are. Though consider how our visual perception abilities allow us to recognise objects in images with little regard for scale, translation, shear, rotation or even colour and illumination; these things are major hurdles for computer vision systems, but for us, they just provide us more information about the scene. These are things we learn to do. Most of the focus of computer vision seems to be related to concept of the “what pathway”, rather than the “how pathway”, of two-streams hypothesis of vision processing in the brain. Maybe researchers could start looking at ways of making these deep networks take that next step. Though extracting information from a scene, such as locating sources of illumination or the motion of objects relative to the camera, might be hard to fit into the current trends of trying to perform unsupervised learning from enormous amounts of unlabelled data.

I think there may be significant advantages to treating the learning system as embodied, and make the real-world property of object permanence something the learning system can latch onto. It’s certainly something that can provide a great deal of leverage in our own learning about objects and how our interactions influence them. It is worth mentioning that machine learning practitioners already commonly create new numerous modified training images from their given set and see measurable improvements. This is similar to what happens when a person or animal is exposed to an object and given the chance to view it from multiple angles and under different lighting conditions. Having a series of contiguous view-points is likely to more easily allow parts of our brain to learn to compensate for different perspectives that scale, shear, rotate and translate the view of objects. It may even be important to learning to predict and recreate different perspectives in our imagination.

Consciousness’s abode: Subjugate the substrate

Philosophy of mind has some interesting implications for artificial intelligence, summed up by the question: can a machine ever be “conscious”? I’ve written about this in earlier posts, but recently I’ve come across an argument of which I hadn’t considered very deeply: that substrate matters. There are lots of ways to approach this issue, but if the mind and consciousness is a product of the brain, then surely the  neuroscience perspective is a good place to start.

Investigations show that the activity of different brain regions occurs predictably during different cognitive and perceptual activities. Also there are predictable deficits that occur in people when these parts of the brain are damaged. This suggests that a mind and consciousness are a product of the matter and energy that makes up the brain. If you can tell me how classical Cartesian dualism can account for that evidence, I’m all ears. 🙂

I will proceed under the assumption that there isn’t an immaterial soul that is the source of our consciousness and directs our actions. But if we’re working under the main premise of physicalism, we still have at least one interesting phenomena to explain–“qualia“. How does something abstract and seemingly immaterial as our meaningful conscious experiences arise from our physical brain? That question isn’t going to get answered in this post (but an attempt is going to emerge in this blog).

In terms of conscious machines, we’re still confronted with the question of whether a machine is capable of a similar sort of conscious experience that we biological organisms are. Does the hardware matter? I read and commented on a blog post on Rationally Speaking, after reading a description of the belief that the “substrate” is crucial for consciousness. The substrate argument goes that even though a simulation of a neuron might behave the same as a biological neuron, since it is just a simulation, it doesn’t interact with the physical world to produce the same effect. Ergo no consciousness. Tell me if I’ve set up a straw-man here.

The author didn’t like me suggesting that we should consider the possibility of the simulation being hooked up to a machine that allowed it to perform the same physical interactions as the biological neuron (or perform photosynthesis in the original example). We’re not allowed to “sneak in” the substrate I’m told. 🙂 I disagree, I think it is perfectly legitimate to have this interaction in our thought experiment. And isn’t that what computers already do when they play sound or show images or accept keyboard input? Computers simulate sound and emission of light and interact with the physical world. It’s restricted I admit, but as technology improves there is no reason to think that simulations couldn’t be connected to machines that allow them to interact with the world as their physical equivalent would.

Other comments by readers of that Rationally Speaking post mentioned interesting points: the China brain (or nation) thought experiment, and what David Chalmers calls the “principle of organisational invariance“. The question raised by the China brain and discussed by Chalmers is: if we create the same functional organisation of people as neurons in a human brain (i.e., people communicating as though they were the neurons with the same connections) would that system be conscious? If we accept that the system behaved in the exact same way as the brain, that neurons spiking is a sufficient level of detail to capture consciousness, and the the principle of organisational invariance, the China brain should probably be considered conscious. Most people probably find that unintuitive.

If we accept that the Chinese people simulating a human brain also create a consciousness, we have a difficult question to answer; some might even call it a “hard problem“. 🙂 If consciousness is not dependent on substrate, it seems that consciousness might really be something that is abstract and immaterial. Therefore, we might be forced to choose between considering consciousness an illusion, or letting abstract things exist under our definition physicalism. [Or look for alternative explanations and holes in the argument above. :)]

Rewards and values: Introduction

Reward functions are a fundamental part of reinforcement learning for machines. Based partly on Pavlovian, or classical conditioning, exemplified by the pairing of ringing a bell (conditioned stimulus) with the presentation of food (unconditioned stimulus) to a dog repeatedly, resulting in the ringing of the bell alone to cause the dog to salivate (conditioned response).

More recently, developments in reinforcement learning, particularly temporal difference learning, have been compared to the function of reward learning parts of the brain. Pathologies of these reward producing parts of the brain, particularly Parkinson’s disease and Huntington’s disease, show the importance of the reward neurotransmitter dopamine in brain functions for controlling movement and impulses, as well as seeking pleasure.

The purpose and function of these reward centres in the basal ganglia of the brain, could have important implications in way in which we apply reinforcement learning. Especially in autonomous agents and robots. An understanding of the purpose of rewards, and their impact on the development of values in machines and people, also has some interesting philosophical implications that will be discussed

This post introduces what may become a spiral of related posts on concepts of rewards and values covering:

Hopefully this narrowing of post topics results in giving me focus to write and some interesting discourse on the each of the themes of this blog. Suggestions and comments are welcome!