Candide

How do you explain the psychological constancy of colour?

In his series of paintings of Rouen Cathedral, Claude Monet captured the dramatic changes in colour of the Western Façade throughout the course of the day, from the blue haze of early morning to the fiery orange at sunset. Monet was a genius because he saw the world differently to normal people; his paintings are striking because they capture something our visual system is hard-wired not to perceive. For the average human observer, the apparent colour of a surface remains constant in spite of the spectral composition of the illuminant changing. A red dress is red in sunlight, electric light and even in the neon blue lights of a nightclub – red is red, even when it isn’t! Two main types of explanations have been suggested to account for this phenomenon of Colour Constancy – global explanations involving the cerebral cortex downward (e.g. Land’s Retinex Theory) and local explanations involving just the lateral geniculate nucleus and retina (e.g. local adaptation). Recent experiments by Kraft and Brainard have shown that this is a false dichotomy – by progressively silencing different cues in the scene, they have shown that no one mechanism is responsible for colour constancy. Instead it is likely that the visual system extracts as much information as it can from the scene – both local and global – to maintain colour constancy.

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• 28 Dec 2012
• 3

What is life?

When the geneticist J.S.B. Haldane challenged himself to explain what life is, his initial response was despair:

“I am not going to answer this question. In fact, I doubt if it will ever be possible to give a full answer, because we know what it feels like to be alive, just as we know what redness, or pain, or effort are. So we cannot describe them in terms of anything else.”

Haldane reasoned that it was impossible to fully define life scientifically because humanity has an intuitive knowledge of what things to call living – we can only mimic and give some validity to what we already know to be true. But does Haldane not gift our intuition far too much explanatory power?

Before we discuss what life is, we must examine the origin and veracity of this apparently ironclad intuition. Our intuition, I will argue, is the root of two misleading ideas about life: Vitalism and Essentialism. I want to see whether they can be replaced by a gene-centred view of life – life as the expression of information encoded in the genome. Then I move on to Erwin Schrödinger’s idea that life is special because it appears to defy the universe’s descent into disorder. I will attempt to bring the two ideas together by equating orderliness with information. Finally, I discuss James Lovelock’s Gaia Theory, which posits a living earth, explaining it in terms of Richard Dawkins’ Extended Phenotype. I end, however, with some cautionary words demonstrating why defining life is one of science and philosophy’s most difficult tasks.

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• 3 Nov 2011
• 5

Had an interesting discussion with a friend today about ants and brains.

He says how can the charge on an ion travelling down a neuron constitute thinking?

I reply with the usual spiel about action potentials being like transistors switched on, possessing no meaning in themselves, but creating a higher order pattern that makes up thought.

However, on the bus it occurred to me that this analogy is just so dry and unintuitive to most people. Maybe a better analogy would be that of a worker ant scurrying down a tunnel in an ant test, bearing a morsel of food and secreting pheromones. Alone that ant is nothing, meaningless. But in the actions of every ant we see a colony - a super organism - emerge, where food is transported where its needed, and pheromones signal to other workers where they are needed.

The actions of an ant are inexplicable unless understood as one part of incredibly complex whole - the whole being the only thing intuitively understandable. In the same way, a voltage jump in a neuron is not thinking, the pattern of millions of voltage jumps is thinking. But this property ‘thinking’ is independent of the nature of the voltage jump, in the same way the social organization of an anthill is independent of (underivable from!) the nature of the individual ant.

So my new analogy. Neuron = Ant. Action potential = ant’s actions. Synapse = pheromones. 

And finally.

Brain = Anthill

• 31 Oct 2011
• 173

The God The Brain Made

At mass, when they chant the creed, I like to look around at everyone’s rapt faces, glaze-eyed, robotically saying the words, unthinking but proud. I find it scary, I just can’t bring myself to ‘believe’ or put ‘faith’ in things. I have a wholly materialistic view of life - I don’t even believe in love, if by love you mean some magical ineffable quantity. But I do know my germ-line has been adapted over millions of years to feel attraction, even devotion, towards other human beings with whom I might copulate - and that this feeling is what we call love, a feeling reducible to brain chemistry. I don’t find this depressing - the fact I know why I feel them doesn’t make my feelings any less real. By the same token, I know my germ line has been adapted to attribute a living cause to most phenomena, including all ‘creation,’ and that this is why I see the coat on the line as a person, and why people chant the creed every Sunday. But all the same, although an evolutionary penchant for belief in the supernatural exists, that does not make the object of belief real. In the same way that love isn’t some new force of nature, God isn’t a man in the sky - God, like love, is a part of human nature, which exists only inside our mind. God and love have a material existence only in the brain. But, I wonder, to paraphrase Albus Dumbledore, does that make them any less real?

“We believe in one God, the Father, the Almighty, maker of heaven and earth of all that is seen and unseen. We believe in one Lord, Jesus Christ, the only Son of God, eternally begotten of the Father, God from God, Light from Light, true God from true God, begotten, not made, one in Being with the Father. Through Him all things were made. For us men and for our salvation He came down from heaven; by the power of the Holy Spirit He was born of the Virgin Mary, and became man. For our sake He was crucified under Pontius Pilate; He suffered died, and was buried. On the third day He rose in fulfillment of the Scriptures; He ascended into heaven and is seated at the right hand of the Father. He will come again in glory to judge the living and the dead, and his kingdom will have no end. We believe in the Holy Spirit, the Lord, the giver of life, who proceeds from the Father and the Son. With the Father and the Son He is worshiped and glorified. He has spoken through the Prophets. We believe in one holy catholic and apostolic Church. We acknowledge one baptism for the forgiveness of sins. We look for the resurrection of the dead, and the life of the world to come. Amen.”

The creed shows that a belief in God certainly exists, and thus that God also certainly exists as some pattern of neural connections in the brain, but not, to the best of our knowledge, as some entity outside our brain. The brain embodies God. The language of the creed embodies the brain state which embodies God - in a sense then God exists in the creed. So God exists, yes, but only in the belief in him…

I want to be a neuroscientist. I am a materialist. The one thing I believe is that the human brain is the most complex and powerful piece of biology the human race has ever come across - powerful enough, indeed, to create God. 

• 1 Sep 2011
• 2