Sunday, December 31, 2006

** A Brief Tour of Human Consciousness by V.S. Ramachandran

An interesting book on your brain. Ramachandran's hypotheses on the evolutionary development of laugther and language are thought provoking and plausible. If you enjoy this subject, I would highly recommend "On Intelligence" by Jeff Hawkins.
(scroll down to see the post!)

What biological purpose does laughter serve? The common denominator of all jokes is a path of expectation that is diverted by an unexpected twist necessitating a complete reinterpretation of all the previous facts – the punch line. But clearly a reinterpretation alone is insufficient… It has be inconsequential, no real harm has been done. I would argue that laughter is nature’s way of signaling that it’s a false alarm. Why is this useful from an evolutionary standpoint? Laughter evolved to inform our kin who share our genes: don’t waste your precious resources on this situation; it’s a false alarm. P21-2

Vision evolved mainly to discover objects and to defeat camouflage… What you get inside the eyeball on the retina is just a mass of yellow line segments obscured by the leaves. But the visual system in the brain knows that these different yellow fragments being exactly the same yellow simply by chance is zero. They must below to one object. It links them together, decides it’s a lion (based on the shape), and sends a signal to the limbic system telling you to run. P50

A nude behind a diaphanous veil is more alluring than a playboy pinup. Why? After all the pinup is much richer in information and should excite more neurons… But if our brains evolved in highly camouflaged environments, and imagine if you are chasing your mate through dense fog, then you want every stage in the process – every partial glimpse of her – to be pleasing enough to prompt further visual search – so you don’t give up the search prematurely in frustration. The wiring of your visual centers to your emotional centers ensures that the very act of searching for the solution is pleasing. P51

A simple doodle of a nude can be more evocative than a color pinup. Similarly a cartoon like drawing of a bull in Lascaux is much more powerful than a photo of a bull. Hence the aphorism ‘Less is more’. But why should it be so? The answer to this paradox lies in another visual phenomenon: attention. There can’t be two overlapping patterns of neural activity simultaneously. Even though the human brain contains a 100B nerve cells, no two patterns may overlap. In other words, there is a bottleneck of attention. The main information about the sinuous, soft contours of a pinup are conveyed by her outline. Her skin tone, hair color, eyes, etc. are irrelevant to her figure as a nude. All this irrelevant information clutters the picture and distracts attention from where it needs to be directed. By omitting such irrelevant information, the artist is saving your brain a lot of trouble. P52

Why do humans bother creating and viewing art? There are at least 4 possibilities – none mutually exclusive. 1st, it is possible once laws of aesthetics have evolved (what makes a woman beautiful tends to forecast fertility and health) then they may be artificially hyperstimulated (think Venus of Willendorf). 2nd, artistic skill may be an index of skillful hand eye coordination and therefore an advertisement of good genes. This is a clever idea that I don’t find convincing… Why not use a much more straightforward index such as archery or javelin throwing? 3rd, people acquire art as a status symbol to advertise wealth. 4th, art may have evolved as a form of virtual reality stimulation. When you imagine something many of the same brain circuits are activated as when you really do something. This allows you practice scenarios without incurring the energy or risks of a real rehearsal. But there are obvious limits. Evolution has seen to it that our imagery isn’t perfect. If reality and imagination were the same in our brains, why would we ever pursue real food and mates when we can imagine a feast followed by an orgasm? For this reason, we may create real images (art) as props to rehearse real hunts or to teach children. P56

How did we evolve language and a shared lexicon? There’s a pre-existing, non-arbitrary translation between visual appearance and auditory representation. Admittedly this is small, but that is all that is required in evolution to get something started. Don’t believe it? Try this. Think of the words booba and kiki. And now think of a spiky shape and a bulbous shape. What shape goes with what word? 98% of respondents associate blob shape with booba and the spiky shape with kiki. This is also true for non-English speak Tamillians for whom the shapes bear no resemblance to the shapes of the letters B or K. But this is only part of the story. There is also a pre-existing cross activation between visual area and the muscles of vocalization. How do we know that? Say ‘teeny weeny’, ‘un peu’, ‘dimunitive’. Look at what your lips are doing: they are physically mimicking the visual appearance of what you are saying. Now say ‘enormous’, ‘large’, ‘huge’… There is also pre-existing cross activation between the hand area and mouth area, which are right next to each other in the brain. When people cut something with scissors they clench and unclench their jaws unconsciously, as if to echo the movements of the fingers. A system of non-verbal communication would have been important to our ancestors unable to engage in loud communication when hunting. Combine these 3 pre-existing cross activations; visual to auditory, visual to mouth, mouth to hand, and you get humankind’s first words. But how do we explain syntax? … The tree structure of syntax may have evolved from tool use. Early hominids were very good at tool use: step 1 take a flintstone and chip into a sharp edged cutting device; step 2 attach it to a handle; step 3 wield it as an axe for chopping. There’s a close operational analogy between this function and the embedding of noun clauses within longer sentences. So perhaps what was originally evolved for tool use is now exapted to be used in aspects of syntax. P78-80

In an emergency, the combination of shutting down your emotions (limbic system) while being hyper vigilant is useful. It is better to do nothing than to engage in some sort of erratic emotional (panic) behavior. But what if this state is triggered by a brain disease when there’s no emergency? A person who’s intensely alert will observe the world devoid of emotional meaning because their limbic system has been shutdown. There are only 2 possible ways to interpret this strange predicament; either the world isn’t real or I’m not real. We see precisely this in some epileptic seizures that affect this part of the brain. P93

If I imagine a clown in front of me, I don’t confuse it with reality because my brain has access to the internal command I gave to perform the imagination. I am expecting to visualize a fake clown, and that is what I see. It is not a hallucination. But if the expectation mechanism becomes faulty, then I’d be unable to tell the difference, and I could easily believe that that imagined clown is real. Similarly I could momentarily entertain the though that it would be nice to be Napoleon, but in a schizophrenic this thought becomes a full blown delusion because this circuit is damaged. P94

Quick schizophrenia test: Using your right index finger, tap repeatedly your left index finger, keeping your left finger steady and inactive. Notice how you feel the tapping mainly on the left finger, and very little on the right finger. That is because your brain has sent a command from the left hemisphere to the right hand saying move, alerting the sensory area of the brain to expect some touch. Your left hand, being perfectly steady, is surprised by the taps. A schizophrenic would the feel the sensations equally in both fingers since he’s unable to differentiate between internally generated actions and externally generated stimuli. P94

When courting a man, a blushing woman is saying ‘I can’t lie to you about an affair or cuckold you without my blush giving me away- I’m reliable.’ If this is correct, autistic children should not be able to blush. P107

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